Two questions..

InTheWeeds

InTheWeeds

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Minuteman
Oct 21, 2008
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Somewhere in da weeds of TX
www.fotographi-rossi.com
#1
1. What is this doing to my accuracy? Apparently five reloads is the max on new Lapua brass before needing annealing, and seeing as how I still have about 40 rounds of loaded ammo on this same lot of brass, I figure I will just shoot them.
2. What kind of damage is this doing to my chamber? Superheated gasses going where they are not suppose to doesnt really make me feel comfortable.
I had no idea this happened while I was shooting, so I feel there is no need to panic for my safety. I was shooting Larue auto targets from 500-750 when these happened in variable 10-15 mph wind, so I really have no idea if accuracy was affected or if the wind was just toying with me.
IMG00009-20110217-0250.jpg
 
#2
Re: Two questions..

Not the best for accuracy. Your neck tension will not be consistent and besides that you have perfectly good brass going to crap!

It shouldnt be doing much damage to your chamber so I would not stress. If its just brass that is work hardened, then its just the brass that is damaged.

I would not expect Lapua brass to split after 5 firings... I would look into annealing.

Also, check the diameter of your necks after they have been fired. I wonder if your chamber is a bit large in the neck area and the brass is expanding outward more than it should.

I now include annealing after every firing. The max I will let the necks go is about 3 firings, but that was in the past... I feel annealing aids in accuracy when done properly.
 
#5
Re: Two questions..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: In da weeds</div><div class="ubbcode-body">I had no idea this happened while I was shooting, </div></div>

You could not stop and look at the cases while shooting?

In any event, I got 26 reload cycles from a lot (100) of Win brass Neck Only sizing (Body size when needed) with a stiff 47.8 gr Varget and 155 scenar loading befor I lost a case (body crack). I lost 6 cases on reload cycle 26; 2 Insipient case head separation, 4 body cracks. And these cases were never annealed.

The above was done with a Remmy with a standard wide diameter and long throated Remmy barrel.

So, when a case comes out of your gun, what is the obturated neck diameter?
And when you have seated a bullet and its ready to fire, what is the seated neck diameter?
Finally, can we see the base of the case to judge the diameter of the chamber itself?
 
#6
Re: Two questions..

+1 Mitch

Somewhere along the line that brass is getting worked hard. Either your resizing die is really working the necks / is pushing the shoulder back way too much or your seating die is really tight.

Take any survivors and remeasure the brass that comes out in comparison to what it comes out of your press at. That may tell the tail.

Cheers,

Doc
 
#8
Re: Two questions..

Some clarification- when I said I didnt notice anything while I was shooting, I meant there was no noticeable difference in recoil, sound, smoke, etc while the round was being fired. After ejected was when I noticed it.
These rounds have about 3 reloads going through a RCBS FL sizer die before I switched over to a Forster neck bushing die. Right now I am using a .334" bushing (for .308 BTW), and the necks were turned to .012" thickness before the last reloading. Very rarely do I have any tension when running this brass through a .334" bushing, so my guess is my chamber is tight. Its a bone stock AR30.
I switched to the Forster die after I had a few other necks split only slighty (barely enough to see with the naked eye), but I have never seen anything like this before.
The load data on these was 42.0grs IMR 4895 at 2570fps with 175 SMKs.
 
#9
Re: Two questions..

Mmmmm cant say I know too much about neck sizing as I avoid it, But i would have a good look at what happens to case necks after firing... measure them up and then measure when you size them.

Ask around as to what others are getting as a fired neck diameter.

I have the feeling your necks are being overworked alot at some point, hence the premature splitting.

Are the cases nice and lubed when you size them?
 
#12
Re: Two questions..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: In da weeds</div><div class="ubbcode-body">the necks were turned to .012" thickness before the last reloading. </div></div>
Problem solved.

1- .012" is too thin.
2- why neck turn in a 308 using Lapua brass. Doesn't make sense to me.

Just load and shoot the round. I've seen more people create their own problems by trying to get all fancy with their reloading techniques, and end up having issues. I will bet you money that you could not tell the difference on the target with a 308 from regular FL sized prepped Lapua brass, than all tricked out, neck turned, fancy pancy prepped brass. A good load with standard prep can/will shoot very well. After all- it's just a 308 in a bone stock AR30.
 
#14
Re: Two questions..

If you are not neck turning for a tight neck application just clean them up. Take off enough to clean them up .001-.0015 is enough. Whether it has a place or not depends on who you ask. Cleaned up necks and standardized neck tension are part of my precision loads. I do not waste the time unless it is a precision application.
 
#15
Re: Two questions..

As 427Cobra is pointing out, If your factory chamber is as tight as possible and still meets sloppy SAAMI specs, and you poke pin gauges into your chamber neck, the .344" will probably go and the .345" will probably no go.

That is not Lapua's fault.
 
#16
Re: Two questions..

Im cutting the necks down to .012" because thats about where it needs to be to have evenly concentric necks. I have noticed about a 10-15 fps closure in my ES from doing this as well.
I'm heading out to the range tomorrow to pop off a few rounds so I can measure the fire-formed neck thickness. In the likely event my chamber is too wide, would the remedy have to be a whole new action or is it possible to put an insert in the chamber and ream it to within spec? Or should I just buy an annealing machine and anneal after 3 or 4 reloads?
 
#18
Re: Two questions..

I couldnt tell you if thats a lot of expansion as im just not sure on the figures myself... perhaps someone that neck sizes can chime in
smile.gif


In regards to your prior comment, the chamber itself is within the barrel so IF your chamber was up shit creek, worst case scenario is a new barrel... I doubt this is the case as it would imply a buggered reamer, but who knows. Im not a smith so I dont see these things, and maybe a rifle with those specs are good to go, because once fired brass wont break.

Annealing will deffinately help. Try annealing new brass without turning the necks... also do some load development after the 2nd firing. You might find this solves the problem with the necks and brings your ES/SD back within excellent limits.
 
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