I have been doing load development with the 185 Berger long range bt and I'm getting excessive run out. I'm using virgin lapua brass and a forester seater. I have loaded 155 scenars with the same setup and have a few stray bad ones. Not the case today, almost every round was between .004-.005". Could it be due to the profile of the bullet and or the fact that I'm not using a VLD stem? I have no clue what could be causing it otherwise. My best group was right at .5 moa at 100 but I feel like with straight bullets it could be better.
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excessive runout...unsure where its coming from
- Thread starter midmoguy
- Start date
What kind of press are you using? Seating "stem" could be an issue. Most times I had issues the cause was powder or crap in the shell holder with my RCBS. Bonanza pretty much eliminated that.
I have a rock chucker II, but that's what i've loaded straight ammo on as well. I will check the shell holder and pull apart the die to check for obstructions. I am going to borrow a friends redding seater to see what happens as well.
Sometimes Ill get a round that wont correct with my Hornady concentricity tool, so Ill pull the bullet and totally seat it again, so far it's always worked out that the runout is then next to nothing and I shrug my shoulders and move on.
Check the runout of your case necks prior to seating the bullet. If they are out of whack the issue could be your resizing process. When my bullet runout gets excessive I usually find the resizing step to be the culprit. Expander balls are notorious for tweaking case necks. If its a bushing setup, maybe it is gunked up with case lube.
Fwiw, i have found bad die locknuts and thread clearances cause the bulk of my runout. I always run the ram up and check clearances between the shellholder and die (assuming things are machined perpendicular). My redding fl sizer is off a few thou.
I have o-rings under some of my dies and that helps.
Also, i use SS media and this flares the case mouth open which will affect runout if using a bushing die as the brass doesn't enter the bushing correctly. When i have to use a bushing die, i always use lee collet first, this helps tremendously although not as straight as just using lee.
I am using non-vld stem from redding, no problems with that or any other bullet. As mentioned, check brass prior to seating.
I have o-rings under some of my dies and that helps.
Also, i use SS media and this flares the case mouth open which will affect runout if using a bushing die as the brass doesn't enter the bushing correctly. When i have to use a bushing die, i always use lee collet first, this helps tremendously although not as straight as just using lee.
I am using non-vld stem from redding, no problems with that or any other bullet. As mentioned, check brass prior to seating.
Checked 200 new Lapua 260 Rem cases and found as much as 0.002" variation in neck wall thickness. Ended up turning the necks and get 0.001" runout or less with 107 SMK.
OFG
All of my Hornady 6 Creed brass has less than .001" neck wall thickness from one side to the other and every once in awhile Ill get a round that has almost .004" runout, and I turn the brass while Im seating the bullets, Ive got the VLD seater, use bushing dies, never use the expander mandrel, once I get that Competition seater die back from Tubb Ill be able to see if the modified 308 seater plug alleviates any and all runout since it contacts the bullet closer to the ogive.
Bingo. I've found that neck turning (in conjunction with o-ringed seaters) nets very little if any runout. Light neck tension also makes for straighter loads, or at least they seem to be more forgiving.
