Home Forums Reloading Big Game Rifles Shoulder measurement variances on .308 Win brass?

would .003-.004" less on shoulder/comparator measurement than, factory ammo be too much slop to fire safely? I'm using hornady case comparator set. All the other rounds loaded are within .001" of the factory Remington Core-Lokts. Thanks! I measured the factory rounds. There is .003" difference between the the the shortest and the longest measurement of the factory rounds. My shortest handload is .002" shorter than shortest factory round. Probably getting confusing sorry lol!

Factory ammo is always going to measure "short". I'd be more concerned about what the measurement is of once fired vs. factory vs. your handloads. With that being said, your handloads probably shouldn't be shorter than the factory ammo. That factory ammo uses virgin brass that is generally SAAMI spec. Your handloads, if you size right, should probably be a hair longer, when measuring with a comparator to the shoulder datum, than factory ammo.

I'll try to get some measurements after firing soon. In the meantime I'll not, fire the rounds in question yet. Thanks for your help!

if your worried about the short ones load a bullet about .010 into the lands and use them as foulers after you clean your barrel, as long as mag box length allows and load isn't loaded hot.

.oo3-4" is not a problem.................unless you have a gun with very long HS, like +.oo7" or more.

BUT, depending on you gun's HS, you do not want to make a practice of sizing brass much more than .oo2-3" less that whatever your fired brass is as stretching more will reduce case life, & in extreme cases, cause head separations.

IIRC, factory brass can go to about -oo4 to assuming SAAMI minimum HS is zero.

But I've seen factory brass as +.oo2-3" as well but pretty unusual.

MM

Thanks a lot for all the good info folks! The rifle is a Weatherby vanguard in .308

The way I read it he's not bumping .003" or .004", he's three or four under factory new. That's a lot of headspace in a typical chamber.

Am I missing something here?

Yes .003-.004" under factory.

That's kind of how I'm reading it too.. Sounds like he's pushing the shoulder back way too much, or maybe not reading the comparator right???

Thats why I said jam them into the lands just like a AI cartridge. I bump my brass .003 from fully formed brass.
I've seen new belted stuff .010 under fully formed brass

The brass that’s .003-.004” under, is it new brass, or fired but not sized, or has it been resized?

Yes, that could be a problem, depending on what the HS on your chamber is.

If it's at SAAMI minimum, probably OK for 1 firing, but surely not for successive firing at that dimension below min.

MM

That's what I don't like about a lot of belted brass.

First of all a dial caliper, which I'm assuming you're using, is not exactly a precision instrument in the wrong hands. 6 people can take readings on the same object and likely give six different measurements. It all depends on how consistent YOU are in using it. Practice on the same piece of brass; slight pressure on the caliper, and twist/wiggle the case a little to make sure it's seated completely at the case head and at the shoulder. Get a feel for getting the same measurement. Just the nature of your question suggests you don't have a lot of experience with using one.

And, why on earth are you not measuring fired cases and using THAT measurement to set up your die and determine a shoulder bump? As stated above factory ammo is loaded into virgin brass and absolutely the worst thing to reference by here.

I've got some fired brass from Remington Core-Lokt 180gr. Factory rounds but, the shoulders haven't changed much at all. All the brass I've been measuring measures the same every time I measure it. I've been measuring with a Mitutoyo digital Caliper which seems to be pretty consistent with its measurements. The way the fired factory cases are measuring now, they should still chamber fine as is with just neck Sizing.

Why are you measuring against loaded factory ammo? Thats totally meaningless. Measure against brass that has been fired in your chamber. Then bump back.

I just started with the new brass as a starting point. I was waiting on primer order. This new brass that I fired five rounds of might have increased .001" in shoulder measurements. 3 cases had no increase so I don't think I want to do any bumping until after 2 or 3 firings as I normally to with my 6.5 Creedmoor after the shoulders streach more. I also measure each fired case 3 or 4 times for consistency. But at this time there is nothing to bump back without going to equal or below the factory round measurements. All five fired rounds still chamber easily. Thanks!

I've seen non belted be as much as .008 short, if you just reduce your load some and fire them you then you will be fine or jam them into the lands not a big deal for me I never do load development on virgin brass anyway. Most AI brass is way shorter to make so if you treat them like that no problem.

New brass never gets the shoulder bumped until 3rd firing to make sure its fully formed unless you want to make a false shoulder which should get it first time.

Yeah, I'm thinking about loading some rounds with the bullets seated about .010" into the lands and see what that does. Thanks!