Bullet seating and measuring OAL

[bsekf]

I am using a Forster BR seating die and measuring with a Stony Point comparator. Trying to seat at .001 intervals for ladder testing of seating depth. I can't get things adjusted so the seating depth is uniform. I get +/- .001 variation in OAL. Is it possible the bullets vary or is it my scale or is .001 too fine? Any ideas? What are your experiences?

Bill

 

[billmo]

Bullet ogives do vary within certain lots. Some more than others. .001 is a tiny amount to work with. My thoughts are if you want to measure settings of that degree of variation, you would probably just need to use a micrometer top "style" die. I use those and pay attention "only to that one tool" for the measurement. I think that would be your best and easiest method and tool to work with. I hope this helps. Bill

 

[rayjay]

I have found it helps to 'double bump' when seating bullets. Run the case and bullet all the way up into the die, come back down a 1/4" or so and then run it up in there again.

 

[spclark]

I do the 2-step too, with a twist to the round being seated between strokes.

I don't think trying to seat every round to exactly the same .001" is worthwhile, or too good for your sanity, either.

 

[bsekf]

Thanks, I guess I am trying too hard. When you fiddle with seating depth, what variation do you use, .01 rather than .001?

Talk about sanity, qualifying cases is bad enough, I'd go more nuts trying to measure bullets. I am indexing so do not give the case a twist while seating but really don't see what it would hurt.

Bill

 

[spclark]

I don't shoot BR; rather use a sling, on a pad on the ground. Irons too, mostly. So I feel confident with ammo that's seated to my current preference for in/out/on the lands, maybe + or - .002-3". Doesn't seem to affect my accuracy any, I can't hold better than maybe 1/2 MOA on a good day. This is for 1000 yards.

I DO pay attention to neck tension,try to keep it around .0010 - .0015) and neck run-out,select loaded rounds for .001" or less for 1K, over that gets relegated for 800 - 900 for Palma, or fouler/sighters.

You can be as anal as your patience,or billfold) allows when it comes to numerical tolerances. Once you stop seeing the effect of your efforts to reduce them to a minimum, you need go no further.

 

[tenring]

First, accurate seating depth is near impossible if you like compressed loads - powder pressure on bullet base destroys uniform OAL. I have both Wilson and Redding competition dies in several calibers. Without the micrometer top, the Wilson seater does not produce uniform lengths - but IBS and NBRSA competitors keep winning with Wilson. I prefer the Redding seater. I try to stay .001 - .003" below my target depth, measured with Davidson ogive tools on my caliper. Each round is placed in a loading tray according to the thousandths it is long. Then its simple to bump the micrometer stem down a thou at a time to uniform them to the preferred OAL.

 

[jb1000br]

For an OAL ladder,to pick your initial depth) I use 5-thou increments and at this point have started basing measurements off of JAM length.

"JAM length" being: the longest you can seat a bullet without it being seated deeper upon chambering.

This is a more accurate dimension to measure then land origin IMO. I do not usually seat within a few thou of where I think the lands start. A gray-area IMO. I start at or a little short of JAM and seat the bullet deeper in the case.

Usually JAM is around 25-35thou in the lands.

Then to chase the lands, as in, a follow-up OAL ladder after a few hundred rounds to check erosion/accuracy, I do 2-3 thou increments.

Using NECO dry-moly neck lube my,BR) rounds are all +- 0.001 OAL base-to-ogive

HTH,
JB

 

[itfliesitdies]

I agree with the .005 increments in depth. If you wish to go more detailed, wait until you run the ladder at .005 increments and get a close optimal depth,and then try it in .002-.003 increments once youve narrowed down the field. I start about .030 off the lands and go up to about .030 into the lands. I have found if you sort your bullets properly, the seating depths will remain fairly accurate if you use a quality seater die. For the price, I have had good luck with forster products but Redding is also great! I