Question about Fire Forming 257 bobs into 257 AI

[Hugnot]

So I am a newby at fire forming. For any out there that fire form cartridges...

I picked up a 257 AI by sheer accident in an auction. Rifle was obviously a customized left-hand hunting rifle with a Savage 110C action when I bought it. After I received it my FFL dealer and I took it out to the range and fired a new Hornady 257 Roberts round through it. We examined the spent cartridge and notice it fire formed into an AI round.

He indicated that I needed to go out and fire form about 100 257 Bob shells and reload them for the AI with the hunting bullet of my choice. I took five boxes of cartridges out this weekend to form. of the 40 rounds I shot, one cracked at the neck as was expected, but two ruptured near the base (see photo).

Half of these were reloads and may have been too hot. The three ruptured shells (bottom 3) were all reloads. The factory loads were "silver tips" and appeared to work just fine (see #2 from top) I had to stop at two boxes because rifle was getting hot and because each time the shell ruptured at the base, the bolt could not extract the shell and I had to remove and clean the extractor and ramrod the shell out.

Are the reloads too hot or is the a problem with my headspace being to large? I don't want to ruin this nice rifle.

View attachment 278517

I don't think you have a headspace problem:

This is what excess head space brass failure looks like:

The brass on the bottom shows indications of impending failure. The one on top has failed.

Compare your photos with these.

Your problem is not excess head-space, in fact the headspace in your rifle might be within spec. Should the head-space on your rifle check out destruction of brass is likely to continue with a profound loss of brass & those expensive scarce primers. Subtracting the cost of components used up to make useless .257AI brass from the cost of a new barrel would be of little importance. Throwing money at the problem won't fix it - measure the chamber before buying lots of expense brass & primers.

 

[MNbogboy]

It's been awhile since I ordered from them so I appreciate the head's up on their current status.

I have 2 257 Bob Ackleys and 2 6.5/257 Bob Ackleys. I always formed brass from 270, 25-06 & 30-06 brass by extending out a longer neck & then trimming to .010 over Roberts length. The longer necks usually shorten case length from .009 to .020 when fireforming. I also made brass from Roberts brass & 7x57 mauser. Had good luck with 8x57 mauseralso.
Annealing neck shoulder area is mandatory when extending down the longer 06 based cases.
A while back on a whim I created a 6 dasher case for a friend by shortening a 243 case to dasher length. Then converting the 20° shoulder to 30° in a 6.5 creed die. Once the 30° shoulder was in place I then formed it to 40° in an Ackley die. Nosler can form 280 Ackleys with their processes. Made me think we can form 40° shoulder angles with the correct sequence of steps 20°-30°-40°. Seemed to work ok without a lot of time or effort.
Never have tried cow but fireform loads using the bullet you plan on down the road and standard Roberts powder charges will form you some nice looking Ackleys. Also seating depth tests can be done while fireforming. Barrel break-in is also accomplished simultaneously. The fireform loads usually will show accuracy capability of the barrel also.
Have fun with the Ackley.
This post makes me want to try a few more things.
Good luck,
Randy

 

[Seabeeken]

I don't think you have a headspace problem:

This is what excess head space brass failure looks like:

View attachment 278993

The brass on the bottom shows indications of impending failure. The one on top has failed.

Compare your photos with these.

Your problem is not excess head-space, in fact the headspace in your rifle might be within spec. Should the head-space on your rifle check out destruction of brass is likely to continue with a profound loss of brass & those expensive scarce primers. Subtracting the cost of components used up to make useless .257AI brass from the cost of a new barrel would be of little importance. Throwing money at the problem won't fix it - measure the chamber before buying lots of expense brass & primers.

I had 1 Hornady case separate like that while forming 250ai brass. New brass is often under size and the firing pin can drive the case forward slightly where it expands, grip the chamber tight enough that the case head moves back and separates. I did 2 things to stop this and never had an issue again. I start with a very clean chamber and very very lightly oil the chamber to prevent the case from gripping the case walls. When I do this, I run moderate loads as bolt thrust increases with an oily chamber.
always check inside the case with a paper clip for head sep too. If forming to Ackley, your case should get slightly shorter which means the brass flowed from the neck area to fill out the chamber. This is what you want because When it flows from the back it can cause head sep. in this case the case length doesn't change or lengthens

 

[FEENIX]

Quality cartridge has discontinued all Ackley improved cases. They will however make a large run if necessary but at $2/ case, they can keep em.

I use to feel that way but with my. 30 Gibbs the prep time saved for COW is worth it.

 

[FEENIX]

As previously noted by most, isolate the brass issue first with new brass. Don't complicate it unnecessarily.

 

[ktaboga]

You noted that the Winchester brass that failed was "old". One other factor might be cold welding of bullet to case. There is a forum here on LRH about 4 years old that discusses that. I saw this about 3 years ago with blown primers in some .243 rounds that my father had reloaded 35 years earlier. When I re-seated the bullets back .005, you could feel the "weld" break in a few rounds. No blown primers after that.

 

[Seabeeken]

You noted that the Winchester brass that failed was "old". One other factor might be cold welding of bullet to case. There is a forum here on LRH about 4 years old that discusses that. I saw this about 3 years ago with blown primers in some .243 rounds that my father had reloaded 35 years earlier. When I re-seated the bullets back .005, you could feel the "weld" break in a few rounds. No blown primers after that.

Bullet weld can be a bear. You can really tell the difference when pulling them. I started using a qtip to apply a thin coat of Lee lube in the neck to prevent it and so far it seems to work well. Also used Redding dry lube too. It also improves ES/SD numbers for me.

 

[watersfam]

You noted that the Winchester brass that failed was "old". One other factor might be cold welding of bullet to case. There is a forum here on LRH about 4 years old that discusses that. I saw this about 3 years ago with blown primers in some .243 rounds that my father had reloaded 35 years earlier. When I re-seated the bullets back .005, you could feel the "weld" break in a few rounds. No blown primers after that.

The Win cartridges that I used were pretty old- probably late 60's stock. I have looked at a number of the photos posted the on head space issue including Hugnot's. There is a noticeable area of stress that looks like a shiny band near head on all. My cartridges that failed also show a shiny band in same area. Again, I am not sure why, but the Silvertips had zero failure. They are probably 1980's to 1990's stock, so they are newer and the bullets are 117 grain and longer than the older 87 grain cartridges.

I just received a couple of boxes of Hornady +P boat tails that I will try this weekend. Will post the results.

 

[watersfam]

So the 40 Hornady +P cartridges fire formed perfectly. A box of 1980's-era Winchester .257 Bob cartridges had all but one form out perfectly. Unfortunately the one I fired off that ruptured, did something to my ejector pin on the bolt (it appears to be stuck in the housing). I also acquired a complete box of .257 AI reload cartridges that had already been formed. The posts that talk about differences in milling chamber shapes were correct. Every one of these stuck in the chamber and had to be popped out with a ramrod. None of them ruptured, but you could tell that the reloaded AI's I shot through my rifle were "pushed up" or formed out a little above where the AI cartridges were before I fired them.

 

[Seabeeken]

Some don't seem to set the barrel back enough. A factory 257 Robert's would make a good headspace gauge during headspacing and set it snug. If it's a profit barrel, loosen it and set it back

 

[arch408]

I have 5 boxes Winchester virgin brass. $100 + shipping.

Do you still have the brass? I'm interested