Bullet Seating Depth

I am no expert reloader by any means and I am using a RCBS 5 press along with a Redding bullet seating die that has the micrometer on it. While reloading last night I was measuring the base to ogive and it would vary by as much as .oo5 sometimes. I am reloading for my .260 which I use for hunting mainly out to 200 yards but target shoot for fun out to 500 yards or so.

My question is how much is an acceptable amount of variation in seating depth for you guys who are experienced reloaders?

I look for 0.002" variation generally. The tip of your bullet may be contacting the inside of the seater stem and causing the variation you're seeing.

What brass are you using? If you are using Lapua brass, the necks are VERY tight and thick, which will vary the seating pressure. I always run the brass over an expander ball to loosen up the necks and help with the consistency.

Yes, I was using Lapua brass. Some of the brass was unfired and some of it has been fired once or twice.

Yes, the virgin brass will have firm necks. I don't like loading on virgin brass for the 260 with Lapua brass. I use the expander ball to loosen up the necks. The fired brass will also seat different than the virgin, so you will need to adjust your seating die to get the same seating depth.

How much variance would you typically say is acceptable for a hunting round verses a precision long range shooter?

You should get less than .005" you were seeing. I would think it should stay within .001" to .002". You could also use a mica on a Q tip rubbed on the inside of the case neck. This would help. I used to do this, and it works fine.

JTS, how many times has your brass been fired? Do you anneal?

Some of it is new brass. Some of it this is the second reload.

^^ Virgin and fired will seat differently. I don't like combining virgin with fired at the same time. I keep brass on the same cycles. I generally buy 200-500 pieces of brass, and load them in batches. Do load work up on virgin and shoot all the virgin brass up. Then reload them, and confirm the original load with the fired brass, with maybe a few tenths of a grain less and more to shoot and compare, all while chrongraphing the speeds. Often times the reloads will run slightly hotter than the virgin did, and I need to back the load down .2 grains or so.

If your loading hunting rounds that will be shot inside a couple hundred yards a .005” variance won’t really make a difference in accuracy. It might not make much of a difference out to 600 or 700 yards either. You have to shoot them and find out.

If you want benchrest accuracy, then yeah, it makes a difference. Consistent,precise brass prep is were you should start and that usually yields tighter tolernences for neck tension and seating depth consistency.

There is a easy method to seat bullets with that die that will result in pretty much exact B.T.O. dimensions but it will slow down your work flow.

You will need to re-zero your seating die so that it seats every bullet .006” to .008” long. After you initially seat the bullet you measure the base to ogive again. If it measures .007” long, use the micrometer and turn it down .007” and run the round through the seater again. Measure it again to double check and if it’s good re-zero the seater and go to the next round.

Did I mention that this method slows down the bullet seating process.

I use this method for three rifles. The others I load for get run through the seater just once.

Thank you, I will remember this and try it out sometime.