Proof barrel Issue

[gerpwaller]

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.

Did it shoot when the barrel got warm? I can try putting the action in a strike nuke chassis to see if that makes a difference.

 

[Lee7588]

Did it shoot when the barrel got warm? I can try putting the action in a strike nuke chassis to see if that makes a difference.

If you change the chassis that will tell you if that was the issue or not. Then your problem is corrected or you cross that scenario off the list. Have you started by checking out the basics like scope bases and rings are tight, action screws aren't pressing on the bolt, etc?

 

[jskmtd]

Yes after the first shot it would stack the next 3 on top of each other.

 

[Bob Milek]

Hi Guys,

I have a 308 with a 22" proof barrel on a tikka action bedded and floated in an Iota Eko stock. I'm having some issues with it that seem very strange to me. I will start off by saying getting a replacement barrel is likley not an option as I was gifted this barrel and it was pulled off a PGW build. My gunsmith (the same one who installed it on the pgw in the first place) then turned the barrel down so that it fit my action and cerakoted the metal on the barrel OD green to match the green in the stock. I am aware of the possibility that this extra work may have compromised the integrity of the barrel but the results are still confusing to me. The rifle that the barrel came off of had a very low round count and for indications was very accurate (3 different bullets shooting 5 round groups inside 0.75 moa). I realize that since Hornday's podcasts on group sizes that 5 rounds is statistically meaningless but there was no indication that it wasn't a shooter.

Shooting both 168 gr GMM and 168gr federal Terminal Ascent bullets the first 3 shots are inaccurate (group about 2.5 moa) before it settles in to do 10 and even 20 round groups inside 1.5". After seeing this trend a few times I decided to do a cold bore accuracy test shooting 2 shots at two different targets on different days. The 1st shot group is strung largely vertically but from about the 7:00 position to the 2:00 position shooting a 2.5" group after 7 cold bore shots. The second shot group is strung horizontally 2.5" with only about 1" vertical dispersion. Dispersion of both groups is realatively even so it's not like it's grouping well with the occasional flyer. After about 3 shots the rifle will group both loads into 1.5" or less. I have tested this 3 times. Twice doing 10 round groups and once finishing the box and doing a 17 round group all three of which were under 1.5 moa (one group was done at 360 yards the rest at a bench at 100 yards). This is what prompted me to do a cold bore test to see if I can expect it to be reliable hunting rifle. I've tried researching if anyone has seen similar issues with a proof barrel with no luck. I can't really complain much since I was gifted the barrel but it makes no sense to me, and is making my brain itch, why the barrel would seem to need a bit of heat in order to be accurate.

I've been shooting off of a sand bag with a sand bag for a rear support. I have other rifles that I can routinely shoot 10-20 groups into 1-1.5 moa so I know the issue isn't simply my shooting. I'm open to any theories as to why this might be the case. If the general consensus si that the barrel is pooched from the extra work needed to convert it to a tikka compatible barrel then so be it. It still doesn't explain why it shoots great when warmed up and terrible when cold.

Cheers,

Gary

You might also check to see if the barrel is truly free- floated. If it is, try building up a pressure point just behind the front of the forend of the stock. The majority of rifles will shoot best when properly bedded and free floated, but the occasional will prefer a slight bearing on the barrel to shoot well.

 

[gerpwaller]

Yes after the first shot it would stack the next 3 on top of each other.

I'll double check it in the strike nuke with the GMM and then again with the TA bullets. I'll probably check the TA ammo in the target set up that is in the strike nuke now fisrt though A friend of mine has a similar set up except on an R700 action (mine is another tikka) that will try a 20 round group with that ammo as well so we should get an idea of the accuracy potential. I just did a five round group of the TA ammo ( 2 shots yesterday and 3 today) with a T3X battue. results were 2.5". I figure I'm shooting with about a 0.25-0.5" handicap on that rifle as I'm using a Vortex PST 2 1-6 optic and the cross hairs are over 1moa. It shoots possibly marginally better than the proof rifle.

 

[gerpwaller]

You might also check to see if the barrel is truly free- floated. If it is, try building up a pressure point just behind the front of the forend of the stock. The majority of rifles will shoot best when properly bedded and free floated, but the occasional will prefer a slight bearing on the barrel to shoot well.

I did check that it was free floated. I had to open up the barrel channel myself and then before bedding that was double checked by my Smith.

 

[Barehandlineman11]

Sounds like something is under stress. Who bedded it? Pillars? Not all smiths can bed

 

[gerpwaller]

Sounds like something is under stress. Who bedded it? Pillars? Barrel isnt touching?

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.

 

[FullCurl8]

I'm always suspicious of a low round count barrel take off for sale, especially a Carbon Fiber one. If it shot great it would still be on the rifle. Eventually, after you've checked bedding again with a dial indicator and all the other good suggestions here, I would want to know the barrel torque your Smith used if any. Am I to understand he machined the OD of the Carbon Fiber barrel? I don't believe ammo choice is the problem but might be a combo? Often the old owner will say what it shot well with.This will be a barrel problem.

 

[Barehandlineman11]

Dollar bill isn't enough thats very old school method. Especially on carbon proofs. And not all smiths can bed. Id hold your gun barrel and stock in hand and loosen bottom metal see if you can feel it move. If it moves its under stress. A clean bed job and stress free bed job are seperate animals

 

[codyadams]

If impacts change after shooting and tightens up, I would look at bedding first. How good a bedding job looks doesn't matter squat if the person induced stress into the action while they bedded it. If you have a chassis that you can shoot well with, throw it in that and torque it down properly, and see if things change.

There are a ton of ways to bed an action and have the bedding job look clean. There are only a couple ways to bed an action and have it be stress free.

 

[Elk Hunter 338]

If impacts change after shooting and tightens up, I would look at bedding first. How good a bedding job looks doesn't matter squat if the person induced stress into the action while they bedded it. If you have a chassis that you can shoot well with, throw it in that and torque it down properly, and see if things change.

There are a ton of ways to bed an action and have the bedding job look clean. There are only a couple ways to bed an action and have it be stress free.

 

[gerpwaller]

I'm always suspicious of a low round count barrel take off for sale, especially a Carbon Fiber one. If it shot great it would still be on the rifle. Eventually, after you've checked bedding again with a dial indicator and all the other good suggestions here, I would want to know the barrel torque your Smith used if any. Am I to understand he machined the OD of the Carbon Fiber barrel? I don't believe ammo choice is the problem but might be a combo? Often the old owner will say what it shot well with.This will be a barrel problem.

My Smith installed the the barrel on the first rifle, verified the accuracy with the 5 round groups (before the hornady you groups are too small podcast) and then removed it. There are some extenuating circumstance that ended up with me getting the barrel but they had nothing to do with it not shooting. Otherwise I totally agree, if it seems too good to be true it probably is. I have tested it (although not as extensively) with gmm and it behaved similarily. I will do a cold bore test with the GMM. I will also verify all the action screws and everything else is torqued. If I get teh same results I will fully cede that it is the barrel.

Yes he machined the outer diameter of the shank down to fit the tikka action. I think he had to take down a bit of the carbon as well to smooth out the transition.

 

[gerpwaller]

Dollar bill isn't enough thats very old school method. Especially on carbon proofs. And not all smiths can bed. Id hold your gun barrel and stock in hand and loosen bottom metal see if you can feel it move. If it moves its under stress. A clean bed job and stress free bed job are seperate animals

Thanks for the advise. I will check that. It's not the first rifle he has bedded for me (and himself and other customers) but that's not to say there isn't a chance it is under stress. When I transfer the action to the Chassis I will look fo that. He's as confused as I am as to why it seems to need a bit of heat to shoot and wants to figure this out as well.