Benchmark Barrel cleaning ?

W

Wannebe

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I've read here some time ago that these barrels seems to shoot best when kept clean.

I was fortunate to get a 3 x groove BM 5.5mm barrel. I've been testing this in my Dawson action for some time now. Here is the interesting thing ..... I decided not to clean it and keep shooting. After about 250 - 300 shots it seems to settle and accuracy remain excellent. To date I've shot +/- 800 pellets and accuracy is spot on. (I'm not shooting at bench targets but at 40m I can keep them within 10-15mm, CTC, wind or no wind)

I'm shooting JSB 16gr @ 935 ft/sec & 18gr @ 875 ft/sec.

Barrel length = 650mm.

I redid the crown as I was not satisfied how it arrived.



Anyone else tried / noticed this ? I plan to continue shooting it for now without cleaning and see where it get me.......
 
I should add ....

- All pellets straight from the tin
- Most of them are stacked on top of each other but 10-15mm would be the CTC of the total group
- Even when there is some wind around I don't try and "read" the wind. My point of aim always the same. POI might shift due to wind.
- I'm shooting of the bench
 
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The Benchmark barrels that I've dealt with are very tight, have a steep taper, and a bore finish more suitable for powder burners. All qualities that lead to barrel fouling. I find that after a thorough barrel cleaning my velocity will be about 30fps slow. For the first 80 shots the velocity will slowly rise again until it will finally plateau. Somewhere between shot 20 and 40 it will be super accurate but before and after not so.
I did fire lap mine after the worlds and it helped but didn't cure it.
It is difficult to hold a tight extreme spread with my BM barrels under the 20fpe level.
I don't use my BM barrels anymore and instead prefer my Kreigers. The Kriegers have a properly sized bore/groove, milder taper but the finish is still rough. They do respond well to fire lapping. Mark N shot a 748 51X outside with his Kreiger at the North East regional last month.
Dan
 
Dan, thanks for the comments. See some of my own below.

DanB said:
The Benchmark barrels that I've dealt with are very tight, (I took +/- 30mm off the front when I redid the crown)

have a steep taper (can confirm this)

and a bore finish more suitable for powder burners. (Confirm) All qualities that lead to barrel fouling.

I find that after a thorough barrel cleaning my velocity will be about 30fps slow. For the first 80 shots the velocity will slowly rise again until it will finally plateau. (I found the same but continue to shoot. Now up to +/- 900 pellets)


Somewhere between shot 20 and 40 it will be super accurate but before and after not so.
I did fire lap mine after the worlds and it helped but didn't cure it.


It is difficult to hold a tight extreme spread with my BM barrels under the 20fpe level. (I will confirm this again now that I've done a lot of shooting)


I don't use my BM barrels anymore and instead prefer my Kreigers. The Kriegers have a properly sized bore/groove, milder taper but the finish is still rough. They do respond well to fire lapping. Mark N shot a 748 51X outside with his Kreiger at the North East regional last month.
Dan
Click to expand...
 
My last CF Krieger barrel

is very rough. I didn't bore scope it before I sent it off to be fitted and apparently the fitter didn't scope it either. I actually think this barrel was not lapped after it was cut. It seems to shoot better the more it is used and should probably be lapped a bit, FWIW.

Pete
 
Dan, tested my BM over the chrony this afternoon. Did not had much time so only did 2 x 10 shot strings.

With 16gr AA, Ave 903 (I thought it was higher !), ES 5.71

With 18gr AA, Ave 845, ES 9.86
 
Those are good numbers.
Dan

Wannebe said:
Dan, tested my BM over the chrony this afternoon. Did not had much time so only did 2 x 10 shot strings.

With 16gr AA, Ave 903 (I thought it was higher !), ES 5.71

With 18gr AA, Ave 845, ES 9.86
Click to expand...
 
Increased the speed with the 18gr today to Ave 920 ft/sec ..... ES 5.23 over 10 shots (all I had time for)

This is not a competition rifle so more power is better. I think I will leave it there for the moment and see how we get on.
 
Now up to +/ 1500 shots .... accuracy still constant .... for now we keep going ....
 
Dan, I think the barrel build up lead only up to a point and then stay +/- the same. I will need to push a pellet through and check how it come out.
 
Every time I've pushed a pellet though the bore of a dirty BM barrel it plows lead from the bore and it accumulates around the head of the pellet. The flakes are remarkably large.
Dan

Wannebe said:
Dan, I think the barrel build up lead only up to a point and then stay +/- the same. I will need to push a pellet through and check how it come out.
Click to expand...
 
DanB said:
Every time I've pushed a pellet though the bore of a dirty BM barrel it plows lead from the bore and it accumulates around the head of the pellet. The flakes are remarkably large.
Dan
Click to expand...

Dan, I found the same ... but now I'm confused ..... I would think that those flakes should get pushed out when one shoot a pellet also but I don't think it happens ..... I have a silencer fitted to my rifle with 3 x chambers and I see absolutely zero lead deposits in the silencer ???

Maybe at speed the pellet don't collect the lead but rather slide over it ???

I also shot the rifle at 100m (outdoors) yesterday .... out of the shoulder off the bi-pod. Couldn't believe the accuracy and there was some wind around also .....
 
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