308 Overall Length issue, not consistent bullet seating

[powerman]

I have an in consistency problem reloading 308, Cartridge overall length varies by 20-30 thousands.
No matter how consistent I move to the stop I get a variation from one to the next.
All parts of the press seam tight (linkage).
The dies are tight, locking nuts secured etc.

I think I have an issue with the RCBS Bullet seat die.
The one I have has a tapered cone so that it hits the bullet on its side and not at the tip.
So the shape of the bullets must vary slightly causing this?
I’m use to Lee which is more flat so hit hits the tip.

Specifics:
Mil brass, 147 grain mill fmjBT mill bullets, pulled
RCBS die set 15501and Lee classic press

Any suggestions?

Thanks

 

[Warm_Garand]

Measure your seating depth with a bullet comparator (from the ogive) instead of the tip of the bullet (which varies, even in say an average Sierra Match King).

You'll probably find that they are seating perfectly consistently.

http://www.midwayusa.com/product/23...ad-bullet-comparator-basic-set-with-6-inserts

 

[Gadsden]

I've had the same issue on a Dillon press/Dillon dies with both .223 and .308. The brass was all trimmed perfectly, but I would get variance n OAL.. after measuring the (mil-surp) bullets, it seemed they were all slightly different lengths so I chalked it up to the bullets.

 

[EddieCoyle]

It's probably the bullets. Who knows how many lots they were pulled from.

 

[LittleCalm]

And seat via ogive with a die like the Forster micrometer seating die. Then you can better seat by means of the distance from the ogive to the lands and not worry about COAL. As noted above, you'll want to get a ogive distance measuring device, like the bullet comparator.

 

[powerman]

Yep it’s the bullets.
The RCBS bullet seat hits about half way down the ogive.
I took the die apart and measured a few from the end of the bullet seat to the cannelure (spelling?) and had variances in length which was a little less than variances in OAL . So the bullets are a little different shape from each other. They all measure 309 just below the cannelure though.
I guess I'll run them so the average is the length I’m looking for.

I don’t know what you mean bullet comparator and how that helps. Isn’t the RCBS bullet seat die doing this?

 

[powerman]

After inspecting the bullets closer, there are 4 different versions, so close but minor differences.
probably different manufactures or lots.

I guess thats what you can get with surplus.

 

[Warm_Garand]

Fixed link to Hornady Comparator in my original response.

Here is is again:

http://www.midwayusa.com/product/23...ad-bullet-comparator-basic-set-with-6-inserts

 

[55_grain]

If you think the bullet is being grabbed off-center by the one side of the seater plug, you can get it half-seated, lift the handle a little to allow the plug to re-center, then seat to the final depth.

 

[powerman]

warm_garand , i happened to be in cabelas and picked up the Hornady Comparator, should help me sort them, thanks

good idea 55-grain on doing a patial seat to recenter seat plug. i know some of my lee dies swival. The RCBS die is solidly connected though

I went to sort projectiles using a cheap digital scale, seams it has 1 percent resolution, they either measure 146.7 or148.1 grain and nothing else.
now i need to find a good digital scale