Proof barrel Issue

[FullCurl8]

What does 10' over mean?
So you guys took some factory ammo, pulled the bullets, dumped just the powder, put in some different powder, and put bullet back in?

 

[Lee7588]

What does 10' over mean?
So you guys took some factory ammo, pulled the bullets, dumped just the powder, put in some different powder, and put bullet back in?

I think it means 10 rounds over varget and 10 rounds over ramshot

 

[Laguna Freak]

Barrel isn't touching, we did the dollar bill test on it. My smith bedded it for me and was very happy with how the bedding turned out. Said it was one of the celanest bedding jobs he'd done.

Dollar bill is not enough sometimes IME. I've gone to business card clearance.

 

[cohunt]

Are you saying that by shot #3 it starts to group tighter?
As you are doing 2 shot cold bore testing-- I was assuming that by the 3rd shot it grouped better.... but maybe I'm reading into it.

I wouldn't say that 2 shots of 308 has totally warmed up a barrel enough to start any significant thermal expansion--- it takes 3-5 shots of my 308 to really start feeling significant heat in the barrel.

Have you done this "2 shot cold bore testing" with other firearms to make sure your not "warming up" the shooter? It odyen takes a few shots to het me warmed up, especially if I change firearms-- I need to get used to the trigger, stock fit, recoil, and weather conditions of each particular rifle session before I really start to shoot well. --- just a thought

 

[gerpwaller]

Are you saying that by shot #3 it starts to group tighter?
As you are doing 2 shot cold bore testing-- I was assuming that by the 3rd shot it grouped better.... but maybe I'm reading into it.

I wouldn't say that 2 shots of 308 has totally warmed up a barrel enough to start any significant thermal expansion--- it takes 3-5 shots of my 308 to really start feeling significant heat in the barrel.

Have you done this "2 shot cold bore testing" with other firearms to make sure your not "warming up" the shooter? It odyen takes a few shots to het me warmed up, especially if I change firearms-- I need to get used to the trigger, stock fit, recoil, and weather conditions of each particular rifle session before I really start to shoot well. --- just a thought

I have shot enough that it is not "warming up the shooter". I don't go from a 2.5" shooter to a 1" shooter after 3 shots. After 3 shots the rifle does seem to tighten up the groups from the 3 times I have tested it. I realize that is not a lot of heat in the barrel which is why I am so perplexed by what I am seeing.

 

[gerpwaller]

I think it means 10 rounds over varget and 10 rounds over ramshot

Sorry, far thumbs typing on a phone don't always work out properly. Also, I need to proof read more.

 

[gerpwaller]

Are you saying that by shot #3 it starts to group tighter?
As you are doing 2 shot cold bore testing-- I was assuming that by the 3rd shot it grouped better.... but maybe I'm reading into it.

I wouldn't say that 2 shots of 308 has totally warmed up a barrel enough to start any significant thermal expansion--- it takes 3-5 shots of my 308 to really start feeling significant heat in the barrel.

Have you done this "2 shot cold bore testing" with other firearms to make sure your not "warming up" the shooter? It odyen takes a few shots to het me warmed up, especially if I change firearms-- I need to get used to the trigger, stock fit, recoil, and weather conditions of each particular rifle session before I really start to shoot well. --- just a thought

I haven't felt the need to do the 2 shot cold bore testing with any of my other rifles as I haven't seen that trend. On my tikka T3 in 270 the first three shots typically group and then after that it opens up which makes more sense as it is a pencil barrel.

 

[Lee7588]

Sorry, far thumbs typing on a phone don't always work out properly. Also, I need to proof read more.

No problem there are times I try to tye something w/o glasses and go back to read it after I hit send. And I'm like that was the wrong blurry letter. . Thank the good Lord for scopes and binos

 

[Techy]

I had a cold bore issue I thought was the barrel, I replaced the barrel and still had the cold bore issue. Turns out it was the bedding. Ground out the bedding and rebedded it and things are good. Expensive lesson.

This is good to know.

 

[gerpwaller]

A little update. My Smith checked the bedding for movement and the barrel only moved 0.002" when loosening the action screws so it doesn't appear to be the bedding. As far as the terminal ascent bullets go his rifle (a Bergera b-14 with 20" IBI barrel and a grayboe stock) shot 10 rounds under 1.5 moa with the ramshot load and the bullets loaded to SAAMI max length. I shot the TA bullets over 44gr of Varget yesterday from my target rifle and got a 1.2 moa 10 round group. Definite improvements over the factory loads. I also did a relatively fast group with 168 gr gmm out of the proof 308 and it was just under 2 moa. It may just be that we ended up doing a little too much to the barrel and introduced stress enough stress that it is now a 2 moa rifle. I'll keep you posted. I will do some more cold bore groups with gmm and also strings to see if the trend continues regarding the heat in the barrel.

Cheers

 

[Lee7588]

I think in a previous post you had a chassis that you could swap out with the stock. Did you ever change them to remove the stock from being a factor?

 

[FullCurl8]

If that's the case, I would add an adjustable pressure point to the tip of the forend to Tame the barrels movement, give it a few PSI and tweak as you go. Or epoxy a permanent one in place and sand as you go at the range. It may not win a PRS shoot but often it shoots under 1 moa.

 

[gerpwaller]

I think in a previous post you had a chassis that you could swap out with the stock. Did you ever change them to remove the stock from being a factor?

I have not had the time to do that. I am still planning on doing that. I may be that despite the bedding being good the stock is still an issue.

 

[gerpwaller]

If that's the case, I would add an adjustable pressure point to the tip of the forend to Tame the barrels movement, give it a few PSI and tweak as you go. Or epoxy a permanent one in place and sand as you go at the range. It may not win a PRS shoot but often it shoots under 1 moa.

That's not a bad idea. Similar to what they do for timing Ruger #1 rifles I'm guessing? It would be a lot of work with trial and error but if the rifle shoots then on the end it's worth it. Not that this needs to be my primary rifle. I've got others that shoot better but I have a lot of ammo that was gifted to me for this rifle that would be good to be able to use and not be frustrated.