Ack Bullet Seating Troubles!

[mac86951]

OK, I'm not that new to this, but this one caught me off guard.

Short Version: Bullets seating crooked.
Seating 77gr SMK on 23.4gr Varget (not compressed load).
I've tried several brass batches, Win, Nosler, Hornady, FC, and LC Its not the brass.

Case is concentric as measured with sinclair concentricity gauge.

Sizing Die: RCBS Competition
Seating Dies (note I say plural, they both do it)
RCBS Competition, and RCBS standard die.

Problem: I do all the brass prep, other than turning necks. This is ammo for a gas-gun so I think that is overkill. When I check loaded bullets, I not only have .005" or more run-out, I can visibly see the meplat wobbling. 1 out of approx 7 load without a problem run-out of 0.002. I can't seem to repeat that process. Am I doing something wrong, or is this the bullet? I have tried varying my seating procedure (fast, slow, 90° turns, etc), but I get the same result.

Has anyone had this trouble before, and is there a way to sort bullets ahead of time?

-Mac

 

[jonbearman]

What kind of neck tension do you think you have and I use a vld chamfer tool so the bullets get a square start. Just for grins what press are you using.

 

[mac86951]

Long version of story:

Noticed that accuracy of my rifle was degrading quickly, 223 shouldn't be worn out at 1500 rounds, not with a 77gr at 2.260 with 2650fps and a Wylde chamber. I'm loading up rounds for pressure testing with the same brass lot that performed well not long ago, along with my various primers and current bullets and finally thought to re-check run-out on the loaded rounds. I had though of run-out issues before and switched to the RCBS competition seating die to resolve that issue. To my surprise, there it is again.

I'm guessing I could roll the bullets on the table and see if there is an issue of meplat to bearing surface, but I'd really hate to see that. I could also try sizing brass in my old sizer instead of the RCBS competition sizer, but I'd expect to see the external neck run-out be an issue too.

Thoughts?

 

[mac86951]

What kind of neck tension do you think you have and I use a vld chamfer tool so the bullets get a square start. Just for grins what press are you using.

I'm using an RCBS rockchucker, same press i have for years.

I'm using a Lyman VLD chamfer tool for inside neck. I tried another set of 50 with the standard 45° too, same results.

-Mac

I'll measure neck tension now.

 

[mac86951]

Neck Tension is .004-.005"

Lucky me, I loaded the first 50% of a win brass before I saw the problem, the remaining is ready to load...

-Mac

 

[fredhorace77]

a couple things that came to my mind, may not help but worth a look into. how do u clean ur brass? wet tumbling sometimes makes it too clean and makes seating harder. are the insides of the necks clean, carbon build up could be causing excessive neck tension. too much neck tension might be a problem also. maybe try a busing die with .002"-.003" neck tension. could it also be ur setting stem is not contacting the bullet square and solid? try removing ur seating stem and visualy check to see how well the bullet lays into it. maybe try annealing ur necks also. may also try a different shell holder maybe the current one is not square to the die. just for kicks try lubing ur bullet and the inside of the neck then seat one and see if it corrects it. if so its probably too much neck tension.

 

[Joe R]

fredhorace77 said:
too much neck tension might be a problem also.

I believe the general rule is .001 neck tension for bolt guns and .003 for gas guns, so .005 tension may not be helping things.

Are you annealing the brass? Annealing makes the brass "grabby" and more difficult to seat.

 

[mac86951]

Thanks all, no annealing yet, brass fired 3 times. I've had good loads with this before and I think I found the issue. The problem seems to have been reduced by a good cleaning of the press ram and reoiling and an oring on the die between press and lock ring. Guess something is out of whack there. After doing both, now I'm back to 2-4 thou which is what I expect. 2 thou for score 4 for practice.

I must have had the lock ring too close to the window or something on this setup. Maybe that would cause a distortion.

 

[mac86951]

a couple things that came to my mind, may not help but worth a look into. how do u clean ur brass? wet tumbling sometimes makes it too clean and makes seating harder. are the insides of the necks clean, carbon build up could be causing excessive neck tension. too much neck tension might be a problem also. maybe try a busing die with .002"-.003" neck tension. could it also be ur setting stem is not contacting the bullet square and solid? try removing ur seating stem and visualy check to see how well the bullet lays into it. maybe try annealing ur necks also. may also try a different shell holder maybe the current one is not square to the die. just for kicks try lubing ur bullet and the inside of the neck then seat one and see if it corrects it. if so its probably too much neck tension.

Thanks I'll see about neck tension changes between my two sizing dies.to see how that goes. Might need to fess up and go redding or Forster on the seating die. I'll wait for results in case I need a set.