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Dirty Barrel Experiments

orkan

Primal Rights, Inc.
Banned !
Minuteman
  • Oct 27, 2008
    4,268
    3,996
    South Dakota, USA
    www.primalrights.com
    Well I finally ran into some problems with the original "dirty" 6BR. This rifle has been one of two rifles which were the basis of an experiment I have been running on the behavior of barrels which are not cleaned for extended round counts. Load workups were done after 250-300 rounds had been fired on each, to get the bore heavily fouled and then get a very tuned node established... and then see how long it takes to come out of it.

    PzFyoiRh.jpg


    The barrel has just over 2500 rounds total now. I had 1530 rounds since it was last cleaned, and it pressured up bad, and quick. I had 100 rounds loaded up all in the same batch, and pressure started about 30 rounds into it, so it presented a nice opportunity. In the name of science, I sacrificed a few pieces of brass to the cause. Once it pressured, I tried some things to make double sure it was the bore condition that was causing it and not some other variable. I had been able to run the same loads during the entire "fouled" condition of this barrel, so after about 300rnds to foul in, my loads have not needed to change across multiple bullet types.

    When I say it started to pressure, I mean it was violently demolishing brass. From the onset of pressure on the left, to where it ended up when I stopped on the right. The things I do in the name of science... :rolleyes:
    1YuP6nal.jpg


    The following was done, with no positive effect:
    Removed the suppressor.
    Cleaned the chamber.
    Cleaned the brake.
    Seated bullets deeper 5 thousandths (making sure no cold weld)
    Full inspection of bolt, trigger, and action components.
    Pushed a dry patch down the barrel.

    Rounds were fired after each step to check each variable independently. No change was observed, as pressure signs on the brass were equally high at each step. Final step was to clean the bore!

    When it first started pressuring up, I put it on paper at 100yds and fired two 5-shot groups. The top group was first, then it started hitting pressure bad, and the second group is on the bottom. Obviously went fully haywire.
    PZ7uMXPl.jpg


    Here's a short video showing the bore condition at the time of cleaning, with roughly 1564 rounds since the previous cleaning.


    I went at the barrel with wipe-out patch-out and accelerator, and after a few cycles with heavy brushing... I went to Flitz polish and used some aggressive pellets and viciously polished the bore. I could have kept at that for an hour and still not got it all the way clean I think.
    Here's a video of where I ended up.


    After cleaning I fired 5 rounds on steel, just to settle it in a bit. Then I fired a couple 5 shot groups at 100yds. First one was a bit wild... as I suspect the bore wasn't quite settled in yet. Second one started to look much better.
    1qYZ0ZJl.jpg


    TE72UWbl.jpg


    While I understand none of this will be a huge revelation... its still nice to have some quantifiable and observable results with a rifle that has had a good barrel log. The same load that has always run well in this rifle, ran well after I cleaned it up. At 2500rnds, the barrel is still performing acceptably. It's also noteworthy that the rifle went right back to its previous zero once cleaned. The remaining 20 rounds which were fired after cleaning, exhibited no adverse pressure. This Benchmark barrel has certainly exhibited some excellent stability. It will be interesting to see how it behaves going forward.
     
    That’s a lot of rounds since cleaning for sure.
    I’ve never gone that far with my 260.
    I actually clean a bit more often than I used to, mainly to avoid having to scrub the crap out of it because scrubbing a barrel is a pain in the ass.
     
    I have some chrono numbers floating around for it... I just haven't really compiled them. It was very stable at distance, and has tracked click for click across this 1500+ rounds of barrel life.

    I was curious to see if your ES stayed within a acceptable range throughout , sounds like it did
     
    Cool thanks for putting that together. Out of curiosity what barrel and what kind of jump are you running?

    I’m a non cleaning kinda guy and I think 1300 or so as far as I have gone (I clean if it gets rained or snowed on) I do however clean the chamber with a .410 or a .45 mop every 200 rounds or so. If I don’t I get ejector swipes.
     
    Good data thank you. Do you like the Flitz better then Iosso for removing stubborn carbon?
     
    Carbon fouling.

    In the barrels this community typically uses for precision/LR shooting copper fouling is a non-issue. It's there and occasionally leaves some copper streaks in the bore from vaporized jacket material. Not a big deal. The stuff is atoms thick and doesn't really build up over time.

    Carbon in the throat builds up and causes problems. In a 6.5 PRC you can have it go from spotless to dangerous in 100-200 rounds. In some cartridges it can be 500, in some it can be more. Opinions differ but my experience is that the longer you let the stuff sit, cake, and bake, the harder it is and the longer it takes for shit to settle back in once you clean it. Brushes do not hurt your barrel, rods do. Don't be afraid to hit carbon with a bronze brush. Leave the stainless brushes alone.

    Iosso and other mild abrasive cleaners in the throat of well used barrels seems to bring them back in line for a while. I wouldn't use it unless there's an accuracy problem or stubborn carbon problem that won't go away otherwise.

    Barrels that aren't toasted and are cleaned regularly (every 100-300 rounds) come back in after 1-3 rounds. Barrels that are getting long in the tooth can take 5-15 rounds. Barrels that you let get nasty dirty before you clean are typically the ones that take longer to "settle back in". YMMV.
     
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    Good data thank you. Do you like the Flitz better then Iosso for removing stubborn carbon?
    I haven't used Iosso in this capacity. I used Flitz on my dies once upon a time, and decided to try it on barrels with VFG pellets... worked great! So I stuck with it for stubborn fouling.

    Out of curiosity what barrel and what kind of jump are you running?
    Benchmark barrel. Jump largely depends on what load I'm running. With the 95's I'm about 50 thousandths off if memory serves. Once I find the lands with a certain bullet... I pretty much ignore the "jump" aspect from there on.
     
    This is good info IMO. Maybe it’s not such a good idea to wait to clean until accuracy falls off. Maybe a cleaning regime of every 500-1000 rounds might not be such a bad thing.
     
    I think waiting to clean until accuracy falls off is probably just fine, but you'll want to be looking for a subtle change. Not a large one. If it starts opening up by a tenth or more, give it the treatment. This rifle definitely shot better in the sub-500rnd territory than it did in the 1000rnd territory.
     
    Thanks for posting this. Informative finding that will come up when people search this type of thing for years to come. I’ve never taken it to this extent, but it mirrors what I’ve also observed. Start to get a little pressure or groups consistently open up 1/10 mil, when nothing else has changed, probably needs a little scrubbing. Now I prophylactically clean the carbon out every 100-200 rounds. Shoot a couple for it to settle back in and keep going.
     
    Looking at the video of the bore, it sure looks like the lands are rough. The grooves look smooth. How long did it take you to get to your round count?
     
    Carbon ring will do that. Had the pressure spikes you experienced as well only about 250 rounds in since last cleaning (although I never attacked the throat to clean out carbon ring)
    I was getting velocity increases of about 100 fps on my established load of 41.4 gr. of RL16 in GWT brass (6.5CM) 26 inch barrel was yielding 2930 fps and I knew something was wrong. Tested my scale (FX120), charge weights, and nothing had changed.
    Bought a Teslong and saw the carbon ring and decided to attack it. Afterwards, everything settled back down to normal.
    Carbon fouling is a thing, and I now clean the barrel out every 100-150 rounds, no problems since.
     
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