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175 VLD vs 168 A-Max in 300WSM

 
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  #1  
Old 07-14-2008, 05:53 PM
mkg mkg is offline
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175 VLD vs 168 A-Max in 300WSM

Hey guys I have a model12 VLP Savage (300WSM) that has a cold bore issue using 180 Nosler Ballistic tips . I am looking for another bullet to try . I'm concidering the 175VLD and the 168 A-max . The rifle is currently used to poke holes in paper but this is intended to be practice for the upcoming deer season. The rifle groups great at 100 , the cold bore issue didn't show until 200/300 yards . I'm 1MOA low and 1/2 MOA left cold bore. The following shots in the group are under an inch at 200 and right at an inch at 300 .
So, I want to try a new bullet manufactures to see if I can tighten the cold bore shot.
Also any other ideas ... I'm at a loss at this point .

BTW: I have tried different bullet weights ( but all Nosler BT's ) and seating depths from .012 off to .050 off the lands .


Thanks Mike
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Old 07-16-2008, 08:42 AM
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When I taught at sniper school we did an extensive amount of testing on the cold bore shot. In general we found that the better (smoother in particular) the barrel, the easier it was to predict the cold bore shot. We were working with H and S cut rifle barrels, btw. I do not think a different bullet choice is going to solve your problem. I would try two things; first get the barrel hand lapped by a good gun smith. I would also try only cleaning the powder fouling out of the barrel. We found that on some of the rifles that were a little finicky when totally clean, if we just cleaned the powder fouling out of the barrel but left the copper fouling in it the cold bore shot would become predictable. You can not do this forever, eventually too much copper builds up and accuracy suffers. We termed this the rifles "condition" as in cleaning condition it liked to produce a predictable cold bore shot.

If you chronograph the rifle you might find the cold bore shots velocity is different than the rest of the group due to the friction coefficient of copper and steel (bullet and barrel) until a little copper gets laid down and things even out.
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Last edited by Marine sniper; 07-16-2008 at 08:50 AM.
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Old 07-16-2008, 12:40 PM
mkg mkg is offline
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Marine sniper, Thanks for the response.

Yes , I can understand a difference in POI Clean cold bore vs Fouled cold bore .
The problem is that I can fire a four shot group (fouled cold bore shot flyer remaining shots around an inch at 200 ) let the rifle cool for 45 min to an hour . Shoot another group ( no cleaning ) and cold bore is out, the remaining rounds group as before.
If the fouled cold bore shot would group with the follow up shots I would be happy.
This leads me to believe that it is thermal.
Although unlikely ( read last gasp option ) it may have something to do with the barrel just not liking the Noslers . Beyond that I'll most likely rebarrel.

Thanks again
Mike
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Old 07-16-2008, 12:59 PM
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Quote:
Originally Posted by mkg View Post
Marine sniper, Thanks for the response.

Yes , I can understand a difference in POI Clean cold bore vs Fouled cold bore .
The problem is that I can fire a four shot group (fouled cold bore shot flyer remaining shots around an inch at 200 ) let the rifle cool for 45 min to an hour . Shoot another group ( no cleaning ) and cold bore is out, the remaining rounds group as before.
If the fouled cold bore shot would group with the follow up shots I would be happy.
This leads me to believe that it is thermal.
Although unlikely ( read last gasp option ) it may have something to do with the barrel just not liking the Noslers . Beyond that I'll most likely rebarrel.

Thanks again
Mike
Interesting, I have never seen that before.
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Old 07-16-2008, 01:55 PM
mkg mkg is offline
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Interesting indeed, None of the guys I shoot with has seen anything like this either. I originally thought it was me. But, I've had two more experianced shooters try to shoot groups with the same result.

If it were recoil induced like scope lash I would think it would occur on the first round and be fine the rest of the day.

If it were my handloads it would be random not always cold bore .

That's what leads me to believe it is a thermal characteristic of the barrel . Last option before I call Mr Shilen ,try some different projectiles and hopefully one of them will be less sensitive to whatever it is.

FWIW my 270 and 22-250 do not have this issue

I've only been shooting seriously for the last 7 months so I am WAAAAY over my head here . I really appreciate your input.

Mike
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Old 07-16-2008, 02:37 PM
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A new bullet is worth a try, can't hurt.
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Old 07-21-2008, 10:19 AM
mkg mkg is offline
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Well the barrel apparently does not like Nosler BT's in the cold bore . With limited testing the VLDs and A-max do not have the same POI issue cold bore. I shot six 2 round groups ( cold bore then follow up shot ) with three different loads the best set was just under an inch at 200 . I know not exactly a group , but I was more interested in the cold bore VS follow up shot than anything.
I was too deep into the lands but there were no over pressure signs . I'll adjust seating depth and continue load development .
I also found that I can seat well into the lands and still mag feed.

Mike
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