308 Slow barrel help???

[BW64]

To me (I'm not an expert), it sounds like the barrel's bore has some rough surfaces and pitting that are catching the copper jacket and stripping layers off of parts of the bullet. This "stripping" action is uneven and results in a bullet with a damaged center of gravity. This could lead to unexpected excess spin drift. I've seen this problem happen at barrel-burner speeds like 2900-3000fps, but disappear at lower speeds. It's also possible that the throat has a pretty gnarly burr on one of the lands from potentially sloppy chambering.

If you've cleaned your barrel with a good bore cleaner like Montana Extreme 50BMG, Boretech Eliminator, or Sweets 7.62, and that didn't help, then check the muzzle end with a caliper to find the groove/bore diameter. If the bore diameter (on the lands) is between 0.298 and 0.301, then you're good. The groove diameter should be somewhere between 0.307 and 0.309. These are pretty wide ranges, but they're guidelines a wise old man once taught me.

If all else fails, try wrapping a slightly undersized (7mm) stiff nylon brush with a bunch of patches and coating it in JB, Iosso, or Flitz. Run that up and down the barrel (not out the muzzle though) until you feel like the barrel has been adequately polished. If that doesn't work, then you really do have a bad barrel that needs replacement.

The good news is that you can now get Remage barrels for not much more than a normal barrel blank. They use a savage-style nut so you can swap your barrel at home. I think Criterion makes them.

My $0.02[/QUO

I had the same problem with the stock barrel. Got no accuracy after 2400 fps. A friend checked the throat & sure enough it was bad. Not the first one I've heard of in Rem 700. Switched to Criterion Remage & never looked back. I shoot 1000 yard silhouette with moa targets. No problems since.

BW

 

[JasonT]

You can also use a piloted throating reamer (uni-throater or standard) to clean up the throat if it was cut unevenly.

 

[ryguy00]

Sorry guys I've been sidetracked. Well, the consensus is that I've got a slow barrel. It has the accuracy I need. It can reach the speeds I want. But it can't do both at the same time. Accuracy is more important, so they're staying loaded slow.

I have a solution to this problem. This barrel is going on a different rifle that will not be so demanding of accuracy. At that point, it's getting lighter and cheaper bullets pushed faster to be shot shorter distances at larger targets. Until then, I've got a really accurate "30-30"

 

[ryguy00]

What you want may not be what your gun wants?
There is a way to have both, but it may require that you crown and shoot until you find the sweet spot closer to the speed you are looking for.

Crown and shoot until I'm 400 FPS faster? Lol. No thanks. I'll just buy another barrel.

 

[rifleman700]

Ok, I've got a 308 built on a Remmy LA with a pre chambered shilen 1:10 shooting 175gr vld's. Starting loads are around 2300 with max around 2600 in the berger book. I'm using Lapua brass and Varget and have pushed them all the way up to 2950 before getting pressure signs, however, they just will not freaking shoot at any respectable speed. Backing them down to low-mid 2200's has them grouping in the .4's and .3's which is the accuracy I need for my intended use. That's absurdly slow though! Anything faster and groups open to 3/4-1 MOA which is not good enough. Now I've heard of "slow barrels" before, but is this "normal" for a slow barrel to be THAT slow???

Yes, I'm aware that changing bullets and bullet weights will bypass this problem, and I plan to do so, but I'm just baffled by this.

Barrel length? Varget needs 24" or longer to get full burn / pressure in a 308.

 

[fm1947]

Ok, I've got a 308 built on a Remmy LA with a pre chambered shilen 1:10 shooting 175gr vld's. Starting loads are around 2300 with max around 2600 in the berger book. I'm using Lapua brass and Varget and have pushed them all the way up to 2950 before getting pressure signs, however, they just will not freaking shoot at any respectable speed. Backing them down to low-mid 2200's has them grouping in the .4's and .3's which is the accuracy I need for my intended use. That's absurdly slow though! Anything faster and groups open to 3/4-1 MOA which is not good enough. Now I've heard of "slow barrels" before, but is this "normal" for a slow barrel to be THAT slow???

Yes, I'm aware that changing bullets and bullet weights will bypass this problem, and I plan to do so, but I'm just baffled by this.

If it's a new barrel send it back to Shilen

 

[ryguy00]

Barrel length? Varget needs 24" or longer to get full burn / pressure in a 308.

It's a 24" or 26", I forget. It has no problem reaching full burn/pressure. Again, I can push it to high 2800's - low 2900's as it is. The bullets just won't shoot accurately enough there. Half moa is the absolute MAX acceptable.

 

[ryguy00]

If it's a new barrel send it back to Shilen

Old barrel. 3 or 4 years old. Not that it has that many rounds through it, I just bought it that long ago.