Berger 6mm 108gr BT copper problem?

[JustinP]

Hey guys

Have recently tried the Berger 108gr BT in my 6XC. Accuracy is good but I end up with significant copper fouling.

When I use the Lapua 105gr Scenar - I don't have this issue at all. Virtually no copper fouling. Same with Sierra 107 SMK

Barrel is a Krieger 1 in 7.5" twist. Inspection with the borescope indicates no internal problem.

Anyone else had this problem? The Bergers use J4 jackets, I think. Are these known for being soft?

Puzzling...

 

[GermanS1]

I shoot Berger 105's and 108's in various 6BR barrels and two 6XC barrels,115's there too) and have not noticed any particularly heavy copper fouling from Bergers. I have shot the Lapua 105 now and then and it doesn't seem to foul any more or less. FWIW...

 

[JustinP]

Thanks German. All a bit of a conundrum really - maybe something to do with this particular barrel...

 

[GermanS1]

Justin, tomorrow I'm shooting a 1000 yard match with Sierra 107's in the 6XC, loaded to 3300 fps with Reloder 17. The barrel has about 1400 rounds, we'll see how it looks,fouling) after 70 rounds.

I wish I had the Bergers loaded for this test, but this is leftover ammo from when I initially tested the RL 17 in the summer. This is actually going to be my first chance to shoot it at 1000 yd. since our season is just beginning. I shot one 500 yard match with it in August or so and shot a 600-39X so I think the load will be fine. I hate going into a match with a new load though - I did that today at 600 with a new load for the 30-06 and it wasn't as good as my old load... :^,

 

[JustinP]

German

Will be interested to hear the results. I only run my 108s and 105s at 2900fps, so only a medium load. RL-17 isn't available in Australia, unfortunately. I use 38.4gr of H4350,ADI AR2209 as it is called down here)to run it.

I don't get the fouling issue. It has never been a problem previously... only takes about 20 rounds.

 

[GermanS1]

Justin, I shot my match yesterday with two 6XC rifles. In the first one, I shot 48 rounds of Berger 115's at 2950,using H4831sc) and in the other I shot 24 rounds of Sierra 107's at 3300,using RL 17).

I just finished cleaning both rifles, I examined both through the borescope before and during the cleaning process. I would say that the one with the fast load and Sierras had a tiny bit more copper wash near the muzzle than the Berger despite twice the rounds fired with the Bergers - of course, the Sierras were being fired with a faster load so that is not a strange outcome. However, I'm looking for fine distinctions here, neither was fouled in any manner that I would consider abnormal or objectionable, just the usual very light wash of copper near the muzzle where bullets are going their fastest.

While this is far from beng any sort of rigorous test, I would say, at a minimum, that I didn't detect any meaningful difference between the two type of bullets in terms of copper fouling in this very informal test.

 

[JustinP]

Very interesting, German

I'll have to do some re-testing with other projectiles to see if there are any differences.

Out of interest, what is your H4381SC load? I've tried it through my 6XC but the barrel is only 26" and quickload gave me an indication of a fair amount of unburnt powder. In the absence of RL-17, I'd like to try it again though.

Cheers

Justin