Interesting observation

[Varmint Hunter]

Do you normally get good results shooting different powders over the top of each other?

I have been doing that for 50 years and have never noticed any difference either way. I belong to two shooting clubs. The closer one is 150 miles from my home. For that reason, I typically have many bullets and powders to test on the same day.

 

[X'n Tex'n]

In my endless effort to find the perfect load I observed something interesting.

I loaded 9 rounds of several different loads to be tested. This would allow me to fire 3 - 3 shot groups of each load. I shot the groups in a round robin fashion.
First group of load #1 - then first group of load #2 - then first load of #3 and so on. Eventually I'd get back to load #1 again to retest that load. This would allow the groups to be fired under different bore conditions.

I fired 6 fouling loads the day before the tests began. Everything was chronographed with the Garmin.

The two things that I noticed were:
1. Velocity of each load continued to rise throughout the testing - not dramatically but noticeable
2. Fouling conditions definitely affected group size. Virtually all the loads shot the tightest groups on a relatively clean but fouled bore. Groups did open as the barrel accumulated more fouling.

FWIW - I was shooting a custom 6.5PRC with a 23.5" Bartlein carbon bbl.

After about 300 rounds through a bartlein 7mm carbon wrapped barrel, chambered in 284 win, I replaced it. Two bullets and five powders, I couldn't get it dialed in for my needs. I think Bartlein dropped the ball with these carbon barrels. After chambering this barrel, threading muzzle, etc., the carbon fiber shroud doesn't seem to be bonded well to the actual barrel. At least compared to others" carbon wrapped barrels I've worked with.

So, technically, it's not a free floating barrel anymore, is it? Could be your problem as far as accuracy is concerned.

 

[Varmint Hunter]

After about 300 rounds through a bartlein 7mm carbon wrapped barrel, chambered in 284 win, I replaced it. Two bullets and five powders, I couldn't get it dialed in for my needs. I think Bartlein dropped the ball with these carbon barrels. After chambering this barrel, threading muzzle, etc., the carbon fiber shroud doesn't seem to be bonded well to the actual barrel. At least compared to others" carbon wrapped barrels I've worked with.

So, technically, it's not a free floating barrel anymore, is it? Could be your problem as far as accuracy is concerned.

I've got a few Bartlein Carbon wrapped barrels. Here are a few groups that I shot this Monday from a 6.5PRC with a Bart-Carb.
The target backer is at a lasered 418yds.

 

[X'n Tex'n]

I've got a few Bartlein Carbon wrapped barrels. Here are a few groups that I shot this Monday from a 6.5PRC with a Bart-Carb.
The target backer is at a lasered 418yds.

View attachment 611216

Nice! Looks like you got a good one. I actually like Bartlein barrels. I have a couple on f-class rifles that shoot consistent sub .250, with the occasional sub .125. It's why I went with theirs instead of Proof or C6. Expected better quality. I gave it to my son. We'll probably rechamber it to 7ss and run 184/190's. Not dead yet

 

[Beluebow]

I have been doing that for 50 years and have never noticed any difference either way. I belong to two shooting clubs. The closer one is 150 miles from my home. For that reason, I typically have many bullets and powders to test on the same day.

Interesting how we all have different experiences with nearly the same things.

It's been "my experience" that like powders (say RL16 and RL23) shoot fine over the top of each. Throw H4350 into the mix over the top of RL23 and it takes a few shots for it to settle down. I've seen the same thing with Varget and 8208. Maybe it's a double based powder vs a single base thing. Or maybe it is as simple as a product line thing.

Like your thread title says....interesting observations.

 

[DylanWalsh]

@X'n Tex'n did you borescope the Bartlein you couldn't get to group? Or figure out what the issue was?

 

[VinceMule]

Some can be pretty rough.

You have been warned.

 

[X'n Tex'n]

@X'n Tex'n did you borescope the Bartlein you couldn't get to group? Or figure out what the issue was?

Yes, the issue is, I believe, the loosely bonded carbon fiber shroud. If it were bonded properly, there would be no no gaps, air pockets or movement between the barrel and carbon fiber shroud. It is akin to your barrel touching the stock at various point along its length. This causes inconsistent harmonics which moves your poi from shot to shot. This is why a free floated barrel is desirable. I wasn't getting MY desired group consistency. At $800 these barrels should be better made.

 

[Varmint Hunter]

Yes, the issue is, I believe, the loosely bonded carbon fiber shroud. If it were bonded properly, there would be no no gaps, air pockets or movement between the barrel and carbon fiber shroud. It is akin to your barrel touching the stock at various point along its length. This causes inconsistent harmonics which moves your poi from shot to shot. This is why a free floated barrel is desirable. I wasn't getting MY desired group consistency. At $800 these barrels should be better made.

Any Bartlein bbl that displays the issues that you have described should be return to Bartlein. I had an accuracy issue with a new custom rifle. I eliminated every variable I could think of and then decided that the barrel was the issue. I called Bartlein and told them that I believed that the barrel was causing the inaccuracy issues. I was told to ship the barrel back along with various other info like loads tested, results on paper, cleaning routine, etc.

I had my gunsmith remove the barrel and send it back to Bartlein. The only issue with doing what I did was that I'm told that Bartlein is now so inundated with work making barrels for the military (US or other?) that they just don't have time to address complaints like they used to.

In the end - Bartlein claimed that after thorough review and inspection that the barrel was well within specs. The barrel was shipped back to my gunsmith. The rifle was reassembled with the exact same components and, oddly enough, it shoots well. Neither myself nor my gunsmith could explain exactly why or how this happened, but we were both just happy that the rifle was shooting as any full custom rig should.