hey everyone after fighting my ruger no.1 7mm stw's accuracy problems I have decided to rebarrel it. I plan on going with a lilja barrel in a #5 contour but I have a question. Would there be any benefits from ackley improving the stw?? any help would eb great. thanks

Very little to offset the cost of new dies, fireforming etc.

In an 06 case the gain at equal pressure is 1% velocity for each 4% capacity gain. When you get to the 7mag it goes down to less than that. The bigger the case the less gain.

Just changing a case to Ackley doesn't guarantee smaller groups you will get increase velocity,case capacity and less trimming.

Ramrod340 has quoted John Barsness as to what is called equal pressure on the parent case and John has his followers.

I've pretty much done the standard type AI done one odd ball 338-280AI. Reamers are always a problem for the odd calibers and that adds to the cost, dies aren't bad as you can forward a print of the reamer and have dies made.

I pretty much average around 10% gain in case capacity 8-10% increase in velocity. I've never done a case in 70 plus grains so cann't honestly say what the gain would be. What I would look at is doing the 7STW if thats what you want but change it over so the headspace is on the shoulders might want to talk to Tim North of Broughton barrel about what kind of gain in velocity you would get using one of his 5c barrels http://www.rifle-barrels.com/.

Well good luck

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Ramrod340 has quoted John Barsness as to what is called equal pressure on the parent case and John has his followers

I'm quoting my own pressure testing results. I agree people often see larger gains but I never saw them at equal pressure.

Simple example a 300Wby has a 47% greater case capacity than the 06. Plus 5000psi. However comparing the listed max loads in the Nosler manual for a 180 between the 2 you get a 11% velocity increase.

Compare the 300Wby and the 30-378 the gain of 31% capacity gives a 2% velocity gain from the same manual.

I've built numerous AIs and full wildcats over the years. In an 06 based case my gain in capacity was around 4-5% or the 7x57 case closer to 7-7.5%. It takes a Gibbs(shoulder forward) for me to get 10+%. My full wildcat is the 280 case shoulder moved way forward and 40deg. I gain 11% comparing same brand of case before and after. I've also see 3-4% gain in STDs just by switching brass.

I've taken a lot of loads past the point of losing a primer while pressure testing. Only thing I will quote is in my experience at equal pressure you get 1 for 4 from the 06 less for larger and more for smaller at equal pressure. I for one no longer feel the need to push my cases and luck into the 75,000 range. I see no need for it.

honestly I am not so much looking for more speed because the stw is pretty fast already. I am looking for the same speed with less pressure. I am also interested in more accuracy of course and longer case life. I have found the reamer already but I am unsure if this is worth the trouble or not??

You enlarge the case you will have to burn more powder to reach the same speed. You might be able to reach the same velocity with slightly less pressure. It will not be much. If you are headspacing off the shoulder with the std then the AI version will not really give you any greater case life in my experience.

I've owned more AIs and wildcats than stds but I sure wouldn't spend the time or $$ to do it on an STW.

Sorry guys; know it's not a wildcat, but why not go to the 7mmRUM. Lots of case capacity

the 7stw IS already ackley'ed... not much gain, if 2-3% i would be stunned

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I've built numerous AIs and full wildcats over the years. In an 06 based case my gain in capacity was around 4-5% or the 7x57 case closer to 7-7.5%. It takes a Gibbs(shoulder forward) for me to get 10+%. My full wildcat is the 280 case shoulder moved way forward and 40deg. I gain 11% comparing same brand of case before and after. I've also see 3-4% gain in STDs just by switching brass.



I'm sorry for the misquote but my first wildcat was a 7x57 and I got my loading data for Speer's #4 wildcat manual dated 1959. Using 53gr of IMR-4350 and 145 gr speer I was just over 3000fps back in them days for a standard 7x57 that I loaded for around 47gr was a max load using 145gr bullet velocity was around 2600fps plus. I was also shooting a 7mag and with bullets up to 150 grs I could come pretty close to with the 7x57AI. The case capacity of the 7x57 is 55.55gr water and the 7x57AI is 61.44gr water

I tried to follow your percentage but I got lost so if you could give your loads,velocity as compared to your standard loads in the 7x57 it might help.

My 280 case are Rem and they hold to the top of neck 58.9gr of IMR-4227 case for my 280AI to the top of the neck with IMR-4227 hold 63.1gr a new Nosler 280AI case hold 62 grs with a Kreiger barrel using 150gr bullet I can get over 3100fps, in my standard 280 I had a 22" barrel and I was in the 2800fps range with a 150gr bullet.

One of the things I've always done if building an Ackley is shoot the parent caliber. The gain in velocity just happens to be part of building that type of rifle and loading for one is no different that any caliber, you have a start load and max and nothing says you have to load at max. Normally the starting load for the Ackley is the max load for the parent caliber.

I only state what I have measured. Comparing same brand water capacity of my 7x57 & 7x57AI I get 57.1 and 61.4 or 7.5% In 257R the numbers are 58.2 and 62.4 or 7.2%. In my Norma 280 brass it is 68 and 70.8 or 4.1% and my 280PDK 75.1 or 10.4%. I do have info that calls the 7x57 55.55.

A lot of my testing was with pressure equipment. In the 280 I took a 23" Mcgowan 280 barrel shot it and got a reference point. Then ran a AI reamer in it and worked up to the same pressure then did the same for my 280PDK.
Velocities were 3090, 3125 and 3180 or 1.1% and 2.9% increases.
So in the AI a 4.1% capacity gave a 1.1% velocity increase or 1.07 for 4.
IN my 280PDK a 10.4% capacity gave a 2.9 velocity increase or 1.1 for 4.

I did the same comparison for several other AIs. The 7x57 based cases gave a little higher than 1 for 4 the 243 based lower.

I had to get to the point of losing primers to reach many of the various posted and published AI velocities. I simply choose to limit my loads to the 65,000 range.

So I can only say in my pressure testing at EGUAL pressure a 1 for 4 was the norm.

quote:

Originally posted by ramrod340:
I only state what I have measured. Comparing same brand water capacity of my 7x57 & 7x57AI I get 57.1 and 61.4 or 7.5% In 257R the numbers are 58.2 and 62.4 or 7.2%. In my Norma 280 brass it is 68 and 70.8 or 4.1% and my 280PDK 75.1 or 10.4%. I do have info that calls the 7x57 55.55.

A lot of my testing was with pressure equipment. In the 280 I took a 23" Mcgowan 280 barrel shot it and got a reference point. Then ran a AI reamer in it and worked up to the same pressure then did the same for my 280PDK.
Velocities were 3090, 3125 and 3180 or 1.1% and 2.9% increases.
So in the AI a 4.1% capacity gave a 1.1% velocity increase or 1.07 for 4.
IN my 280PDK a 10.4% capacity gave a 2.9 velocity increase or 1.1 for 4.

I did the same comparison for several other AIs. The 7x57 based cases gave a little higher than 1 for 4 the 243 based lower.

I had to get to the point of losing primers to reach many of the various posted and published AI velocities. I simply choose to limit my loads to the 65,000 range.

So I can only say in my pressure testing at EGUAL pressure a 1 for 4 was the norm.

Here is a quote from Ackley in Speer #4 manual on the 7x57AI. "P. O. Ackley, however, says he does not care what pressure are so long as he does not have extraction trouble or primer leaks, and he says that the straight body facilitaes extraction and prevents undue backthtrust on the bolt." In that he is probably correct and more and more ballisticians are incline to agree with him. No pressure data for this cartridge is, of course, available, but experienced observers believe top pressure to run around 60,000psi or perhaps more. Now that from 1959 so what psi are you running with the 7x57AI and what type pressure equipment are you using? IMR published pressure for the 280AI and that runs around 60 to 61,000psi the 30-06 is 57 to 59,000psi. Hodgdon list starting/max loads and pressure and a reloader can figure out pretty close as to this amount of powder vs velocity/presure and that velocity can be confirmed by chronographing.

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Now that from 1959 so what psi are you running with the 7x57AI and what type pressure equipment are you using?

I figure since the 6mm pressure is 65,000 the same case in 7mm should handle the same. I basically load everything with a 65,000 max.

My smith had a strain gauge system that I later replaced with an Oehler Model 43.

A friend of mine developed an improved 7STW a few years ago called the 7mm Olsen. He blew the shoulder forward and gave it minimal taper with a 45 degree shoulder. I barreled up a 700 for him and it's pretty imperssive. 160 Noslers at around 3300 fps.

quote:

Originally posted by ramrod340:

quote:

Now that from 1959 so what psi are you running with the 7x57AI and what type pressure equipment are you using?

I figure since the 6mm pressure is 65,000 the same case in 7mm should handle the same. I basically load everything with a 65,000 max.

My smith had a strain gauge system that I later replaced with an Oehler Model 43.

http://www.oehler-research.com/m43faq.html

I do question how accurate the pressure test is with the 43 as compare to other ways and that is pretty well explained from Oehler in the above post.

Your test are only related to your rifles.

quote:

Your test are only related to your rifles.

AS I've said everytime I post my findings in my rifles same barrels I measured a 1 for 4 increase at equal pressure. I don't care if that pressure was 60,000 or 65,000 just that it was repeatable. I did have a number of my loads run through a bullet manufactureres pressure system. Allowing me to slide my data.

In a tight STD chamber and tight AI chamber I found the same case to fail at basically the same pressure. With my equipment that was in the 73-75,000 range. In offical equipment that might be 68-70,000. I see the relationship as more important than the actual number. I also found the window from the point you would first see the normal pressure signs to failure was greater with greater body taper. So in a std case often that range was 1000s of psi in the AI that window was 100s. From first sign in the std case to failure was 2-3 grs in an AI sometimes .5gr. So in a way I agree the AI handles the pressure better. Actually it simply doesn't show it until the head is ready to expand the pressure is still there. So a normal reloader watching for signs would load to several 1000# higher pressure. Resulting in more than a 1 for 4 gain but due to pressure not capacity. Is it safe? People do it all the time. PO swore by it. I simply don't care to. I don't want to have to worry that my load is safe at 70deg but will blow a primer at 90. A few FPS isn't worth it to me. I can load to the 65,000 range per my equipment. I have no issues with case life and my loads are just as safe at 110degs as they are at 0. I simply share my findings as a data point.

There is plenty of AI data that gives huge gains. Everyone is free to use whatever they are comfortable with.

In my experience the Model 43 gave me a far better idea of where I was related to case failure than simply looking at the fired case. Could I use it to say per SAAMI a given load was 63,450psi. Nope. For my work I didn't need it.

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Would there be any benefits from ackley improving the stw??

NO! I have no idea what's wrong with your accuracy, but the 7 STW is over bore capacity for the caliber to begin with, and such rounds are often very difficult to find an accuracy load for. Yours may be one of these. It may NOT be the barrel's fault at all.

I'd recommend you cut your new chamber of a 7mm Rem. Mag, .280 Rem., or even the lowly 7X57. Both are easier to develop good loads for, especiually the little one..... (this is merely a joke, as I realize that you cannot be content with the performance of a 7X57....)

I have a mark bansner built7mm STW with a 1/9, 26" lilja that will run 160's at 3340 fps. the load is rem case/fed 215/94 gr WC872/ 160 accubond.
some barrels are just faster, the best bet now adays is a broughton 5C, they seem to average higher vels than most others and shoot very well
Ya want 3500 fps, go with a 7mm AM, mine will run a 160 accubond to 3600+, burns way more powder than an STW though.
RR