Home Forums Hunting & Shooting Ask The Gunwriters .257 Ackley Chamber or Die Issues

I have a new-to-me .257AI. I fireformed two boxes of Remington factory .257R ammo through the rifle and have a couple of issues that have me puzzled. Incidentally, the factory ammo fit very snuggly in the chamber, so there wasn't any movement during firing.

1) Using a Hornady Case Gage, I have a .010" spread in the length of the fired cases from shortest to longest, which is larger than I expected. This is the first cartridge that I have actually used the Hornady gage on. Is it typical to see this kind of variance in case length? If not what could have caused the runout?

2) I have a set of new Lee Pacesetter dies that came with the rifle. I set up and sized some of the brass and even with as many as three turns past contact with the shell holder, I am getting only about .0015" bump in the shoulder of the longest cases. I'm going to contact Lee, but does it sound like I have a faulty die or is something else amiss that I haven't thought of?

I appreciate any thoughts or ideas anyone might have.

Do your fired cases rechamber easily, and I would bet that they do, if so buy a collet neck die and just use that
The beauty of AIs is the reloading process is so easy

And throw the case gauge in the back of a drawer somewhere

When you mention the variations in "length of the fired cases" with the Hornady Case Gauge, it sounds like you mean head-to-shoulder length, not overall case length. Is that correct?

"Only" .0015 inch bump of the shoulder is common with many FL dies--especially in improved cases, because so many chambers vary somewhat in headspace.

The best rule is to have unfired factory cases chamber slightly harder, due to the slight radius on the shoulder/neck. This prevents the case from being driven into the chamber very far from the impact of the firing pin, so fire-formed cases end up firmly headspacing on the shoulder.

This may not seem to be a big deal, but have seen .257 AI rifles with chambers set up correctly for this engagement of the new-brass shoulder/neck radius fail to fire around 1/3 of the time when using previously-fired brass. This is because the fired brass lacks that little radius.

It sounds like your cases aren't fully formed yet. It may take 2 or 3 or more firings to fully fill out the shoulders & the headspace depending on the brass & your loads. Did the unsized fired cases chamber hard? Dont bump shoulders until the brass gets hard to chamber. Then slowly turn the die in until the bolt closes easy.

Did you remove the spent primers before measuring? On firing the primers back out a bit & can add a few thou.

This is a personal thing but I wouldn't use a Lee die unless there was absolutely nothing else available. Maybe they've improved in the last 30 years. Try the above first. Everything may resolve itself & your dies may work splendidly.

The variation in the length of the cases is due to variations in pressure and, possibly, brass hardness, from cartridge to cartridge. It doesn't help that the factory 257 Roberts loadings are often very mild. In theory, you just have to fire your factory case and then reload your perfectly formed AI case but this isn't always the way it works; except with the rimmed cartridges. Rimless cartridges often tend to shorten up so that the fire-formed case may be short in the headspace dimension. By the way, you don't need to bump the shoulder unless the cases chamber snugly. GD

Have you tried to chamber any of your brass?

Would also add to greydog's post that Remington .257 Roberts brass has varied considerably in every way possible in the last decade, whether dimensionally or in brass hardness. Plus, Remington factory .257 ammo tends to be really wimpy, which would of course add to to the possible error.

All of which would mean that using the Hornady tool ain't much use in this situation.

John,

You're correct. It is the head-to-shoulder length I was referring to. The factory rounds did chamber very snuggly, so I was confident that there wasn't forward movement during firing. The factory rounds were 20 years old, so I was hoping the brass might be a little more consistent than more recent batches.

Thanks for the additional info.

In my experience the Remington 257 brass back then was more consistent--but as noted, the pressure of factory loads was so low that there probably would be variations in case expansion, particularly since firing them in an AI chamber would reduce pressure.

From working with that round in a few rifles, I'd add this to John's advice:

-Make sure you remove the fired primers when using the Hornady tool. Leaving fired primers in place skews the measurements a few thou.

-Don't worry too much about the measurements until you fire them 2-3 times with a stout load. The light loads that factory ammo has won't blow the case out enough to fully form to the chamber.

-Run....don't walk...away from the Lee dies. The Redding #80322 and RCBS are both great dies for this chamber. If you go with Redding, opting the carbide expander ball # 48256 is worth the extra in terms of not having to inside lube the necks.

Hope this helps. -Al