I just wanted to share my experience in case it might help someone interested in AI cartridges.

I have had a .338-06 AI for about a year. It is my first foray into the non-factory chambered cartridges. I also want to note that, though I had help from various internet forums including this one, I know no one personally with Ackley Improved experience. There were some people who were very right in their advice and some who were very wrong. Also there are more than two ways to do things.

To form the cases I necked up new Nosler .30-06 brass to .338 in one step in my .338-06 AI full length sizer die. Then I used 200 gr Accubonds and 225 gr Interbonds with published middle of the road loads of H380 for a regular .338-06. Bullets were seated 0.020 inches off the lands. When I fireformed, all cases had beautiful shoulders but some would have flattened primers, some would have primers slightly pushed out, and a few formed cases would be normal. Primers were much easier to seat in most of the cases, though I wouldn't call the primer pockets loose.

Here is what I learned that may account for my primer difficulties:

1. When necking up the original brass I must have run some of the cases all the way into the full length die, thus setting the shoulder back and creating a head space problem. I think this accounts for the slightly pushed out primers.

2. Even though the H380 load was from published data, I believe it is much too fast a powder to be used in this case. I think I created a high pressure situation, which accounts for the flattened primers. For those wondering why I used H380, my .22-250 doesn't like it so I had it to burn.

I have since fireformed new cases(necked up with the necksizing die) with the same bullets plus 200gr Speers and IMR 4350. I had no primer issues and the cases formed nicely.

Here as some other things I have learned in my Ackley Improved Adventure:

1. Even though you can go directly from 30 caliber to 338 caliber, I think you will get more consistent case necks if you take an intermediate step of necking up to 8mm. I haven't done this yet but I have some cases with crooked necks due to the uneven pressure from the expander ball.

2. You really should have a chronograph when finding max loads for you wildcat/improved cartridge. There is no way you can go by the rule that AIing you cartridge adds x%(I have heard between 3 and 6% for the .338-06). You can go from a normal fired case to a blown primer in less than a grain of powder. I think individual guns vary too much and brass varies too much between manufacturers and lots. Start a grain or two below max with published data if you can find it and work up in 0.5 grain increments or even 0.3 gr once you get towards the top. I load one round per powder weight up to my set limit. I don't have a chronograph yet, so after one blown primer I am limiting myself to 1.5 gr over published max in the unimproved cartridge until I save up. That works out to about a 2% increase for me.

3. Unless you have a good amount of first hand experience with someone, you never really know who's advice to believe. There are many experienced people who are "right" about alot of things. That doesn't mean they are "right" about your gun/cartridge. By all means, ask questions and learn from others but take everything with a grain of salt. Most importantly, try get to know someone with experience in what you are doing(like I didn't). If you don't have that opportunity(like me), these forums are great. Just be smart.

I will try to post any other info I find interesting as I stumble along. Hopefully this is useful to someone. Thank you all for previous and future help.

Dylan

Dylan, AIs are no different from any other cartridge in one respect, pressure. Start low and work up. Your rifle and chambering are different from the next guys and there are no shortcuts or hard and fast max charges.

I know that you discovered this, the hard way, but hopefully your post will help others down the right path.

I've been loading the .338-06 for over twenty years, perhaps I can help. First, H380 is definitely NOT too fast for the .338-06. In fact it is on the slow side for most bullets. It is not a powder that performs well in moderate loads, at least not in my experience. I get best performance with 200-grain bullets using IMR4064 and IMR4320 - both somewhat faster than H380.

You are getting some flattened primers not from excessive chamber pressure, but from a combination of excess headspace and inconsistent pressures due to a small charge of a slow powder. Flattened primers are a poor indicator of pressures anyway.

The excess headspace may not be your fault. I corresponded with P.O. years ago and he told me that one of the biggest problems with "improved" cartridges was improper chambering. A correct chamber leaves a crush fit between the '06 case shoulder and the chamber, this ensuring tight headspace. When rechambering an existing chamber to an IMP cartridge, the barrel must be set back a turn to obrtain the crush fit. Your gunsmith may have run the finishing reamer in too far, creating your problem. Be careful when resizing your cases - back out your FL die so you don't set the shoulder back and things should be fine.

I open up the .30-06 case mouths in a single pass through the Redding FL die. I have tried it in two steps but still had uneven case mouths after I was done - simple to cure with a case trimming.


.

"Start low and work up" and if in doubt stop low. Thats my motto.

TX Nimrod- Thanks for your insite and for correcting me on H380. I wasn't aware it was finicky at moderate loads that explains some of my inconsistent primer signs.

I was concerned about the possibility of excessive headspace from the very first time I saw the protuding/flattened primers. This barrel is a new barrel and not a rechambered barrel. It is definitely possible my smith could have run the reamer in too far when chambering.

I haven't had the headspace checked by a different smith, though it is probably a good idea. I didn't pursue that route because I read of accidentally setting the shoulder back when necking up with a full length die and decided to try that first. My current brass to be fireformed was carefully necked up with the neck sizer die to disturb the shoulder as little as possible. I have had zero problems out of 50 firings from this brass. I my first batch around 30 of 50 rounds had either flattened or protruding primers. I would be interested to hear yours or anyone's thoughts on this.

I have read of the "crush fit" you are supposed to feel when chambering a standard cartridge in an Ackley chamber. I know that my first loads to fireform did not have a crush and that my current loads to fireform have a crush, though I am unsure how much of a crush there should be. Some day I will try factory .338-06 ammo to see how that feels.

I have not used the full length die to resize any brass. I only plan to use the neck sizer and hopefully I won't need to use the full length die because of the reduced case stretch. Looks like I will have to buy a good case trimmer to even out my case necks. Right now I have modified a Lee trimmer to trim 0.040" shorter than SAAMI spec .338-06 brass.

quote:

2. You really should have a chronograph when finding max loads for you wildcat/improved cartridge. There is no way you can go by the rule that AIing you cartridge adds x%(I have heard between 3 and 6% for the .338-06).

% of what? Only true % gain in capacity is measured in the same case before and after.
I will agree with you 100% that each rifle , chamber, case is one and only one data point. Comparing gains between two rifles one std and on AI tells you very little.

I also agree I have seen in AI case a half gr go from no pressure sign to blown primers. The pressure was there before the .5 gr it just didn't show.

Rules of thumb are just that rules of thumb. Take any and all with a gr of salt.

I've tested several calibers in std up through AI and my old improved cases some in the same barrel. So I have a lot more experience than one data point. Saying that I have expectations like 1% velocity for 4% capacity when I build a AI or my PDKs. But I wouldn't bet any serious $$ on any of them. If you don't arrive at a powder that allows you to take advantage of the extra capacity all you will do is burn more powder for the same velocity.

A proper AI should require a crush fit on a std case. Enough that you feel resistance as you close the bolt. Like a case needing the shoulder set back. Many home smiths as well as full time error by just running an AI in a std chamber. You can get by this way but that doesn't make it right. Set the die up for sizing after forming to not set the shoulder back or just touch the shoulder.

I've also found that a lot of the reduced triming comes from the AI case be shorter after forming from shoulder stretch.

quote:

Originally posted by dlutter:
...You really should have a chronograph when finding max loads for you wildcat/improved cartridge. ...

Hey Dylan, I disagree with that concept. There is no Chronograph (nor any Haphazard SGS) that will tell you spit about Pressure.

The only way to work with a Wildcat and know what is happening with the Pressure is the always reliable, never fail, inexpensive, time proven, repeatable - Case Head Expansion. Anything else is full-of-beans.

Best of luck to you.

Hello Dylan, as to case forming. Neck down Whelen brass to a crush fit or seat the bullets into the lands. You need to hold the case back against the bolt. I've had a bunch of wildcats, please feel free to PM if you have some questions. For the record I now own no wildcats.

When shooting a factory caes in a AI chamber the formed case is shorter.I think the crush fit is somewhere in the .020 +- range,I have a book somewhere that says to neck up past what you want then partal neck size to keep it snug in the chamber.

quote:

Originally posted by ramrod340:
[QUOTE]2. You really should have a chronograph when finding max loads for you wildcat/improved cartridge. There is no way you can go by the rule that AIing you cartridge adds x%(I have heard between 3 and 6% for the .338-06).

[QUOTE]% of what? Only true % gain in capacity is measured in the same case before and after.
I will agree with you 100% that each rifle , chamber, case is one and only one data point. Comparing gains between two rifles one std and on AI tells you very little. [QUOTE]

Sorry I should have been more clear. I have read several places were people talk that improving the .338-06 case increases case capacity "x"%. In this case I have heard between 3 and 6%.

Here is an example: A max load of RL 15 using a 210 gr Partition in a standard .338-06 is 53.5 gr. Your friend Bubba told you that Ackley Improving adds 5% to the case capacity of the standard. My thought is that you should not load up 56 gr of RL 15 and expect it to be safe. I have found, by working up slowly, my rifle/brass combo gives between 3 and 4% increase in max load depending on the powder. What one needs to do is work up on 0.5 gr or smaller increments watching pressure signs, velocity, and as Hot Core pointed out case head expansion.

quote:

Originally posted by Hot Core:

quote:

Originally posted by dlutter:
...You really should have a chronograph when finding max loads for you wildcat/improved cartridge. ...

Hey Dylan, I disagree with that concept. There is no Chronograph (nor any Haphazard SGS) that will tell you spit about Pressure.

The only way to work with a Wildcat and know what is happening with the Pressure is the always reliable, never fail, inexpensive, time proven, repeatable - Case Head Expansion. Anything else is full-of-beans.

Best of luck to you.

You are right, Case Head Expansion is the silver standard (gold standard being a pressure barrel). I still feel a chronograph is a necessity as it is one more thing to tip you off you are getting too hot.

MTM-Thanks for the invite on the PM. I will keep it in mind. I have had others tell me of necking down whelen brass. However, I already have 1000 new Nosler .30-06 brass that I bought on clearance.

Sorry I am going a little overboard posting tonight. Just wanted to say that I didn't start the thread to toot my own horn and act like I know it all(even though it may sound like it to some). I just wanted to share my experiences and get some discussions going so the next guy who has the same questions I had might be able to benefit from my experience.

You didn't come off (to me) as being a know-it-all, just a fellow wildcatting reloader passing on some information. With as little data as is available with many of these, first-hand reporting is appreciated.

Check back on this post in a few months andyou will see how many people typed 338-06 AI into a search.

In my 244 AI,I need to neck new cases up to 257,then neck down to 243 with the die set out a small amount.I then try to chamber the empty case.I then turn the die in a 1/8 turn at a time ,until the bolt will just close,but does so hard.Then the case is a crush fit.It leaves a "double shoulder" until fired.
I find I need a pretty stout load to properly form my 45degree shoulder, minimum taper case,usually about what is recommended as a max load for the standard 6mm case.Lesser loads leave a rounded ,weatherby radius shoulder - looking case.

One thing that has not been pointed out here about the AI chambers is the fact that when you fireform the cases, they reduce most of the taper from the parent cases. This will reduce the normal signs seen in standard case, as the straighter walls of the improved case will grip the sides of the chamber tighter, almost. if not, holding he case in place. This was proven by PO himself with several different test.

About the only true way to watch for pressures is measure case heads or with strain gauges mounted to the barrel.

You are correct in your thoughts about one rifle being different from another and the variables involved. Depending on the bore, and grove, the smoothness, the twist, several things can add up really quickly to a dangerous situation.

At this time I own three different calibers which have been AI'ed. In none of them is there a crush fit when closing the bolt, on a factory case. These cases fit just like they would in a standard chamber and headspace off the center line or datum line on the shoulder of the parent case. I have never seated a bullet into the lands to get a proper fit and you should not have to. The whole concept behind Ackley's design was to allow the standard original factory cases to be fired in the improved chamber to form the improved cases, with no other issues.

quote:

At this time I own three different calibers which have been AI'ed. In none of them is there a crush fit when closing the bolt, on a factory case. These cases fit just like they would in a standard chamber and headspace off the center line or datum line on the shoulder of the parent case. I have never seated a bullet into the lands to get a proper fit and you should not have to. The whole concept behind Ackley's design was to allow the standard original factory cases to be fired in the improved chamber to form the improved cases, with no other issues

I'll just have to disagree. I have no doubt you have three AI rifles that you can't feel the bolt close on factory ammo. There are plenty done that way. Just doesn't make it the way it was intended to be.

The distance from the base to the shoulder neck junction is .025-.03" shorter on an AI than a factory case. Which will end up giving you a crush fit. Sure you can fire a std in an AI that was the plan but if the AI chamber is done correctly a STD case will be tight.

In a MKX action I can take a 280 case and fire it in my 280PDK my shoulder is forward like a gibbs. It will fire and form because the extractor provides a headspace. Sure doesn't make it right are smart since the case is now VERY thin in the web.

Like I said many AI chambers are simply cut into a std chamber without set back. Headspces is long then on a std case. More than likely it will fire without the case separating. But it was not his design.

Well I have to agree to disagree. The chambers in my rifles have been checked by a friend of mine who was taught Ackley's procedure by PO himself at Trinity, CO. I highly doubt that he would teach the wrong way to chamber something which carried his name, and therefore I highly doubt that my chambers are wrong as they check out exactly as described in his writings. So you can believe what you want to about how it is supposed to be done, and whatever your friends tell you. I will go with the fellow and his diploma who was there and knows first hand how it should be.

Excerpt taken from "Handbook for shooters and Reloaders" by PO Ackley, pg 50 & 51,

ADDITIONAL COMMENTS ON HEADSPACE AND CARTRIDGE DESIGN

As described previously, the headspace of rimless cartridges is normally measured from the face of a locked bolt to some point on the shoulder called the datum line, and this datum line on the 30-06 and some others is the point which measures exactly .375 in diameter. The old method, however, was to measure the headspace from the face of a fully locked bolt to the top of the shoulder or the sharp corner at the junction of the body where the slant of the shoulder begins. The 30-06 is the only cartridge measured by the old method. The length of the 30-06 case from the face of the bolt or the cartridge head to the point of the shoulder is 1.94”, and the headspace is kept within limits of 1.94” and 1.946”. It must be kept in mind that that particular measurement which is not common to any other cartridge at the present time s from the head to the top of the shoulder. While on the .257 for example, the headspace is measured to the datum line which for the .257 is also .375” and the measurement from the face of the fully locked bolt to the datum line or the point measuring .375” in diameter on it’s shoulder is 1.7937”. This measurement is considered to be the minimum headspace measurement permissible. The maximum headspace permissible would be .005” to .006” in excess of this minimum measurement. Measuring the headspace of a 30-06 by the same method, namely from the face of the bolt to the datum line which is the .375” point on the shoulder, the actual the actual measurement for the minimum length of the chamber is 2.0479” in contrast to the figure commonly used of .940”. When considering improved cartridges and the chambering of the same it must be pointed out that the headspace must be considerably less that what we think of as minimum. For example, when chambering for the 30-06 we normally use a 1.940” gauge and get the bolt so that it will easily close with only a slight “feel” or close without any “feel” at all, but at same time will absolutely refuse to close on a 1.946” gauge which means the headspace of the chamber comes within limits and somewhere between these two figures. Therefore the 1.946” gauge becomes our no go gauge, since the bolt refuses to close at all on this maximum gauge. For the improved cartridge it is necessary to use the 1.940” gauge, as the no go gauge, and our go gauge must be approximately .004 shorter. Therefore our go gauge will become 1.936” When considering the .257 as a further example the standard minimum headspace for this cartridge is 1.794” with a maximum headspace or no go gauge measuring in the neighborhood of 1.800” or if the bolt will close on the 1.8” gauge the chamber is considered to have maximum headspace and should be corrected. The improved chamber will then require a gauge of 1.790” as the go gauge and the standard gauge of 1.794” will become the no go gauge. It must be remembered that all of this applies to rimless cartridges only and must be closely observed. The reason for all this is the fact that when headspacing for improved cartridges the practice will be to fire factory ammunition in the improved chamber and thus form the cases in that manner, a process which is known as fireforming. Since factory cartridges will be fired in a chamber radically different from the standard chamber which is relatively like the cartridge itself the only point of contact is going to be exactly at the junction of the neck and shoulder.

By observing this illustration it will be noted that the point of contact is necessarily only at this point. Once the cartridge has been fired the whole case will then take the form of the improved chamber, and shown as No 3 in the illustration, and from then on the whole thing can be considered as the standard cartridge is going to appear as shown in the illustration No 4 when it is fully chambered. The reason that the headspace must be somewhat less than popularly considered as minimum is that there is sometimes considerable variation in the length of individual cartridges when measured from the head to the junction of the neck and shoulder. When cartridges are inserted in chamber having relatively the same shoulder angle they are bound to contact at some point on the shoulder, but this is impossible when the factory cartridge is used in an improved chamber. Therefore extreme caution must be exercised to ensure an intimate contact at the only point possible. If this precaution is not observed and a standard factory cartridge is fired in an improved chamber which is slightly over the recommended minimum there is a good chance that the cartridge case will separate near the solid head when the charge explodes. This can easily result in a dangerous condition which can completely wreck the action to say nothing of the possible injury of the shooter.

quote:

Originally posted by dlutter:
You are right, Case Head Expansion is the silver standard (gold standard being a pressure barrel). ...

Hey DLutter, The problem with ANY Haphazard SGS used at home is they can not be Calibrated, and you must use Guessed-At Dimensions, unless you have access to a $$$HIGH$$$ CMM with a l-o-n-g Probe. Therefore all the info(certainly not Data) is pure speculation.

quote:

I still feel a chronograph is a necessity as it is one more thing to tip you off you are getting too hot.

You are certainly not alone with that belief. I'll "guess" 90% of all Chronographs that have ever been sold were because of that misconception. The only thing a Chronograph can tell a person is the "Velocity" of a specific set of components in one specific barrel. Change barrels to one made by the exact same process to the exact same dimentions and it is easy to see 100-300fps variation.

If a person actually has shot enough rifles chambered for the same Cartridge with the same barrel length, it is easy to recognize that is reality. Why it is so though, has always remained a mystery with all kinds of wild speculation as to the cause(s).

Due to that unknown variation, how would you know when a Load is too Hot with a Chronograph?

Not arguing with you, just trying to point out the obvious. I see a lot of money totally wasted on this Board by people buying Chronographs who actually think they will somehow be able to know what a "Pressure" happens to be by looking at a Velocity. It just does not work that way, regardless of what the fool Gun Rag scribes and Manufacturers may have said.

Anyway, best of luck with the rifle.

quote:

Originally posted by ramrod340:

quote:

At this time I own three different calibers which have been AI'ed. In none of them is there a crush fit when closing the bolt, on a factory case. These cases fit just like they would in a standard chamber and headspace off the center line or datum line on the shoulder of the parent case. I have never seated a bullet into the lands to get a proper fit and you should not have to. The whole concept behind Ackley's design was to allow the standard original factory cases to be fired in the improved chamber to form the improved cases, with no other issues

I'll just have to disagree. I have no doubt you have three AI rifles that you can't feel the bolt close on factory ammo. There are plenty done that way. Just doesn't make it the way it was intended to be.

The distance from the base to the shoulder neck junction is .025-.03" shorter on an AI than a factory case. Which will end up giving you a crush fit. Sure you can fire a std in an AI that was the plan but if the AI chamber is done correctly a STD case will be tight.

In a MKX action I can take a 280 case and fire it in my 280PDK my shoulder is forward like a gibbs. It will fire and form because the extractor provides a headspace. Sure doesn't make it right are smart since the case is now VERY thin in the web.

Like I said many AI chambers are simply cut into a std chamber without set back. Headspces is long then on a std case. More than likely it will fire without the case separating. But it was not his design.

Ramrod is correct here......a proper fit of a factory round in an "AI" chamber is a slight crush fit.

quote:

Well I have to agree to disagree

That's fine with me. As I read your first post stating that you feel no resistance when chambering a factory rd I ASSUMED your chambers were cut the way many are. Simply running an AI reamer into a factory chamber far enough to clean it up. If that is not the case then I was wrong in that assumption.

Your last post states exactly what I said earlier (thanks for providing it) a proper AI chamber is cut shorter than a factory. On a factory chambered barrel it must be set back to allow proper headspacing. Many hobbiest and even smiths don't take this step.

The instructions you posted states that an improved chamber has the headspace shortened so that a normal STD go guage becomes the no go. So if your chamber is cut shorter than a std chamber as the write up says and as I stated above and you can not feel a crush or a slight resistance as you chamber a std case I'll take your word for it. I've had over 30AIs over the last 35+ years with chambers cut shorter than STD as your write up discribes. I've never had one that I couldn't feel some resistance when I chambered a factory case.

As to what "my friends" told me since he worked with PO for several years I'll trust how he set up and taught me to set up my AIs.

dlutter and all,

I apologize for turning your post into what is has become. All I was pointing out were a couple of facts, but folks cannot even take the actual text from he man himself as fact so there ya have it.



THe above was posted earlier. After being in contact with the fellow I referred to in my post I do stand corrected by both Vapodog, and Ramrod340. We were all thinking along the same lines, only I was pointing to what I thought was correct information. It has been pointed out to me that they were both correct in their statements and I wasn't.

Again sorry to have hijacked your post.

I'm truly sorry you feel you need to take this tread this direction. As I stated I had assume from your first comment that your chambers were done incorrectly. As I stated if they were done like your second post then they are done correctly and my assumption was WRONG.

I stated in my first post that the AI chamber is shorter than the STD. Your instructions also state that. The std go guage becomes the AI no go.

I was taught that the NO GO meant this definition:
The “NO GO” gauge - is used to make sure a firearm does not have excessive headspace. The bolt should NOT fully close on the “NO GO” gauge, if the bolt cannot be closed on the “NO GO” gauge then you know your rifle does not have headspace that is excessive. The “NO GO” gauge can be thought of as a maximum headspace gauge and should not be able to fit in the rifles chamber with the bolt fully closed. If the bolt DOES close on the “NO GO” gauge, it does not necessarily mean that the rifle is unsafe; it does however show that a further check with the “FIELD” gauge would be necessary to determine if it is safe to shoot. POs instruction mentions that the bolt shouldn't close on a no go guage.

You are correct the PO instructions above do not mention the word crush or even resistance. However if the chamber is set up so that the no-go will not chamber in my experience and most others you will feel resistance as you close the bolt on a factory case. TxNimrod stated above he had been told that by PO himself. No way does anyone stating a crush fit mean that a factory case will not chamber. POs design was just that insure that the chamber would hold the std case without excess headspace so that it could be fireformed.

We AGREE on the proper setup of the chamber. As I stated if you feel no resistance I'll take your word for it. I've ALWAYS felt it and Vapodog simply agreed with me. Resistance and it's amount is hard to discribe I've never mesured it as to x number of #s increase in bolt pressure. I simply feel the case as being tight. Since many have felt resistance because they needed to bump their shoulder back it is easy to compare it to that. When I and most state a shoulder needs to be bumped back it is simply getting tight in the chamber but it will still chamber usually with a little extra pressure. Is one 2# the other 4# of resistance I have no clue.

It has nothing at all to do with number of posts. As I've stated we agree on the chamber if your agruement is that the PO instructions above do not mention crush I'll agree with you. I will also take your word for it that your chambers are set up per the instructions and you feel nothing different when you chamber a factory rd. I simply feel resistance or I and many call a crush fit. I'm not going to get hung up over what the true definition is. As I said I'm sorry you felt you needed to take the discussion along the line you did.

dlutter

Sorry to have gotten off track per your question of crush. As I said rules of thumb are simply rules of thumb. Any given std chambered rifle might or might not be able to reach max loading per some reloading manual(it does seem to be getting easier with newer books). If you measure various cases you can find differences between brands as high as the normal increase gained from an AI conversion.

Most reloaders if they don't have data for a given case AI or wildcat will pick the closest they can find and adjust the load tables for difference in case volume. This data just like a loading manual is a guide. No one should ever assume their rifle will allow them to load to table max.

If someone asks me for unknown AI data I will tell them to take their % in capacity increase and increase a table by that amount. Then start low and work up. No way should they assume they will reach that max load. An AI case will hide pressure well so most people end up loading to pressure higher than they would normally. Pressure is still there even if it doesn't show.

quote:

Originally posted by Hot Core:

quote:

Originally posted by dlutter:
You are right, Case Head Expansion is the silver standard (gold standard being a pressure barrel). ...

Hey DLutter, The problem with ANY Haphazard SGS used at home is they can not be Calibrated, and you must use Guessed-At Dimensions, unless you have access to a $$$HIGH$$$ CMM with a l-o-n-g Probe. Therefore all the info(certainly not Data) is pure speculation.

quote:

I still feel a chronograph is a necessity as it is one more thing to tip you off you are getting too hot.

Due to that unknown variation, how would you know when a Load is too Hot with a Chronograph?

HotCore,
I don't know the lingo enough to understand SGS or CMM but was unaware of a for-home-use pressure barrel. I was just speaking of a pressure barrel(I'm guessing it is the CMM with a long probe you mentioned) in a lab/professional setting. I am sure there is no way that "Joe Blow" could accurately measure pressures.

As far as knowing when a load is too hot with a chronograph:
I have read (probably in a gun rag) that velocities will tend to pleateau(or you get less of a gain) when max is reached. Based on your post,I am betting that is not the case.

Still to persist in my point: Would it not be helpful to know that if you got a velocity much higher than expected you may have too hot of a load? Also if you were getting expected velocities you would know you couldn't push it much further?

I am not saying you can infer anything about pressure from velocity, just that you might get hints of where you are at.

Thank you for teaching me a little. What method do you use to determine a max load when working up loads for your wildcat/improved cartridges?

I'm not surprised the discussion got so heated. It seems like every thread on improving a cartridge gets pretty hot. No worries, its all good.

quote:

Originally posted by ramrod340:
If someone asks me for unknown AI data I will tell them to take their % in capacity increase and increase a table by that amount.

How do you know what % in capacity increase do you get with a particular cartridge? Do you just have to fireform, fill the parent case and the improved case up to the top and calculate the increase? If so, this would go along with my original post in that you just can't assume your improved cartridge will have a 6% increase because of multiple variables. It is possible you may only get a 2-3% increase.

Otherwise it looks like I understand what you have been saying.

quote:

I have read (probably in a gun rag) that velocities will tend to pleateau(or you get less of a gain) when max is reached. Based on your post,I am betting that is not the case.

Sometimes but I've also seen the gain go through the roof. SGS is strain guage system I believe.

Since I shoot my own wildcats I have no data. I do shoot over a Chono sometimes when I'm working up a load but normally to see if I think a certain powder will allow me to reach a general target velocity. I a digital micometer and measure each case head before and after. Digital allows me to zero and then take a direct reading after.

When I talk about a % increase I refer to taking a given case measure the capacity and fireform resize and measure again. I use water some use a small gr powder. Normal capacity postings are normally water. A given manufactures case will normally be darn close so one rem case is going to be darn close to the next. So I normally just do it once. But going between brands you can see more variance between factory than the actual gain from AI. Norma has normally given me the most capacity to start so increase will be slightly smaller as a %. Many including me often quote 4% from and AI but as you stated actual can very from 3-6%. Larger starting case lower % gain. More parent taper larger %. A 7x57 based case will gain a higher % than an 06. All are rules of thumb your case and your rifle will set it's own results. As I believe I stated comparing your AI velocity gain to another barrel std or worst posted std data doesn't really tell you much. I've had twin rifles in std chambering that varied more than my AI gain.

I have a 280 AI which I got built with a new barrel & hence a new chamber.

I measured the case web expansion very carefully for about the first 300 rounds or so & then for every new load. I could not find reliable loading data 12 years ago (no internet) & so I used the extrapolated case capacity ratios & used starting loads.

Yes, I did try some very hot loads (copied from a magazine) & resulted in great velocity & even accuracy but the primer pockets opened up. I stopped using that powder as the velocity was too low for a max load.

Having tried over 30 combinations of projectiles & powders & measured case web in all of them I find that the direct correlations I could depend upon of high pressure are

Actual case web expansion measured with a micrometer

• Primer pocket expansion - meaning loose fit of new primer
  
• "Hat brim" on fired primers
  
• Measuring the diameter of fired primers

The last three are not precise and accurate measurements but only general indicators. In the last 10 or so years I do not accept even a slightly loose fit of primers. I do not use any hot loads. All primers MUST fit firmly - period.

Regarding "Hat brim" on fired primers, I was surprised to see that I was hot loading some of my factory chambered rifles as well. Backing off 0.5 to 1 grain solved the problem. Dropping 20 to 50 fps was no big deal.

Measuring the diameter of fired primers certainly indicated to me if the primer pocket was normal or slightly large.

All my 280 AI cases (except the few hot loaded ones) were reloaded 10 to 11 times before being retired. I am into my 4th lot of 50 cases.

Excellent info,guys. Thank you very much.

I have not measured case head expansion in any of my cartridges I reload. Probably very luck I am not missing fingers. How much is normal and how much is too much?

I wouldn't waste my time measuring case heads.

Nobody can absolutely correlate case head expansion to pressure either. Differences in brass hardness, volume, composition, times fired and chambers make it a relative measure just like velocity, case condition (primers, ejector marks, etc) and home-applied strain gauges.

It is no better than any of those other methods.
This guy pretty convincingly shows PRE/CHE are unusable by themselves. PRE & CHE, RIP

In the end, the only thing that matters is if your brass is holding up satisfactorily.

OH crap now we are going to get into a contest over the various Denton articles.

quote:

Originally posted by ramrod340:
OH crap now we are going to get into a contest over the various Denton articles.

quote:

Originally posted by dlutter:
I don't know the lingo enough to understand SGS or CMM but was unaware of a for-home-use pressure barrel. I was just speaking of a pressure barrel(I'm guessing it is the CMM with a long probe you mentioned) in a lab/professional setting. I am sure there is no way that "Joe Blow" could accurately measure pressures.

Hey DL, We do not have to agree about everything in order for you to enjoy your new AI. Just sharing my take on the Pressure issues. Haphazard SGS = Haphazard(this specific word was selected by Dr. Oehler) Strain Gauge Systems, CMM = Coordinate Measuring Machine ($250k and up in a Controlled Environment). You nailed it exactly with a person needing a Lab Environment for using the HSGS. There it can be properly Calibrated with SAAMI Ammo and a Correction Factor calculated to see what the Pressure happens to be. Then it goes from a worthless HSGS to a useful SGS.
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quote:

As far as knowing when a load is too hot with a chronograph: I have read (probably in a gun rag) that velocities will tend to pleateau(or you get less of a gain) when max is reached. Based on your post,I am betting that is not the case.

Actually, it is True for some specific Loads, but some combinations do not always show that Plateau until it is beyond normal Pressure Limits. So, it can work, but might get a person beyond where he wants to be, that was "only" looking for the Leveling out or Plateau(good descriptive choice of wording).
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Still to persist in my point: Would it not be helpful to know that if you got a velocity much higher than expected you may have too hot of a load? Also if you were getting expected velocities you would know you couldn't push it much further?

I agree it would be excellent. The problem is knowing what the "Expected Velocity" should be for your barrel, not the Test Barrel, nor someone else's barrel. It makes no difference if it is a regular Chamber or if it has been Wildcatted. Just no way to know what "should be expected".

The argument being, look in a Manual and you should always be within 300fps +/- of that Velocity. So, if you have a Fast Barrel and expect 300fps higher is OK, it might be Safe. On the other hand, if you have a Slow Barrel and still expect the additional 300fps, you may be trashing Cases with each shot. And subjecting your firearm to unnecessary pounding.
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quote:

I am not saying you can infer anything about pressure from velocity, just that you might get hints of where you are at.

A lot of Chronographs are sold based on that incorrect assumption. Then it is repeated and spread with the Faith of a Southern Baptist Preacher(always with his hand out).

There are excellent uses for Chronographs though. But their best use is found after a Load Development cycle. Huuum, I can see where Vapo would suggest doing it at the same time to observe the Standard Deviation. And I really have no argument with that. If you will be shooting at very long distances, Developing a Load from below to discover the best Harmonic Nodes is what it is all about. And if you happen onto a Harmonic Node with a very low Standard Deviation, then there really should be more consistancy in repeated grouping way out there - Standard or Wildcat.

Chronographs are also fine for comparing Velocities "between" rifles. There is a post on here somewhere(maybe Small Bores) where a guy compared a new 243WSSM to a regular 243Win. The Velocity difference between those two specific rifles was only(maybe) 200fps. Probably not typical, but it was perhaps a Slow 243WSSM Barrel being compared to a Fast 243Win Barrel. Interesting to me.

quote:

What method do you use to determine a max load when working up loads for your wildcat/improved cartridges?

Back when I began, my Elders were primarily into Wildcats. They taught me how to "properly" use CHE & PRE. There are a lot of misconceptions and a lot of total ignorance floating around, disguised as the Truth concerning these old, time proven Methods.

I see where RamRod mentioned "denton" and that must be BECoole's link. If you read denton's bologna and believe in it, then you must also appreciate denton's "The World's Most Ignorant Reloading Suggestion", which finally got him laughed off this Board.
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As to the very best way to check Pressure in a Wildcat, I'd agree with two Methods; 1. Primer Pocket Expansion 2. CHE. The problem with Primer Pocket Expansion by itself is you do not know what is going on until after the Case Heads have already been subjected to enough Pressure to cause the Expansion and thus create "Loose Primer Pockets".

If you have an abundance of time, you can Load a few at a specific Level, shoot them, Reload them, reshoot, reload, etc., 8-10 times and if you have no Loose Pockets, you know the Load is OK. Then increase the Load a bit and do it all over.

Or, you can Load up a bunch at different levels, shoot (over a Chronograph if you desire), get home and determine where the Primer Pockets start becoming Loose. Then trash the ruined Cases, drop back 2-3grains and shoot, reload, shoot, reload, etc., and see what the cumulative Hammering effect of the Pressure is.

Or..., you can measure CHE as I described in the Link and know when to Stop before any Cases are trashed. Chronograph or not.
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So, how to select who is correct between a guy who thinks "The World's Most Ignorant Suggestion" is a great idea and runs Biased Tests to skew the results toward his position, or someone who has said, still says, and always will say CHE(and PRE) can't be beaten???

Perhaps a Totally Unbiased Comparison Test between the totally worthless Haphazard SGS and the old-faithful, never-fail, relatively-inexpensive, repeatable CHE would help. In this Comparison Test we had a relative newcomer to CHE(Kelbro) facing off against a hard-core, HSGS user who believed the only way to know anything worthwhile about Pressure was to (totally waste) spend $$$LOTS$$$ on a HSGS. I refer to that thread as the GLOATING Thread where a relative Beginner to using CHE totally destroyed the HSGS info.
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That is basically it. Follow the Link I provided, or shoot and reshoot while checking Primer Pockets.

Best of luck to you.

quote:

spread with the Faith of a Southern Baptist Preacher(always with his hand out).

Has reloading become that precise now?

With a chronograph, you can start with reloading manual recommended starting loads. Using the reloading manual max velocity as a sanity check, you can work up to your target velocity without trashing any brass.

You are going to experience max case life at a velocity somewhat below the max velocity listed in the manual.

HotCore-Thanks for the help. Looks like I have a bunch of reading to do. FWIW, not looking to agree or disagree. Just looking to understand.