Gun limiting OAL

[bk09]

Well I have finally got around to load some .257 Roberts for my Kimber Select Grade. The issue comes with the overall length since Kimber in their infinite wisdom bases their .257 off a short action when they are usually long action. I have some 90gr GMX bullets that are recommended to seat at 2.880". After a ton of time reseating to an acceptable OAL I got it to barely fit in the magazine at 2.835". I have some IMR 4350 for it and hodgdon recommends a minimum of 40gr. In the past I have been able to cross reference my Hornady manual which is almost always lower on the starting charge than the Hodgdon website. So what I'm here to ask is... Would you load a bullet that has to seat that much deeper than recommended OAL? Hodgdon has 40gr listed at 39,400 CUP and the max of 44gr at 44,200; a 4800 CUP difference. I would probably try a starting load in the mid 38's to low 39's and check for overpressure. Let me know what you think.

[shooter]

A lot of rifles make you use different lengths to fit there magazines. not a big deal. Ive found that different shapes in the bullets will make some of the same weight different lengths, shouldn't be a problem,

[SemperFiGuy]

bradkoll:

Could be a mis-match between official specifiers  (Hornady and SAAMI).

SAAMI lists the cartridge overall length for .257Roberts (including the hotter +P) as:

2.260 in. minimum
2.780 in. maximum

Of course, SAAMI never indicates which specific bullet they have in mind for their specifications.   Which I've always thought is just a teeny bit odd.

Anyhow, the above dimensions are considerably shorter than the Hornady reloading manual.   If you have some factory loads in the .257Roberts caliber, you might mike them as well for further comparison.

FYI

sfg

[bk09]

Thanks for the input guys, it helps keep my nerves at ease.

[SemperFiGuy]

And--of course--as reliable as the various editions of the Good Ol' Hornady Reloading Manual happen to be, there are the Other RLMs:

Speer
Lyman
Lee
etc.

Which might shed some light on the issue at hand.

Good Luck on your project.   Your self-suggestion about cutting back on the starting loads is always an option.

sfg

[bk09]

I cross referenced the newest hornady manual at work today and it listed the OAL at 2.780, looks like hodgdon has a typo. And hornady starting weight was just over 3 grains less than hodgdon as usual. Looks like I will finally load some rounds this weekend, I need a good reloading session.

[SemperFiGuy]

I cross referenced the newest hornady manual at work today....

Usually a good idea to cross-reference manuals on a new or problematic load.  Often gives a guy some useful information and maybe some helpful insights.

sfg

[noylj]

COL is entirely the reloaders responsibility.
You want to find the distance from the lede/lands/rifling that is most accurate.
The only max COL for a reloader is (1) whatever is needed to fit in the magazine (unless you are not using the magazine and (2) whatever fits YOUR chamber.
The other COL limit is not to go below the manual's COL without reducing the starting load.
For "most" rifles and most "bullets" in "most" chambers, pressure acts opposite to handguns: Bottleneck cases often drop pressure as the bullet is seated deeper (to some limit) and pressure goes up as the bullet approaches the lede/lands/rifling.

[358156hp]

Guilding metal bullets usually have different recommended COL than standard cup & core bullets do. Oftentimes, it can be difficult to get acceptable accuracy from GMX & Barnes X bullets unless you follow the factorys recommended seating distance to the lands. Personally, I'd follow Hornadys data for that specific bullet.