I was at the range yesterday with my 18" precision rifle doing some hunting load development with Barnes 70gr TAC-X loads over Varget. I began the day with a copper free, clean barrel using M-Pro 7 Copper Remover and a light oil with FireClean. After a few shots of my 77gr SMK/Varget load to lightly foul the barrel, I was getting great groups of .5-.75 moa with my Barnes/Varget load. Then I moved onto a 77gr SMK/TAC load. Starting off it was doing great, but as the day went on, no matter what I did, my groups got larger and larger (1.5-2 moa). Even Mk262 was around 1.25 moa as my last group of the day, but this rifle has never really liked that load as much as my Varget load. The only thing I could think it was a result of was copper fouling… I’ve always been under the impression that copper fouling (some, not a lot) is good for repeatable accuracy. I’ve even heard of some precision guys not cleaning their barrels for 500 or so rounds… I don’t have a problem cleaning my gun, I like my guns clean, but I don’t want to have to remove copper every 100 rounds…
I don’t mean to toot my own horn, but I seriously doubt it was me. I can understand 1 or 2 flyers, but all five shots…
FWIW, I may have shot 100-110 rounds through this particular gun yesterday. I have a limited amount of these expensive Barnes bullets, so I’m trying to narrow this down quickly before wasting more ammo.
I know every rifle is different, but what are your thoughts/experiences?
I get that from some barrels when switching between Barnes and jacketed bullets. Accuracy comes back after a thorough copper cleaning.
Some barrels tolerate it, some don’t. To a lesser extent, this can happen when switching powders too.
We’ve gone through this exact same deal on a few gas guns. I’m 90% sure it’s not copper fouling. But you can easily check with some Boretech Cu2. The patch coloring will tell you the amount of fouling you have. I use this to clean some of my copper fouling out every so often. I don’t clean to perfection… the logic being that I don’t have to refoul the barrel into its groove.
But anyway… I can only tell you that we were simply convinced that the ammo wasn’t right… the primers weren’t the same lot, etc. But the bottom line was that it was just us on the gun.
I pulled regular production ammo, busted out the chrono, the bolt gun, and the mechanical rest. The ammo performed in all tests and every group had single digit S.D.s
We went as far as swapping barrels on an AR to get back to half MOA… But it all boiled down to lazy and sloppy rifle habits as far as I can tell. I can’t even begin to tell you how similar your question is to what we went through ourselves.
Most recently, I had Pappabear spotting as I shot an 8 or 10 round group… and he could see the last 6 or 7 shots just stacking. As soon as I quit Tarding on the gun and actually settled in, the ammo and gun did their thing.
I was experimenting with Barnes bullets a couple of years ago. The Barnes tech told me for best results with their bullets the bore had to be completely cleaned of previous copper fouling. I used KG12 copper solvent which gets all of the copper out (cleaner than some may want). He also said some barrels needed to be cleaned every twenty rounds or so to maintain best accuracy.
I did experience the deteriorating accuracy as I fired more rounds in three different ARs. One of the ARs with a good quality, free floated barrel that maintained 1.5-2 MOA with conventional ammo opened up from about 2 MOA to 5-6 MOA after about 15 rds of TSX. These were 5rd groups at 100yds off a rest. Each group was progressively worse. The other two rifles showed the same tendency but not nearly so extreme.
In addition, I found I had to clean all of the Barnes fouling out to get back normal accuracy with good quality conventional bullets. I decided Barnes bullets were not worth the trouble. I guess they were originally developed for hunting where only a few rounds are fired between cleanings.
I have some barrels that won’t tolerate the Barnes at all, others will go hundreds of rounds until accuracy degrades to the point that I’ll remove the copper fouling.
I’m wondering if maybe the Barnes bullets don’t like chrome lined barrels. A limited number of shots were pretty accurate in my 243 Model 70 lightweight bolt gun. Didn’t fire enough to be sure. I just don’t like the idea of having to clean between ammo types.
I contemplated the switch to solids when they hit the long range market. Amazing B.C.'s and flight characteristics. I ultimately decided against the change over due to the previously stated reasons. Accuracy is hard to sustain due to blow by and copper fouling. The stuff I read at the time (wouldn’t be able to find it if asked) said you either got powder fouling from bullet not sealing like a traditional bullet when fired, or, you got copper fouling from a bullet that had larger driving bands trying to seal the bore. At distance they were only getting maybe 10 accurate shots before needing a clean.
That is more correct of the bullets from past than current ones of the past few years. Just like anything else in loading rounds, some things work in some guns, in others they do not.
Hmm, interesting. I don’t plan to shoot more than a few rounds of the Barnes bullets at any one time since these are solely for hog and possibly deer hunting. So I’m not too worried about a high volume of rounds and copper fouling.
This issue never occurred with my 77gr SMK’s, only the Barnes bullets (the only two bullets that have been through this barrel). If I’m running a lot of rounds thought it, the SMK’s definitely get the call. I know Barnes recommends a clean bore when testing, so when I get back to the load development I suppose I’ll remove copper after every 5 shot group just for extra assurance. As some have mentioned, maybe the grooves and solid copper construction make a difference regarding copper fouling?