Barrel overheating question.

[kritos666]

I have a hart 22" bull barrel that shoots great when cold/cool. However after about 7 rnds it really heats up and accuracy seriously drops off.

.4" groups @ 200yrds (cold)
1.5" groups @ 200yrds (hot)

.308 Win BTW

My question is would fluting my barrel really make a difference? If I send it off, its going to take a minimum of 12 weeks. Not to mention it will cost me a bit.

What do you guys think?

 

[Eddie Harren]

Bedding?

 

[fullersson]

A Hart bull barrel shouldn't open up that much after seven shots. I would to check and make sure the barrel is properly floated so that when it heats up it's not touching some part of the stock. Brian Brown.

 

[kritos666]

it seems to be bedded, I can see a tiny bit of what appears to be glass.

it floats in the stock (McMillan A1 if it matters)...

however the fact that you both pointed to stock, I can look into that. Once I confirm that it is bedded, do you have any suggestions?

if not bedded, then I suppose this is my excuse to get that McMillan A5 i wanted (and get it bedded of course)

Thanks for the replies.

 

[Eddie Harren]

I would make sure the barrel is not touching or, "slapping" the stock when fired. Are you using a bipod or a rest?

 

[kritos666]

The barrel does not touch, in fact I can tap the end of it and you can see the gap. It may however be too close and "slap" when fired. I am using a rest (Caldwell Rock Front Shooting Rest and rear bag)

 

[WyleWD]

What powder & bullet weights are you using?

 

[NorCalMikie]

After you shoot a few rounds and the barrel gets hot, run a $ bill between the barrel and forend and see if there's any tight spots. Then use a $20. It's a little thicker?

 

[kritos666]

Excellent suggestion on the 20$

My barrel likes .. Nosler 168gr. custom competition and 45.5gr. Varget. CCI primers 200 .0020 off lands

I'm just finishing the load testing. I still have to test 45.6 and 46.7 (ran out of time at the range) I haven't gotten out the chrono yet

 

[NorCalMikie]

Who cares how fast they're going as long as they're going in the same hole? You don't have to be fast to be accurate!
Try for maybe 1/16" between the barrel and forend.
If it's tight, stick a shim under the front of the action in the screw area as a quick fix till you can make it premanant.
If that makes a difference, you'll know what you need to do.
Maybe bed? Shim? Pillars? Open up the barrel channel? Whatever it takes.

 

[kritos666]

I know a bit .. but there is plenty to learn.. I'm not so sure the stock is bedded, note attached pix. There is a sizable gap between the barrel and the stock tho, also note attached pix. The gap goes quite a way back to the action, however perhaps not far enough.

thoughts.

 

[NorCalMikie]

First thing I would do is get that snake out of the barrel channel so you can see what's going on. ;D (looking 8) 8) 8))
Looks like the stock has been bedded. Run a $ bill under the barrel. Got clearence all the way back? Kinda looks like the barrel may be off center in the channel but it may be the lighting?
Pop a few rounds and see if it still has clearence all the way back. Could be binding after it heats up?
If the $ bill drags anywhere between the "snake" and the forearm, you might be able to run some sandpaper and a piece of round stock in the channel to get daylight. Too much is better than not enough.

 

[jo191145]

My quess,,, Its not heat. Your barrel does not like the powder your using.

Try this. Shoot your 6-10 rds until point of impact accuracy changes.
Allow to cool.
Shoot again.
My bet is accuracy and or POI does not improve.
If your accuracy issues disappear its heat.
If the problem remains its a barrel discontent with the fouling in it.

 

[jonbearman]

What about the fact that the first few inches ahead of the recoil lug appear to be bedded to the barrel. Alot of people think it is a good thing to bed the first few inches of the barrel.I would grind it enough(the bedding ahead of the recoil lug )so it doesnt support the barrel and try that.You can always put it back easily if you feel it is necessary.

 

[kritos666]

Thanks to all for the input

As for clearance.. I can slide 3 dollar bills back to the edge of the bedding without any contact (sorry for the pix .. they were the best I could do).

I will definitely try to sand down that area.. that area definitely touches the barrel.

As for powder I have tried 3 types .. Hodgton BLC-2, H335 and Varget. All spread as barrel heats H335 is most consistent as far as groups spreading, however the the group sizing is crap 1.5" @ 200.

I am open to suggestions. Although I realize I am opening a can of worms asking for peoples best powder.

 

[bozo699]

kritos666,
I seriously doubt the bedding in front of the lug is the problem, it's possible but doubtful IMO, I would rather think your magazine or bolt or something in that area is touching, have you checked for carbon? best of luck.
Wayne.

 

[kritos666]

Well all the same I sanded off 1/16" give or take. the magazine is internal. I clean the rifle after every time I take it out. I have cleaned it out about a month ago for copper fouling (but not being a hardcore bench shooter, I don't remove the fouling ever time I shoot it) As for checking for carbon, I'm not sure I understand where/how you mean. Please explain.

Also, I'm headed out to the range and will test the dollar bill trick on the bedding after the barrel heats up. I will take notes and report my findings.

Thanks again for all the pointers !

 

[BoydAllen]

First of all, all of this talk of dollar bills and clearance is antiquated. I would be looking for a sixteenth of an inch, minimum, for a target rifle, all the way back to the action. The other thing is that you cannot see if bedding is correct by looking at it. It takes a dial indicator and a magnetic base, or something similar. Bedding can look good and be bad. Third, what shape are your groups? Are you using wind flags? What sort of rest and bench? How are you holding the rifle? Erratic results can happen for a number of reasons, and easily be diagnosed as to their cause. I am not trying to pick on you here, just to bring up some issues that may shed some light on potential sources of your problem. Good luck. If you figure out something that works, let us know. One more thing, light loads with some ball powders can produce a ton of fouling, pretty quickly, and one more question. How do you clean?

 

[commando57]

Is that barrel machined like that?

 

[AWLEAPHART]

Two things.
Fist is I have been told by 3 Different smiths that they have not had good luck in the past with the stock being bedded pass the lug.
Second, I had a rifle that was like changing POI and the bedding to me look great. So i let Robert Gradous take a look and the rifle and it was moving in the stock. I mean moving very very little movement. He rebedded the lug and it fixed the problem.
Also I knew a fellow shooting a 308 that had a problem kinda like your and it was the action bolt touching the threads on the barrel. He shorten the screw and was good to go.
Anthony