Dirty Barrel Experiments

orkan

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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.
 

jarittenhouse

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Nov 18, 2012
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I echo badthirtyone's sentiments. Thank you for all the very detailed and objective information. It was also comforting to see that a barrel that is not meticulously clean, like I always try to achieve sometimes to my frustration, isn't actually needed.
 

orkan

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I would love to buy that dirty rifle of yours I have talked to TS about building one would save me the wait!
What coincidental timing... I'm looking to sell it to make room for this summer's projects. I literally ran out of slots in my vault, so something has to go. lol
I'd strongly recommend letting me have TS Customs rebarrel it for you first though. Feel free to give me a call if you would like to discuss. 605-554-1911
 

AZShooter

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Dec 12, 2005
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Thanks for sharing your experiment. That is an amazing number of rounds through a bore without cleaning.

I have a 6 BR with Bartlein 5R and am thinking I am cleaning too often!!!!

What was the time period for this test? I see you live in SD. Was rifle stored in a safe with dehumidifier? Just thinking about environmental factors. Even with a 6 BR there would be layers of laid down carbon and jacket materials with potential for humidity reacting to it. Any details are appreciated.
 

orkan

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Thanks for sharing your experiment. That is an amazing number of rounds through a bore without cleaning.

I have a 6 BR with Bartlein 5R and am thinking I am cleaning too often!!!!

What was the time period for this test? I see you live in SD. Was rifle stored in a safe with dehumidifier? Just thinking about environmental factors. Even with a 6 BR there would be layers of laid down carbon and jacket materials with potential for humidity reacting to it. Any details are appreciated.
Testing was performed over a period of roughly 3 years. I wanted the results to more accurately reflect the "average shooter" and their more realistic firing schedule. Hence why I have been doing it with several different rifles... so I don't get the round count too high too quickly. The 6 dasher in this test is coming up on 1400rnds since cleaned, and the .223AI is around 800. (I need to shoot it more)

All rifles were kept in 70° open air or walk-in vault during that time. Avg humidity of probably 40% for the past year and closer to 60% the 2 years prior. I also made double sure to let them sit for extended periods of time without being cleaned. Each winter they'd basically get shelved while I was shooting coyotes with 22 Creedmoor... ;) So they've sat 6 months to nearly a year at a time without being touched. Then I'd take them out and hammer rounds through them to see how they reacted.
 

AZShooter

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Thanks for those details!

Didn't think of this one till just now: did the POI move when first fired after sitting for a period of time? I am remembering that some of my fouled rifles needed a few shots to settle them back down then they were fine.
 

orkan

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Thanks for those details!

Didn't think of this one till just now: did the POI move when first fired after sitting for a period of time? I am remembering that some of my fouled rifles needed a few shots to settle them back down then they were fine.
No, it only shifted when it started hitting pressure.

I recently took a 22BR out that had been sitting for a couple years with only a couple hundred rounds on the barrel and it was as if I just shot it the day before. No shift.
 

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