your thoughts on my groups opening up...

rifle is a 308 30" mcgowen 10 twist bull on a wsm action, load is 44.0 varget w/ 168 smk. bushnell 4200 6-24x50.


symptom: i can cloverleaf the first 10rds (less than 3/4 moa) but by rd 15 i am walking low by 1 inch and by rd 20 i am low left and opened up to 2 moa. this is very consistant w/ this rifle and probably not shooter error as it is only w/ this rifle. i am thinking it is a heat issue and is just one of those things where it is what it is, but i know that the veteran shooters have shed light on several of my other problems here and would like your input. total time from round#1 to #20 is less than 10 minutes....

:-\ :'( :-X....Gheezzzz, A few thoughts:

1) Barrel is free float? (I'm sure you have ran $10,000 of $1.00 bills down it at this point)

2) Bedded action? (I'm thinking you've put it to sleep by now?)

3) Timed & trued the bolt face?

4) After the first 10 rounds, gave it a quick 'n dirty barrel cleaning just to see what the next 10 rounds would do?

5) After the first 10 rounds, sang "Cum-by-ya" to it for 2 minutes, then shot the next 10 rounds? (Hey.....if you've never tried it.....don't knock it!!)


Dave

How many range sessions has this pattern repeated itself?

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Originally Posted by Smokey262

How many range sessions has this pattern repeated itself?

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choate centerfeed stock, this has been fairly consistant for about 500rds, total count is 800+/-, changed scopes etc. not bedded, just the pillar bedding of the stock.

no t&t but am getting almost no case stretching, minmal trimming so i am thinking i am pretty true, when the action was a 300wsm i went 12 firings on the brass w/ only 2 minor trimmings...

I'd glass bed the action. Slow down on how fast your shooting those 10 rounds, wait a minute or two between each shot and let us know how it does after a bit of tweeking.

Hi Hershy, a friend of mine had a similar problem w/ CZ american 30/06. Except his groups opened up and shifted after just two shots. I bedded his action w/ devcon (no pillars) and the problem went away w/ no other adjustments. Another thought: maybe your barrel missed or wasn't properly heat treated. Try the devcon first. Or, after ten rounds let it cool for 5 to 10 minutes. If using Devcon bed the first 1 1/2" to 2 inches ahead of the lug. Thats a pretty long barrel/ weight hanging off the front of that action. Dale

I think you nailed it with barrel heating. Next time out let the barrel cool completly to cold between shots. Both my 223 and 7mm RM do the same thing you described but when left to cool completely they both make one ragged hole groups.

No info on how you are shooting, rest, bipod, etc. Focus on your position and the way you mount the gun for each shot. Doesn't really matter how you are doing it, just has to be the same "everytime". Gun will naturally work it's way back with recoil, shooter naturally keeps getting closer to the scope or sights with each shot fired. Not trying to take anything away from you as a shooter, just a problem many people have and forget about sometimes.

Do you dismount the gun between shots?

How is the gun balanced front to back? Nose heavy?

Later, Brad

I had this problem with my 12fv 308 when I bought it. I ordered a stockade stock and when i was talking to Kevin he siad I had build up of cooper. he siad to pour cooper solvent down the barrel and leave it there over night. That did the trick... now I can go all day and hold sub-moa...
Pete

+1 12fv 308 Copper build up will make a barrel heat up a lot faster especially if your shooting over 10 rounds at a time. Clean clean clean.