Reloading allowable variances...

[Duke878]

okay I'm reloading .308 on my lee Single stage press. I've only done about 150 rounds so I'm still quite new. I'm curious to how much variation from the specs are tolerable and safe. For example:

-case length calls for 2.005". Some end up 2.003-2.007.
- the recipe book calls for 43 gr of powder. I get between 42.9-43.4
- OAL of finished round calls for 2.735". I get between 2.73-2.74"

Also what's the shortest OAL i can go in an M14? When setting up my die, the first few came out between 2.675 and 2.701 (books says 2.735) are these few rounds safe to blast off?

Thanks!

 

[hk33ka1]

Assuming that powder charge is below max in your manual it all appears good to me for your M14. With match quality ammo for more precise rifles you will want the charge the same +- .1 gr but for this rifle your variance will be fine. You won't get the bullets to seat to the exact same length because they are not seated by the tip where you are measuring but a little further down the bullet where the cone shaped seating stem in the die touchs them. Not all bullets are the exact same shape in this part (ogive) so the OAL of rounds will be different. This is perfectly fine. No need to change the die for every round.

 

[9.3mauser]

You're over-thinking this. Max. case length for the .308 is 2.015; as long as you're not over that, don't sweat it. Once you go over it's time to trim to 2.005. There will be a noticeable velocity difference with your powder charges. I prefer to keep mine as consistant as possible, but as long as you're not over maximum, again, don't sweat it. As long as your ammo functions properly in your rifle, I wouldn't worry about it.

That said, it is good practice to be as consistant as possible in your loading. It'll just make you a better handloader.

 

[ATOM]

In general, I'm with hk33ka1 and 9.3mauser. Unless you are shooting match, minor variations are not worth worrying about. Provided that you are not over the max propellent limit and are not showing signs of high pressure (check your reloading manual for those) and provided that what you are reloading feeds, chambers, fires and extracts OK, I wouldn't worry.

That said, most of your variations are minor, but your charge weights have a half-grain fluctuation. That's not too good, actually. You didn't say what powder you are loading, so I can't comment specifically, but if you are assembling near-top-end loads, that kind of uncertainty can put some rounds over the red line. If you are measuring with a charge thrower, stay short of the book maximum to avoid this. One way around it is to throw low and then use a powder trickler to bring it up to the right weight. That of course slows down your production, but if you are after accuracy or if you are near the max charge, then you might want to consider it.

 

[hometownhero]

I have found that in the larger rifle cases like say .308 and .30-06 the .3 of a grain doesnt make much difference for most people where as in something small like say .17AI, .204, or .223 .3 of a grain will make a difference

 

[paperslayer]

What is safe is Something below when you start to see warning signs of excessive pressure such as sticky bolt lift, cratered or flattened primers or hard extractions, or if you start to pierce primers you are way into red line.

For precision, you want to minimize variance between cartridges, and you should get in the habit of weighing each charge. The further you shoot, the more the variables will show up. The smaller the case, the more those variables show up too. Personally, I try and keep them within a tenth of a grain - always.

As to lengths, too long is when the bullet falls out and too short is when the bullet falls into the case. Make them fit you magazine and then fine tune for seating depth using accuracy as the guide. That is all part of your load development process.

COAL variation is inevitable, since the seating stem pushes on the rounded part of the bullet not the tip. Every hollow point bullet has variation in length which is why you should use a comparator for measuring, not tip to tail measurements.