Rifle Groups Getting Worse

[texasbilly]

My new Weatherby Vanguard 243 winchester rifle has a plastic stock. I loaded 16 rounds of ammunition to sight the rifle in for hunting. To test the loads, I mounted a 36x scope. On my first attempt to shoot the ammo, I fired a small 5-shot group at 100 yards (sub inch). I left the barrel cool while I shot a different rifle. On my second attempt to shoot the ammo, I fired a larger 3-shot group at the same distance (1-1/4". Again I left the barrel cool. On my third attempt to shoot the ammo, I fired an even larger 3-shot group (1-3/4"). After leaving the barrel cool, I shot a 4-shot group that was even worse that the third (2+").

I went through the usual issues regarding accuracy: barrel crown is good; scope mount screws are tight; stock screws are tight; trigger is good (not great, but good); shooting conditions were excellent (50 degrees, calm, low humidity); etc

Ideas of what may be causing this problem of the groups getting bigger over time? Solutions?

 

[josebd]

Bore needs to be clean?

 

[Pyscodog]

You may not want to hear this.......but I bought a NIB Weatherby Vanguard 243. I put just a handful of rounds through it then ordered a new B&C stock with aluminum bedding block. I used a NIB Leupold scope as well. Inch and a half groups were the best it would do. No exceptions. After 200+ rounds, took it to my smith and wanted him to cut 4 inchs off the barrel and recrown it but he talked me in to only cutting two inchs. We cast the cut off end with cera safe ( I think thats whats it called) and when we knocked the plug out, there weren't any riflings in the stub. Just very shallow scratch marks. Well, I guess that voided the warranty. It helped a little but not much. I kept the stock and sold the rifle to a guy to rebarrel.

 

[gambleone]

Was that a clean bore when you started shooting?

 

[texasbilly]

Cleaned after every trip to the range. I'm wondering if free floating the barrel, and glassing the stock may help Thoughts?

 

[josebd]

Did you clean with copper removal?

 

[LCazador]

Cleaned after every trip to the range. I'm wondering if free floating the barrel, and glassing the stock may help Thoughts?

Do you have any way of verifying your cleaning regimen? Bore scope? Sure sounds like a bore fouling problem. Are you using a carbon removal product? I've been working on a Ruger All American in 308 for a friend and the barrel seems to foul out in 12 rounds. Heavy carbon deposits that are easily removed with C4. It was doing the same thing. By the time I shot the last group, 4 groups of 3 shots, groups opened up.

 

[DGP4]

I'd go ahead and bed the stock or, better yet, get a better stock.

 

[texasbilly]

What makes me think it may be a bedding problem is the fact that, while holding the action firmly, I can wiggle the barrel left and right. Although the action screws are very tight, it seems that the barrel may be moving around when I shoot. Thoughts?