Need Some Help on Inconsistant COL Bullet Seating

S

Stealth1959

New member
Cartridge: 30 Rem AR
Dies: RCBS Small base dies
Bullet: 125 Grain Nosler Bal Tip
Press: RockChucker
Powder: 37 grs Benchmark
Problem: COL ranges from 2.233 - 2.244

I have always loaded for a bolt action with Lee Collet dies so this is new territory for me.

My brass prep procedure is to clean the brass one by one with Ballistol, spray case with RCBS Case Slick, lightly lube the inside neck with a Q-Tip with case Slick, use the die, trim case, debur and chamfer case mouth, prime case, charge with powder, then seat the bullet.

The only thing different is that I moved my reloading operation inside the house and am not using my old :[beeep] for stout" bench anymore. Any idea as to what might be happening? I measured some of the bullets and they are not really consistant in length. The 100 yard groups are 1.0" for 6 shots. The 200 yard groups are 3"+. Thanks in advance for any help!
 
Originally Posted By: hm1996All bullets vary in OAL. If you are measuring the COL from case head to bullet tip it will reflect the difference in bullet OAL.

Using a bullet comparator will result in the only measurement that can affect accuracy and is explained here:

http://www.6mmbr.com/catalog/item/1433308/977259.htm

Regards,
hm

And even when you measure with a comparator don't expect them to be the same.

DAB
 
I've known for a long time now that to get consistancy you need to measure from the ogive...but i always load for max magazine length.....so you have to measure from bullet tip to base in that case...right????? mine always vary in the thousands, but always produce good groups...guess it just depends what passifies you.....
 
Originally Posted By: DABAnd even when you measure with a comparator don't expect them to be the same.

But OP is talking .011" variation. 99% of my loads measure within .001" to a maximum variation of .002" measured w/the comparator. I'm sure the fluctuation is much greater than that were I to bother to measure tip of bullet to head of case.

Originally Posted By: shanedoggI've known for a long time now that to get consistancy you need to measure from the ogive...but i always load for max magazine length.....so you have to measure from bullet tip to base in that case...right?????

Yes, to determine length of magazine, but your seating die does not contact the bullet at the tip; it contacts bullet somewhere near the diameter of your bore, therefore, if measured w/comparator you will find your loaded rounds to have much less fluctuation in the length.

It would surprise me if the OP would be getting 100 yd moa accuracy if the length of his loads varied .011" measured w/a comparator.

Regards,
hm


 
I have found if you measure each bullet/projectile with a comparator before you seat them and put them in lots of like length this helps a lot in col measurement. I have used this method for years when I am trying to get the last bit of accuracy out of a load.

You will be surprised at the variation in bullet length even in some of the high-end bullets.

jme
 
I got the Hornady Bullet Comparator and measured off the ogive. The loaded rounds only vary .001 now.

Primers are seated correctly and I think I'm good to go. Thanks guys!
 
Originally Posted By: arky65I have found if you measure each bullet/projectile with a comparator before you seat them and put them in lots of like length this helps a lot in col measurement. I have used this method for years when I am trying to get the last bit of accuracy out of a load.

You will be surprised at the variation in bullet length even in some of the high-end bullets.

jme

Maybe I'm missing something here, but, assuming the seating punch being used is the correct one, I fail to see how this will result in any improvement in the loads. Unless a flat point bullet punch is used on a spire point bullet (an intentional exageration for purpose of illustrating my point), the seating punch will contact the bullet being seated at the same diameter of the bullet each time, resulting in essentially the same OAL from one cartridge to the next (when measured with a bullet comparator) irrespective of a small difference from one bullet to the next.

OAL is, after all, nothing more than a measurement and the comparator is taking that measurement at the exact location on the bullet that actually has an impact upon accuracy.

Accuracy is not affected at all by the relationship to the location of the bullet base or tip to the beginning of the rifling. IMHO, round to round consistency of the "bullet jump" is the important factor and that is controlled by distance of the ogive from the start of the barrel lands as explained in the link posted above.

Quote:For max accuracy you need consistent bullet position relative to the start of the barrel's rifling. You can set this by trial and error, but it is much easier (and more repeatable) to use the Hornady O.A.L. Gauge to measure case length with the bullet ogive just touching the lands. When combined with a Bullet Comparator (with caliber-specific insert), you can also very quickly measure case base to ogive for any loaded round.

Regards,
hm
 
Originally Posted By: arky65I have found if you measure each bullet/projectile with a comparator before you seat them and put them in lots of like length this helps a lot in col measurement. I have used this method for years when I am trying to get the last bit of accuracy out of a load.

You will be surprised at the variation in bullet length even in some of the high-end bullets.

jme

Why not measure and sort after loading, should give the same result ?
 
Originally Posted By: hm1996
Accuracy is not affected at all by the relationship to the location of the bullet base or tip to the beginning of the rifling. IMHO, round to round consistency of the "bullet jump" is the important factor and that is controlled by distance of the ogive from the start of the barrel lands as explained in the link posted above.
hm

Agreed .
 
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