Copper fouling note

[Brad Y]

On a recent thread it was discussed that barrel block style rifles may have a 'squeezing' effect on a projectile as it travels down the bore. After rebuilding my rifle, I said I would post up on what I found.

Using 180vld's moly coated, my previous set up still coppered up. Not to the point where I couldnt use it within a day, but after a few hours soak with hoppes, it still needed boretech or sweets to clean up the final streaks of copper. Now the rifle has no barrel block, Im pleased to inform that a 1hr soak of hoppes has shown no copper left in the barrel. However, I will emphasise that this barrel has been rechambered also. Maybe there was a rough patch on the throat that I didnt see from the last chamber, but now its looking very good and cleans up well. Im actually planning on not doing any more moly coating- though it will mean re working the powder charge.

[Frank Green]

Brad Y, Maybe you had a rough spot in the throat that was causing the fouling the first time and maybe not.

After rechambering the barrel are you using the same lot of bullets or are they a different lot of bullets? The bullets can vary from lot to lot and foul differently/cause copper fouling issues etc...

Yes I would agree the barrel block can be tightened to much and cause a bore restriction even though I have no experience with barrel blocks myself but there is another thread on this forum about straight/parallel barrels vs. contoured barrels and also they talk about tuners.

Using a tuner or a muzzle brake you can easily tighten them to much and will cause the bore to constrict/effect the bore sizes etc...and the last place you want this to happen is right at the muzzles crown as it will cause accuracy problems.

Seen plenty of rifles were the muzzle brake or flash hider was tightened to much and it cause accuracy issues. Service/match rifles (M14's, M16's etc...) where the flash hider or flash hider nut was tightened to much as well and it will distort the bore. Same goes with the M14's figure eight nut back at the gas cylinder. This is right in the middle of the barrel. This nut can be tightened to much and it will actually bow/bend the barrel up!

Also the length of the barrel can cause fouling issues as well. Going longer than 30" sometimes will cause copper fouling issues but not all the time.

Later, Frank
Bartlein Barrels

[RDavies]

Brad, my new gun will have a similar style clamped barrel block to what you were using, so bore constriction was something I am concerned with. I wonder if there is a general rule as to what torque on the clamp screws will provide enough security in the barrel without constricting the bore?

[Frank Green]

I've never had a need for a rifle with a barrel block so that's why no use/experience with one. Have a local guy that has one for a 1000k bench gun. I do know that he had issues with how tight he had the screws on the barrel block and it can cause harmonic issues with how tight or loose they were and it cause accuracy issues.

I feel it's a big variable and if you are going to run a barrel block you will have to play with the torque specs. to get the most out of it.

Just my opinion.

Later, Frank

[AlanF]

The 5 bolt pairs of my steel V-clamp are are just nipped up lightly with a T Handle hex key - no torque wrench. Initially, I tightened them up tighter, but even with the light settings, the barrel never moves. The top plate of my clamp has been "sliced" into sections, one for each pair of bolts. I think this probably increases the grip strength (bolts may "lean" backwards minutely as barrel moves). Earlier I suspected some bore constriction, so used Iosso in that area, and continue to do so, but only occasionally.

Alan

[Brad Y]

Thanks for all the replies.

Another 13 shots last night, this time with naked bullets has shown some copper, but not enough to stay with moly coating. Same as Alan, a small amount of iosso paste occasionally to keep the throat smooth both on the lands and in grooves. Have been caught before with hard crackly carbon ripping copper off the jackets.

While I dont always think the block was a restriction (it worked superbly in a 260 improved) I feel that if you are going to use them, you need to make sure the barrel profile is 100% the same consistenly and that yes you dont screw it down with huge amounts of torque. For an F class rifle that I plan to change barrels on during a shoot, the regular method of barrel into action and bedded with either pillars and bedding compound, or a V block, is alot more user friendly. With the barrel block getting everything right in that setup it would take me about half an hour to change a barrel. Sometimes in a prize shoot that half hour was too tight for comfort- especially if I was last down in one range then first down the next.

In a 1000yd HG situation where you arent changing barrels, I would definitely favour this type of method.

[AlanF]

Brad,

My first barrel clamp was a pain with changing barrels, but I now have a clamp for each barrel so changing time is the same as for a conventional setup.

Alan

[Brad Y]

Alan

That was the plan but I think it was mr deehan who bought it off me. Im back with a conventional setup, and enjoying it. Will be shooting both barrels sunday. If I can confirm the loads in both, they will be put away and I will get to play with the 6mm again finally.