Going to help a cousin rebarrel a Savage to 257 AI. Will a 257 Roberts Head Space Gauge Work?
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Going to help a cousin rebarrel a Savage to 257 AI. Will a 257 Roberts Head Space Gauge Work?
Can't answer the question but Manson reamers used to have a good dissertation on the Ackleys and head space I believe.
Try:
https://mansonreamers.files.wordpres...ey_gaging1.pdf
FWIW
Oh boy...Typically, an AI go gauge is .004" shorter than a parent case go gauge. This is done so a parent case loaded round will chamber, the brass will be pinched in place at the neck/shoulder junction, and the round will safely fire. The .004" dimension is assumed to be correct, but brass brands can vary in thickness and some may chamber easier or harder than others. This is the whole concept of the shorter chamber.
Some time ago, I got into a lengthly exchange here about just fireforming brass in anAI chamber that was headspaced with a regular go gauge. The issue at that time was for a 280AI, which has many different varieties. Regardless, my point was, people fireform brass in modified chamber all the time if they pay attention to what they are doing. The most popular case in point in today's time is the Dasher case. The shoulder on a Dasher is a full .100" forward of the parent BR case, and foreforming takes a procedure to hold the case in place while it is fired. Tow methods are commonly used. One is seat a bullet long where it is jammed hard into the lands, and fire. The second is to expand up the neck of the case, then size down the top of the case until the bolt will close, creating a false shoulder. Either way works.
So if you don't reload and shoot factory brass, get an AI go gauge. If you understand about fireforming, then a parent go gauge can be used.
Here we go....
I suppose the first question is, are you going to set the barrel back? If not then a true AI gauge will not work as you will be starting out with it deeper than the finished chamber.
First rule of Gunsmithing: use the right tool for the job.
In this case, it would be a set of 257 Roberts AI headspace gauges. Obviously.
http://www.reamerrentals.com/Product...Code=257RA%2Eg
you are100% correct Goodsteel, but in a pinch I have used "Plastic Gage"removed the firing pin & used a loaded round then measured how flat the "Plastic Gage",just be certain that the bullet is not touching the throat
The plasti-gauge might be a bad choice as when using it to measure crank or cam bearing clearances, you can't let the crank turn or you'll widen the strip & get a false clearance. Same thing will happen when the bolt turns I'd think.Quote:
Originally Posted by fivefang
Considering how much factory brass and ammo varies your are better off making your rifle chamber match your loading dies.
When you fit your brass, expand the case neck and then neck it back down to fit your chamber or - start out with a longer case and neck it down to fit.
Right now .257 Roberts brass is unobtanium so the AI feature using factory ammo may be worthless in the future.
6mm Remington/.244 Remington still out there. Have necked up & fireformed a bunch of that stuff for my .257 AI. 7mm Mauser is the parent cartridge for the Roberts & then the 6mm/.244. Not any big deal to make really. For some reason, you don't hear much about those cattiges anymore. .243 Win still going strong but 6mm Rem. kind of a sleeper.Quote:
Originally Posted by EDG
Don't believe a std Roberts head space die would work for AI. Without pulling out appropriate cases I believe the AI case will be longer than the std case. This is the result of the sharper taper of the front of the case.
16 years ago in Yahoo gunsmith list this question went on for 100 posts and 6 months.
This was of some interest to me, as I had just built a 257 Roberts Ackley Rifle on a VZ24 action, using a new piece of Winchester 257 Roberts brass as the go gauge.
This would be shorter than a real 257 Roberts go gauge, but not short enough.
If I tried to form cases, I got a split behind the shoulder.
Yes I could pull the barrel and take 0.004" off the breech and off the shoulder.
But I started experimenting with forming brass.
100 experiments later, I had a system:
1) Lubricate the outside of a case with moly grease [50,000 psi grease as my father would call it]
2) Put 10 gr of pistol powder in the case
3) Fill the rest of the case with instant cream of wheat [COW as handloaders on the internet call it]
4) Shoot straight up or seal the case mouth with a poke into a bar of Ivory soap and shoot horizontally.
5) Resize the neck of the formed brass that now has a partial shoulder. Reload with full power and full accuracy.
6) The case now has been fired twice and looks like a 257 Roberts Ackley improved case.
Attachment 164193
Proper gauges are preferred, however, on rifles like the Savage that use a barrel nut most just use new brass/cartridges and adjust until you feel contact with the shoulder. That is perfect for AI chambers.
the purpose of the .257 AI is to be able to fire factory ammo to get cases.
If you begin your .257 AI effort with loading dies you don't need to match a headspace gauge. You only need to match the FL die.
6mm Rem brass due to the sharper shoulder has excess headspace in a .257 Roberts and the AI version would be worse. So you would need to expand the 6mm neck over size and the size back down to leave a false shoulder. All in all starting with 7X57 or .270 brass would be a better idea.
I sold my last batch of .257 brass for a buck each. It was originally bought to make 6mms. By a fortunate turn of events I was able to trade some 45-70 brass for about 300 6mm cases.
Quote:
Originally Posted by Newtire
Cousin bought himself a 257 imp go Gauge. So things should go well.
I just expanded the neck and fireformed these .244's I bought once fired using a cast boolit and they came out just fine. These were made in a proper .257 AI chamber that had the barrel turned back I assume. I bought the gun already rechambered so never gave it a thought. I'll have to keep an eye out but none so far have split after being full length resized and fired with some pretty warm loads once they were fireformed.Quote:
Originally Posted by EDG