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308, five Shots, 2 Groups?????

 
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Old 05-20-2013, 08:19 PM
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308, five Shots, 2 Groups?????

Guys, I have a very accurate 700 VSSF, in 308. My load is 42.2-8208-168' or 175 SMK. Up until very recently, five shots went into a hole that most of the time, you could maybe see two distinct holes.
What is going on now, is first shot, on the money, second shot, a half inch away, third and forth shoot, in the first hole, and the fifth goes to where the " flyer " went.
Essentially, forming two groups. This has started all of a sudden, and I don't know why. I have heard of it, but have never had to deal with it myself.
My brass, is Remington, which for some read on, this gun loves it. It has about 6-7 firings on it, and I try to keep it rotated, and to keep track of how many times it has been fired. Torque on action screws is at 40 inch / lbs. Rings and bases tight, scope is tried and true! I did JUST get into a new can of 8208, but this was happening before the end of the first pound! Any thoughts from some of you 308 Gurus ?
I also have, Varget, 4064' and RL15. I have BR2, 200, 210's, and WLR primers.
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Old 05-20-2013, 08:24 PM
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Re: 308, five Shots, 2 Groups?????

How often do you anneal the case necks ? Have you bedded the action ? The multi group scenario is not unusual for a factory stock. Unless you did a bunch of work to it, maybe you have been lucky ? How many rounds down the tube ? Perhaps the throat is starting to go ?
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Old 05-20-2013, 08:33 PM
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Re: 308, five Shots, 2 Groups?????

Quote:
Originally Posted by westcliffe01 View Post
How often do you anneal the case necks ? Have you bedded the action ? The multi group scenario is not unusual for a factory stock. Unless you did a bunch of work to it, maybe you have been lucky ? How many rounds down the tube ? Perhaps the throat is starting to go ?
West, I don't or haven't been annealing my brass. As far as the round count, it is something around 200-250. You could be onto something there with the bedding issue. USUALLY, the HS precision dosen't require it, but I do know of some that had to be done, and the results were amazing. It's funny, how someone can diagnose someone elses gun issue, but can't figure out there own. Thanks for the reply, I'll check that out!
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Old 05-20-2013, 08:44 PM
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Re: 308, five Shots, 2 Groups?????

6-7 firings with no anneal, wow, those necks should be ready to split on you. I think about 3-4 firings is about as far as you should go without annealing.

If you have a custom chamber that is "tight" on the neck and neck turn your brass, of course it will go longer, but for most of us we need to anneal every 3-4 loadings.

Your group would be typical for an SPS, which has a cheap POS stock, but a bedding job does make a big difference. Also be sure that when the rifle is loaded the way it is when you shoot it, that the barrel remains free floated. I suggest using a playing card instead of the $ bill to check for free floating. Many stocks deflect more than the thickness of a $ bill when loaded up.
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Old 05-20-2013, 08:49 PM
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Re: 308, five Shots, 2 Groups?????

Quote:
Originally Posted by westcliffe01 View Post
6-7 firings with no anneal, wow, those necks should be ready to split on you. I think about 3-4 firings is about as far as you should go without annealing.

If you have a custom chamber that is "tight" on the neck and neck turn your brass, of course it will go longer, but for most of us we need to anneal every 3-4 loadings.

Your group would be typical for an SPS, which has a cheap POS stock, but a bedding job does make a big difference. Also be sure that when the rifle is loaded the way it is when you shoot it, that the barrel remains free floated. I suggest using a playing card instead of the $ bill to check for free floating. Many stocks deflect more than the thickness of a $ bill when loaded up.
Again, you could be onto something there too, with the brass. Some of it is starting to split, and I discard it as I see it. Maybe it is time to disard this brass, and break in some new stuff. I keep forgetting this is NOT the good stuff. Duh, I feel like an idiot now. Too much going on recently! That makes more sense then any of it!
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Old 05-20-2013, 08:59 PM
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Re: 308, five Shots, 2 Groups?????

Yes, the brass gets hard and the properties change. With that the springback changes and neck tension becomes inconsistent.

If I were you, I would anneal them anyhow unless you have a bunch in reserve. I reworked a big batch of military "LR" brass recently and found a bunch of split necks right off the bat, even though it had never been fired... So I decided to anneal it all and then full length size it. I figured that anything marginal would split when I FL sized it and as it turned out, none did.

So at the end it was just a few % of the new brass that probably didn't get annealed properly in the first place and then split during the necking down process.
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Old 05-21-2013, 09:06 AM
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Re: 308, five Shots, 2 Groups?????

Based on what I read, I'm going with neck tension issues due to brass overuse, replace or anneal the brass and if the issue persist clean powder and copper from your rifle then shoot it.
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