Help me figure out what is going on here

[7magsavage]

Ok, been loading for a couple of years. Loaded many rounds for my 7mmRM that I use in competition as well as hunting. Never had this problem before:

I loaded 60 rounds two nights ago for a competition that's coming up next month. All was well.

I start loading tonight and I am having a big variation in my OAL (measured from the ogive with my bullet comparator in calipers.)
I loaded 30 rounds that had a spread of 0.0010" between that lot. I quit loading until I figure out the problem.
They are Bergers, from a 500ct box that I have used probably 2/3 of. Never had an issue.

I thought it may be dirt on the shellholder. Nope.

I thought it may be dirt in the comparator. Nope.

Thought it may be batteries in the calipers. Nope.

I rechecked the lengths of the rounds loaded two night ago and they are dead-nuts on the money (maybe .0001" variation).

What gives? The die has not been touched in two days. Nothing has changed.

Any help that anyone may think of that I haven't yet would be greatly appreciated.

Steve

 

[roggom]

Re: Help me figure out what is going on here

Have you checked the bolts in your press arm? The Lateral movements can cause seating variation.

 

[7magsavage]

Re: Help me figure out what is going on here

I checked. Not a bad idea, but there are bolts that are in position with clips instead of nuts. The movement couldn't have changed.

 

[nso123]

Re: Help me figure out what is going on here

One thing that I have noticed that can impact OAL, particularly if loading with a powder that fills the case pretty full, is the way the powder is sitting in the case. It can sometimes cause the bullets to seat differently from one to the next. Could this be the case with your loads?

 

[7magsavage]

Re: Help me figure out what is going on here

Well, I don't think so, because the load been the same for over a year now and I have never had the issue before.

 

[Rookie]

Re: Help me figure out what is going on here

So you loaded 30 rounds and had a total variance of 1/1000 of an inch in OAL? Try loading some SMKs where you will have easily 10X that much variance. Seriously dont sweat it. What kind of match are you shooting? Benchrest?

 

[427Cobra]

Re: Help me figure out what is going on here

Did you size all your brass then loaded some, a couple days later tried to load some more and the problem showed up, if so the springiness of the brass is the cause, resized the brass again.

 

[insight3b]

Re: Help me figure out what is going on here

Probably didn't remove the slop from the threads when setting up the die. Back out your seating stem 3 full turns...loosen the lock ring. Seat a bullet and tighten the lock ring. Return seating stem to desired and crank em out

 

[7magsavage]

Re: Help me figure out what is going on here

I'm sorry. I got zero happy. I meant I had a variance of ten one thousandths.

 

[jfseaman]

Re: Help me figure out what is going on here

If using digital calipers, change the battery.

If using dial, never mind.

 

[7magsavage]

Re: Help me figure out what is going on here

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rookie</div><div class="ubbcode-body">So you loaded 30 rounds and had a total variance of 1/1000 of an inch in OAL? Try loading some SMKs where you will have easily 10X that much variance. Seriously dont sweat it. What kind of match are you shooting? Benchrest? </div></div>

I meant ten thousandths not .001 as I said. Sorry about that one. I am shooting the Mammoth Sniper Challenge Jan 4-6th.

I used to shoot SMKs when I first got the rig put together. They shot good, but I couldn't deny the ballistic advantage of the Bergers even though they are a bit of a pain to find the sweet spot. My sweet spot just happened to be slightly in the lands.


But I think I found the problem. I took the seater die apart (Forster benchrest) and it was dirtier than I would have thought. I sprayed that sucker down with carburetor cleaner and the variance tightened up considerably.