Bullet manufacturing tolerances

[charadam]

I am reloading for maximum accuracy in a few calibres and have been considering meplat uniforming as my next step.

The internet is full of advice on this - and mostly it is stated that this is a useful long-range technique with no pay-off for under,say) 400 yards.

However, I measured a batch of bullets the other day and found .012" maximum variation in length.

I seat bullets for .005" to .015" jump measured on the ogive - but I check COL from case rim to bullet tip. Obviously this gives up to .012" variation with these bullets.

Wouldn't you know it - the "long" rounds wont fit the magazine!

So I suppose meplat uniforming is necessary - what's the best tool?

Thanks, Charles

 

[Cheechako]

Charles

Are you measuring bullet OAL or length from base to a point on the ogive? .012" is an awful lot of variance for match grade bullets and I doubt if most custom bullet makers would tolerate that much.

And BTW, not ALL long range shooters feel that meplat uniforming is worth the time. Me, fer instance.

Ray

 

[charadam]

Ray,

Bullet OAL - the batch with the .012" variance was of 140gr 6.5mm HPBT.

Of the 200 bullets measured, approximately 20% were .009" to .012" longer than the minimum. 11 bullets were .012" long.

About 75% were up to .003" long with the remaining 5% not more than .005" long.

Surprised me I confess, however I have found a few references to others experience of the same thing.

All the best,

Charles

 

[Cheechako]

Charles

OK, that much variation in bullet OAL is to be expected in HP bullets. If your seating die makes contact on the ogive,which it should) the cartridge OAL will vary by the same amount but the amount your bullet is off or into the lands will be consistent.

It is the fashion nowadays to uniform the meplat with the goal of increased accuracy but the jury is still out on that one, IMHO. Many shooters have reported the desired improvement while others have reported no change. Another procedure tried is to measure and sort bullets by OAL but, again, the results are mixed.

I usually say that if you do something that makes you FEEL like you are improving things then by all means do it. Confidence in your equipment is a big part of winning. On the other hand, there are so many environmental factors that affect your group sizes at long range,600 to 1000 yards) that I feel the time you spend on such things is probably better spent in practicing.

But again, just the opinion of one po farm boy.

Ray