Question about resizing for an AI chamber

[TheSilverSlayer]

Greetings all. 

I have a 1948 FN Mauser chambered for .270 AI.  I bought the rifle before I knew much about guns, and it was sold to me as a standard .270 win.  Anyway, I have put roughly 350 rounds through this gun without a hitch.  As some of you know, AI dies are expensive and hard to come by.  My question to you all, is if the fired cartridges chambers easily, is there any reason why I should FL resize?  The 300 rnds I put through it were primarily core-loks.  Upon extraction of a fired (and thus fireformed) case, I notice the cases have a fairly noticeable expansion ring just above the case head.  This makes me rather hesitant to attempt reloading these cases.  I checked out some new, unfired core-loks, and they measure .464" where the expansion ring would be.  Fired cases show an average of .470".  Fired cases show no other signs of danger save for very slightly flattened primers.  Based on the data I have provided, would it seem as though these cases are reloadable? If so, is it considered a safe practice to neck size only for this particular caliber?

[charles p]

Don't think you can use a standard 270 sizing die for an AI case, but you can try it.  It might just squeeze back into shape.  The brass muxt flow somewhere and it will probably go to the neck.  If your AOL is too long, then you are loosing brass in another part of the case.  Just purchase the AI dies or sell the rifle.  Any middle ground is probably going to be unsatisfactory.

Not speaking from experience.  I have sized standard brass to AI, but never the other way.   Charles

[Lone Star]

The cases are certainly reloadable.  What you are seeing is normal case expansion in a large diameter chamber.  We can't tell if the chamber was this dimension from the factory or if the rechamber job enlarged the chamber.  But it doesn't matter.  It is common for fired '06-based cases to measure 0.470" or even larger above the rim, this is not a problem.  I have a rechambered .30-06 that expands factory loads to 0.4715" and I reload those cases over and over.

Charles is right, you should not FL resize your AI brass in a normal .270 die!  This will overwork the brass and the cases will be too long to use without trimming.  You can neck size if the cases chamber okay, but you had best get a .270AI die set.

Note that if you are firing regular .270 factory ammo then your velocity will be well below normal for .270 ammo.   To take advantage of your AI chamber you need to reload with the correct dies.


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[mauser98us]

Neck sizing only works great on my 35 whelan Improved

[TheSilverSlayer]

Sorry for the confusion:  I was never intending to resize my AI cases to standard .270.  The main point of my question was to verify the safety of neck sizing only on the AI cases.  Also, I wasn't sure if the cases had expanded beyond a safe limit.  By the sounds of it, they are well within specs.  I mic'd a bunch more and found that most of them were actually .4695", not that it makes much of a difference.

I was worried, because the expansion ring looked much larger then those I've seen on other rifles' brass.  I have read that this is an indication of a potential case-head separation, obviously something I'd wish to avoid.

Lonestar:  Are the AI dies a must?  the cases fireform perfectly.  Would neck sizing not be sufficient?

[Tom W.]

Sooner or later you'll need either to F/L size or discard the case. Until then neck sizing will do just fine.

I had my 30-06 rechambered to 30-06 a.i. and some of the cases I was hesitant to reload, some I just put in my  recycle bucket. The new brass wasn't a problem, my bad cases mostly came from using handloaded  (several times, to be sure) Nickel plated brass. I still checked the trim length on the fire formed cases, altho most didn't need trimming.

[charles p]

I have a better understanding of your question now.  Still I don't know if a case fired in an AI chamber will simply neck size.  The walls of the case will be straighter because the AI chamber will remove the taper after firing.  I suppose the wall deminsion could interfere.  A friend above says he has success with his Whelen, so maybe it will work.  Should be easy to test.  Just take an AI case to a friend who has a standard 270 die.  Lube the entire case to be safe.

[Siskiyou]

When I started reloading the .270 Winchester I did not have a lot of cases and I kept reloading the same cases and started losing a case separation just above the rim.  Externally the separation was not visible.  I found a low cost tool to detect the separation early.

In 1969 I bought the latest version of The NRA HADLOADER’S GUIDE.  The guide contains a lot of helpful hints for reloader’s.  I page 225 of the guide was this helpful hint.  Straightened out a paper clip, and create a slight bend on one end.  The loader can use it as a feeler gauge to detect the start of separation inside a case.  I keep a couple of these feeler gauges on my bench.  You do not know when there will be a National Shortage of paper clips.

I use a pair of pliers to make a ninety degree bin at the end of the clip.  Not required but I follow-up with fine file and bevel the bent part creating a chisel point.  I have detected a problem with a number of cases.

I believe you will get a number of loads out of your cases by neck sizing

I have a brother that has a 270 AI and he has either RCBS or Redding dies for it.  I will ask him for input.  He also has a couple other Improved rifles.

 
I will talk to my brother later, he has a 270 AI, 257 AI, and 35 AI, and he should have some thoughts based on his experience.  The tough part will be getting him off of his latest project.

Have you compared the measurements of your fired cases with drawings of the .270 Ackley Improved, the 270 Gibbs, and they might be a few other versions out there.

[Siskiyou]

I just talked to my brother regarding 270 AI.  He recommends against using standard 270 dies for neck size the improved case.  The improved shoulder has been blown out, and the upper case is a larger diameter then the standard case.  He says you will over work the case.

[Tom W.]

I have a better understanding of your question now.  Still I don't know if a case fired in an AI chamber will simply neck size.  The walls of the case will be straighter because the AI chamber will remove the taper after firing.  I suppose the wall dimension could interfere.  A friend above says he has success with his Whelan, so maybe it will work.  Should be easy to test.  Just take an AI case to a friend who has a standard 270 die.  Lube the entire case to be safe.

Not wanting to rain on your parade, but He doesn't want to resize the case back to standard dimensions, just wants to necksize the case... unless I mistakenly read the post...
I do know that a case fired in an A.I. chamber can simply  be  neck sized, altho after a time an A.I. F/L sizing die will be needed. At least I bought three dies from Redding... F/L, N/S, and Seating......But then, that's my understanding...

[TheSilverSlayer]

I have ackley's handbook for shooters and reloaders, and the only time he mentions the .270 AI is to say that it is basically not worth doing.

Back to the expansion ring issue.  Some have said the expansion is within an acceptable range .4695" - .470", while others have said to check with a paper clip gauge.  When using the paper clip gauge, how is one to know when a case separation is eminent?  Will it hang up strongly as if it as hit a crack, or will it be more subtle?

Also, is there a universal neck sizing die that works for all .277 calibers? Or is this just wishful thinking?

[Siskiyou]

You will feel the paper clip grabbed the area where it is separating.  Run the paper clip up and down the upper inside of the case to get a feel for how it should feel when it is okay.  If in doubt run it up and down the outside of a good case so you will recognize the difference.  A case starting to fail might give you are subtle indicator other times it will be pronounced.  When in doubt I dump the case.

In discussing the improved case with my brother says the standard .270 case loses some of it taper when fired in the AI chamber.  Logic says that when the case progresses up the die even for neck sizing that the standard die will partially resize the walls of the case.

I have a lighted magnifying glass on an extend arm at my reloading bench which I use for exterior case inspections.

Do your cases have the Ackley 40° shoulder after firing?

I have always been a little enthused about the .270 AI, but have heard disappointing reports or heard great results.  The problem is that nobody has used a Chrony to measure his results. 

I have challenged my brother on the issue a number of times.  He has a Chrony and I made him new rods to hold up the deflectors.  But he has never fired the 270 AI a crossed it.  I have always thought the advantage would come from long 150-grain bullets, and slow burning powder.

[TheSilverSlayer]

I have heard the velocity improvement are minimal. 

In fact, on page 90 of Ackley's "Hand Book For Shooters and Reloaders", he states "Since the original .270 is over bore capacity, little improvement can be expected although some shooters say it is a fair cartridge for bullets heavier than 150 gr. Due to it's relative inefficiency it is not recommended. The standard .270 in unaltered form should be better, therefore no loading data is given"
This is from the 1959 edition.

I am fairly certain the cases have a 40 degree angle, but I have not measured them. 

[TheSilverSlayer]

A little off topic, but if you click on the pic to view it full size, you can see a factory imperfection on the live round right near the neck. Any have this happen before?

[Tom W.]

Don't quote me on this, but I believe Hornady's neck sizing dies are caliber specific, as opposed to case specific. I know that I can use one die for both the .308 and the .30-06, and I would imagine that it would work for my A.I, altho I haven't tried it yet.

[Savage]

Here's some info that might be helpful. This guy has the 30-06 AI, but talks about necksizing and the dies he found necessary to reload.
http://www.longrangehunting.com/forums/f17/270-winchester-ackley-improved-22420/ Specifically post # 6
Savage

[Siskiyou]

The unloaded case that is pictured sure looks like an Ackley case. 

The shadow on the factory case makes it difficult to see the damaged neck.  Looks like a mis-alignment in a loading machine, and case was damaged when the bullet was seated.
 
I did save a copy of your picture to run by my brother when he visits sometime in the future.  We talk on the phone, but I do not trade e-mails with him.  My young nephew attracts virus, going to internet gaming sites looking for cheat codes.  When he comes to visit the machine he uses it disconnected from the Net.

My brother offered to bring his 270 Ackley with him and let me shoot it on his next visit.  It was a kind offer but I told him that he needed to take it out and fire his loads across his Chrony.  That is the data I want.  Does his load show a usable gain, loss, or duplicate factory 270 Winchester velocities.

At times he has a short attention span when it comes to his wildcat rifles.  He has a number of starting points, in this case I believe he started with a factory chamber and had it re-cut for the Ackley case.  He purchased 270 Ackley dies, and some 270 Ackley cases.  He has also created some cases firing factory ammunition.  His attention was then diverted to a 6.5-.284 Winchester project.  He already owned standard .270 Winchester dies.

It would be interesting to do some load testing for the .270 Ackley.  I would start with 150-grain bullet.  Near maximum loads of H4831 come close to filling a .270 Winchester case along with 785, and WMR.  In my rifles the combination provides top velocity and accuracy.  Will there be a velocity gain with the .270 Ackley case using H4831, 780, RL-19 and RL-22.  http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/43

The 270 Ackley project had become a footnote in a procession of wildcat rifles, build them, load for them, shoot them, and forget them for the next project.  He is like a sailor in a new port.  He would kick my butt for that.  Okay, a marine in a new port!