I've been shooting a .308 bolt gun in a Spring 200 yard offhand league for about 15 years. I usually clean the rifle after every 3 practices/matches, which is 66 rounds. I frequently can't clean my rifle until hours after I've shot, and sometimes not until days or weeks after, depending on the chaos level at home.

I've shot a lot of Lake City Match ammo (when I could get it) and reloads with IMR-4064. A year or so ago, I decided to try Vihtavuori N-135 because it's supposed to meter a little more uniformly. It seems to meter well and shoots just fine, and for the most part I haven't noticed any big differences.

At the end of last season, I couldn't clean my rifle for a couple weeks, by which time the powder fouling has fossilized in the barrel. I eventually ended up using JB bore paste to clean the last of it out. I didn't suspect the powder at the time, because I had pretty much the same issue with my wife's AR-15, which had ~150 rounds of Federal XM193 through it. I've got a SS Krieger barrel that was lightly fire lapped when new, and the bore is like a mirror when it's clean. It usually doesn't take a lot of work to get it to shine.

Yesterday I shot some of the N-135 reloads and cleaned the barrel a couple hours after firing. This time I had the same problem with heavy fouling stuck in the barrel. It starts at the chamber, and fades out as you get about half to a third of the way down the bore. I don't ever recall having anywhere near this much trouble with the LC Match ammo or my IMR-4064 loads. The only other possible difference is that I'm using BoreTech Eliminator, rather than Shooters Choice, but from the stain on my patches, I'd say the BoreTech stuff works better than Shooters Choice.

I'm beginning to suspect the residue from the N-135 may be a lot tougher or faster "setting" than the residue from IMR-4064. Before I switch powder again, I was wondering if anyone else had any similar problems, or had any ideas. I can try Shooters Choice again, but I don't like mixing solvents during a cleaning session, so that will have to wait a week until the league is over. I hope to have a practice session & a match through it by then, or another 44 rounds.

One other factor is that these aren't full power loads. I've read other threads where people have had excess fouling with light loads. However, the powder charge I'm using in N-135 is pretty much in the middle of the specified range for the bullet weight. My IMR loads were possibly a little faster, but not by much.

Thanks for any comments or suggestions!

DaGwhite

Thats funny I use VV 135 in my Viper drop port LV it has a SS Krieger barrel also. I've never experienced what your taking about here. My Viper is the easiest fastest gun to clean I have ever owned.

I have shot VV 135 and V140.It has been some of the cleanest powders I have used.Never had the issues with Fouling'

Regards , Mike

quote:

Originally posted by DaGwhite:

One other factor is that these aren't full power loads. I've read other threads where people have had excess fouling with light loads.

I have never used Vihtavuori powder so I cannot comment on it.

I have used Varget in low-power loads, and it produced the dirtiest cases I've ever seen. So, yes, it does seem that at least some powders produce heavy fouling when used in reduced power loads.

Might want to try RL-15
...tj3006

I have used VV N560 quite a bit and experienced no abnormal cleaning issues. However, my best accuraciy loads are 2 grains below the maximum load, so I can't comment on reduced loads with VV powders...Rusty.

I have used N110, N133 and N140. They all seemed to be quite clean burning and precise.

Vihta is basically the 'industry standard' over here, also due to their good documentation and customer support.