do you use a chronograph?

09 June 2003, 09:43

Brent Moffitt

Hot Core,

Appreciate your responding and I was out of line for saying you "wanted" to spread BS, I don't know what you "want." My apologies. It's just that I know it's BS based on "your" experience and data provided with PRE and CHE, "you've" shared this with us over time... it's "not" any first hand experience of "my own" with it, but you "already" know I've not used your method too. As I recall, Denton also has not used the CHE and PRE method of yours and used the data and techniques YOU'VE PROVIDED to base the conclusion that strain systems is more accurate. Why do you insult my intellegence and say I need to try the PRE and CHE method first hand before concluding it isn't as accurate, after all I'm stating your data is accurate and worthy of use to determine this, or is your data NOT accurate enough to use as a comparison? If that were the case, well we won't go there... but if you want logic, we and others can see who's logic breaks down pretty clearly. You make an issue out of me using your data to base a conclusion, you've never done this, and I'm wrong to do so????? If I felt there was something wrong with your method or data I WOULD. What is wrong with the PRE and CHE method that makes it less accurate though, is that even if you do it all correctly there are VARIABLES BEYOND your control.
You talk about my lack of experience when you don't even know what experience I do have, why is this?
Are you trying to paint me into a "rookie" as to discredit me for some reason? If so, I'll save you some trouble... there's ALOT I can learn STILL. Knowing that explains in part WHY AND HOW I DO. [Wink]

A KNOWITALL DOESN'T BELIEVE HE NEEDS TO LEARN ANYTHING AND THERFORE DOESN'T.
You are obviously smart enough to see the resolution and unpredictable variables in each of the methods used.

You said;After following your posts for awhile, I now understand you are quite often negatively critical of things where you have ZERO first-hand experience or actual knowledge. What are you refering to specifically, and how is it you know what I know or have experience with again? I can say you are way off base and don't know me that well at all, pal. You point it out though.

5. You are at the most dangerous phase of Reloading - you have some "limited" knowledge and "very limited" experience. Due to your Rookieness, you end up making statements which are simply not true and you don't know it. Then when someone bothers to point out the errors, you defend them with personal attacks and speculation.

Not wise at all. But, as you can see, I can dish it out as well as I can take it, with one added bonus - my statements are based on LOTS of knowledge and over 4 decades of experience.

Again, you make ASS-UMPTIONS as to my knowledge and experience being limited to ZERO, something you even know VERY little about, and wouldn't ya know, that's all you did with that statement of yours.

I think most people can think for themselves and say weather my comments are unfounded, I usually take the time in the post to explain why the are founded. I'll take the critisizim when they sound off though, as I did from you.

Look forward to your posts, I usually get something good from the ones I see. Don't be so thin skinned, we're all men here. [Wink]

I can take it, so dish it out some more if you feel like it, don't hurt my feelins any.
I still say NO when my wife wants to handcuff me to the bed and have her way with me though. [Big Grin]

Take care

09 June 2003, 12:53

Hot Core

quote:
Originally posted by 6.5 Bandit:
Hot Core or someone can you please explain PRE/CHE. Not to be ignorant but I am not familure with this.. Thanks

6.5 Bandit

Hey 6.5 Bandit, Lots of things I'm ignorant on too, but Pressure Indicaton is not one of them.

PRE/CHE is Pressure Ring Expansion and Case Head Expansion which are both viable Pressure Indicators. These methods have been used over 100 years and work extremely well, are quick to grasp and don't cost an arm and a leg.

When compared to other Pressure Detection methods, PRE/CHE are pretty much in a league of their own. That is because you get "First Hand" Pressure Indications directly off the cases being fired. There is a learning curve and there are limitations, but they are easily addressed and quickly overcome.

You can use PRE with any cartridge; pistol, revolver, rifle or shotgun. And you can use CHE with "most" of those. CHE can not be used on some cartridges relegated to very low operating Pressure by SAAMI, simply because the Case Head WILL NOT Expand at those Low Pressure levels.

You can find excellent write-ups concerning these methods in Ken Waters' "Pet Loads" and Bob Hagel's "Game Loads and Practical Ballistics for the American Hunter". There are no finer Gun Scribes in the business.

Shouldn't be long before our "Denton" has an article on these methods in the magazine he writes for. He is unbiased and I predict he will see the value of both methods.

Basically you need a box of Factory Ammo and a 0.0001" capable Micrometer to establish a Benchmark for the PRE. You fire the rounds and then rotate the Pressure Ring between the Micrometer anvils until the Pressure Ring will "hang".

NOTE: This is not the typical way Micrometers are used. But, we are looking for the finest accuracy possible from the expanded case and this is one of "my tricks" to enable you to get that accuracy. You will not find this "trick" in either Mr. Waters' or Mr. Hagels excellent information.

For example, lets say you measure 0.4230" across the Pressure Ring and it will "hang". But if you open the Mic to 0.4231" the case will not hang. So you record 0.4230" as one PRE value. Do that on the entire box and average them. The number you get will be your Benchmark for "that Lot of cases".

You must either Full Length Resize or Partial-Full Length Resize the cases to realign the Pressure Ring. You can not Neck Size while Developing Loads using this method.

Then reload those same cases and as you shoot record the PRE. It is best for folks just beginning to use this method to STOP adding Powder when the PRE created by their Loads matches the PRE of the Factory Ammo.

Then back off the Load slightly and fine tune your groups by adjusting the Seating Depth which directly effects the barrel harmonics.

You can "usually" use those same cases 5-9 times before work-hardening will affect your PRE values. The reason for the wide spread is it depends on the "strength" of the Loads you are testing as to how much the case is work-hardened.

CHE is explained rather well in the "Forward" of most Speer Manuals. It is not quite as accurate as PRE, but I use both(as well as the other Pressure Indicators available to me).

CHE works well on Belted Cases, but on Non-Belted Cases you are best served with a set of "Thin Anvil(Blade)" Micrometers. This is because the case rim will often interfere with the reading. And, you can file down the rim slightly in two spots directly across from each other and use CHE that way.

When using CHE, measure the Case Head prior to firing from "one specific spot" and record the value. Do not rotate the case like you do with PRE to locate the widest spot. After firing, remeasure that same exact spot on the Case Head and record that value. The "difference" between those two readings is the CHE.

CHE can NOT be taken on the first firing of a case because the data will be very skewed. But, you can use it on firings 2-9, again depending on the strength of the Loads being tested.

That is basically it. Oh yes, you MUST USE 0.0001" capbale Micrometers. The 0.001" capable Calipers just are not accurate enough for taking these measurements. You can get the RCBS 0.0001" capable Micrometers from www.wideners.com for $21. And I got a Graff catalog last week which also shows a $21 set, but I don't remember the brand name.

Quite a difference from spending $2000 on a M43 and a Laptop to run it.

One of the largest advantages of using PRE is you get to use the benefits of the multi-million dollar Factory Ammo Test Labs to set the upper Pressure Limit for the cases. You don't have to do any "guessing" or make "gut feel" decisions. And you do not need to screw-up your firearm by gluing Strain Gauges to it.

Just STOP when the PRE of your Loads matches the Average PRE of the Factory Ammo and you have reached the SAFE MAX for that combination of case/primer/powder/bullet.

Nothing tricky or complex at all.

Best of luck to you.

09 June 2003, 14:06

6.5 Bandit

Hot Core,

Thanks... Thats one way I havent checked for pressure to be honest.. Allthough I have heard this method before just never heard a whole lot about it.. To be honest I just always used the flat primer/sticky bolt/extractor markings etc.. method.. [Big Grin]

6.5 Bandit

09 June 2003, 23:48

Hot Core

quote:
Originally posted by 6.5 Bandit:
Hot Core, Thanks... I just always used the flat primer/sticky bolt/extractor markings etc.. method.

Hey 6.5 Bandit, You are welcome.

I also watch for the "flat primer/sticky bolt/extractor markings etc." you mentioned. But I rarely get to those Pressure Levels because the PRE/CHE measurements STOP me before I get there.

I do agree those are valid Pressure Indicators in new modern bolt actions. Only real problem is that you are well beyond the SAFE MAX when you see them.

Some of the older cartridges I've used in years past never got to a high enough Pressure to trigger any of those Pressure Indicators though. And I have a 444Mar rifle that is not designed to reach the "flat primer" pressure levels. So, I have to use PRE/CHE to know what is going on in the case.

By the way, on Non-Belted cases, the Pressure Ring is the "widest" portion of the fired case forward of the extraction groove.

On Belted cases, the Pressure Ring is the "widest" portion of the fired case forward of the Belt.

Best of luck to you.