Bartlein New Barrel Material 400MODBB
- Thread starter Frank Green
- Start date
Biggest thing is keeping up with it and not letting the fouling/barrel get away from you.
I’m in the camp of not letting it go past a 100ish rounds in between cleanings.
If I shot a match today and put 70 rounds on it… I’m cleaning it that night before putting another 70 more rounds on it the next day.
You let it away and you can be chasing your tail.
Some calibers are easier on barrels than others… 6CM is not easy on the sticks.
I'm with Frank, if I shot 50+ I'd clean it. If it's just a 30 round trip I'd go two trips like that and then clean. Seems good so far on a .308, YMMV.
Indeed and unfortunately I'm pretty hard on my guns with constant 10 and 12 round strings because I like to compete and I use whatever powder I can find.
I hate to be so hard on my bartleins but I also like to win lol.
ETA sorry I didn't see this was a mod BB
my comments have all been about regular bartlein stainless steel, whoops. haven't gotten around to ordering the mod bb yet, just wanted to be clear about that.
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I'm near the end of my first 400MODBB barrel in 6CM. With my last 2 (regular) barrels in 6 Creed, the barrels would slow down around 1000-1100 rounds. They would then continue to shoot well for another 500-600 rounds or so, and then either slow down more or start to throw fliers. So basically I got about 1500 good rounds out of them. My current barrel started out the same, but did not slow down until just after 1500 rounds. I now have just under 2200 rounds on it. My best groups are still tight, but my perception is that overall my groups are starting to open up a bit. And I'm seeing more vertical issues in the last couple hundred rounds, hard to say if that is the barrel or the conditions. But the new barrel material has definitely extended the useful life for this caliber. This is in a 28" barrel, with ave around 3050fps at its peak, currently running around 3020fps. This is hooting a mix of PRS style matches and our club long range matches (50 shots in an hour or so, typically 3 groups of 3 at a time in maybe 5 minutes).
understood, that still may be remarkably good barrel life to hold up strong for 2k rounds with a rough schedule and charge and such. which bullet again?
fwiw my statements are pertaining to 115dtacs and h4350 mostly.
I just found out about 400BB last night. A customer supplied one and they say it feels different to cut....that is (or was for me) an understatement.
I would love to hear from some other smiths, their experience on cutting these (especially on a manual machine).
I will say this was a 338LM chamber which of course is going to take longer but this was way different. Actually worried it may have hurt the reamer a little bit. This is a brand new JGS HSS reamer. Turning at @ 100 rpm. It made good chips the whole time, just took a significant amount more pressure to cut and that made me uncomfortable having never used these. I didn't notice a difference cutting the tenon thread or the cone on the chamber face (it's for a BAT CT).
I love bartlein barrels and have cut many in 416.
I really hope this thing gets the longer life like they say.
I would love to hear from some other smiths, their experience on cutting these (especially on a manual machine).
I will say this was a 338LM chamber which of course is going to take longer but this was way different. Actually worried it may have hurt the reamer a little bit. This is a brand new JGS HSS reamer. Turning at @ 100 rpm. It made good chips the whole time, just took a significant amount more pressure to cut and that made me uncomfortable having never used these. I didn't notice a difference cutting the tenon thread or the cone on the chamber face (it's for a BAT CT).
I love bartlein barrels and have cut many in 416.
I really hope this thing gets the longer life like they say.
Bushing fit great. It started cutting fine but once it got past the shoulder it just got tougher and tougher.
Shouldn't take "significantly" more pressure. Check your bushing fitment and possible barrel alignment. HSS reamers will try and flex to follow misalignment. You said you had good chips......but you may have ran into some work hardening. Did the barrel feel warm?
Lots of real estate on 338lm.......I cut rpm down to about 80.
I think your experience is coming from something other than the barrel material.
Ern
Lots of real estate on 338lm.......I cut rpm down to about 80.
I think your experience is coming from something other than the barrel material.
Ern
It got very warm. I had stop a bunch of times to let it cool down. I just cut another 6.5 creedmoor yesterday....like butter compared the BB steel.
When you say shouldn't take much more pressure, are you running manual or CNC? I just wonder if you are referring to things like spindle load vs sense of feel.
I think as others have said it may have started to work harden. There were points where it wasn't so bad and then harder again. you could literally feel it change. But then as you said perhaps the bushing size was on the edge of tolerance and that was changing but I had never seen that before. But I haven't cut thousands of barrels....yet
Manual.
If there wasn't any side loading on the reamer......I bet you were getting work hardenening.
Slow the rpm on big hss reamers. Plenty of fluid. Don't let the reamer dwell and avoid slow feed minor passes.
IF you have that issues again. I found that sanding the chamber surface with lubed 400grit will break through the hard surface...... just make sure you get ALL the grit out. Flush/clean until you are confident its gone then do it a couple more times.
Hope this helps.
Ern
I'd go try that same reamer in an offcut of standard 416 and see if it's the reamer.
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JGS reamer, second chamber it has ever cut so not likely. I don't have another 338 blank on hand to try at the moment. But It's not impossible it could be the reamer.
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