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.
Just gonna add data here.
My smith recently chambered a new barrel for me in a 400MOD; barrel was manufactured in 2024. Compared to my older MOD400 barrels that were I believe manufactured in 2022, he said that:
- Had to slow down the feeding a lot compared to the older lots of 400MOD I had him chamber. Otherwise the chamber at the shoulder would gall
- This was also with a brand new never used 6 Dasher reamer from JGS.
Figured I'd come back and add this as others have stated something similar that wasn't my experience with it at the time.
My smith recently chambered a new barrel for me in a 400MOD; barrel was manufactured in 2024. Compared to my older MOD400 barrels that were I believe manufactured in 2022, he said that:
- Had to slow down the feeding a lot compared to the older lots of 400MOD I had him chamber. Otherwise the chamber at the shoulder would gall
- This was also with a brand new never used 6 Dasher reamer from JGS.
Figured I'd come back and add this as others have stated something similar that wasn't my experience with it at the time.
As far as the reamers go, the reamers are the same with the newer one being sharper. I just figured I’d pass this along since there was discussion of the newer 400MOD barrels being harder to chamber than initial ones.
Thats about all he told me. He has talked about sending the reamer out to get coated to see if that helps lubricity. Just the messenger, not the engineer here. Lol
He has 3 more barrels of mine that are 400MOD, so I’ll report back once he chambers those also for my dasher.
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We're on our 3rd lot of material if not the 4th depending on the diameter of the material. We haven't noticed anything different in how they are chambering etc....
I'll ask a question... who made your reamer?
Also Sig has been the biggest gun user/manufacturer for R&D and builds using the BB material. They are doing all of the finish work (other than us contouring the blanks to they're drawings) and they haven't called with any questions in regards to how a chamber reamer is cutting etc... They've got another order in for some more barrels out of the material. Just got the order last week.
So.....
Later, Frank
I'll ask a question... who made your reamer?
Also Sig has been the biggest gun user/manufacturer for R&D and builds using the BB material. They are doing all of the finish work (other than us contouring the blanks to they're drawings) and they haven't called with any questions in regards to how a chamber reamer is cutting etc... They've got another order in for some more barrels out of the material. Just got the order last week.
So.....
Later, Frank
More info:
This is the 4th MOD400 barrel my smith has chambered for me. The previous 3 were from older lots of 400. I’m just reporting back what my smith had to say in having to slow down a lot when cutting the chamber. He still has 3 more 400 series barrels to chamber for me so I’ll report back once he chambers the next for me. Could have been just that barrel.
This is the 4th MOD400 barrel my smith has chambered for me. The previous 3 were from older lots of 400. I’m just reporting back what my smith had to say in having to slow down a lot when cutting the chamber. He still has 3 more 400 series barrels to chamber for me so I’ll report back once he chambers the next for me. Could have been just that barrel.
No worries bud!
JGS and Manson is who we use. JGS most. For one reason they make carbide reamers where as Manson does not.
When a reamer is brand new... and I don't know how exactly to explain it... but if you will... it can seem to sharp... so it will want to chatter more etc...we see this especially when we start getting into 338caliber and larger caliber reamers. They tend to chatter more when brand new. The larger the caliber... on a standard reamer blank... less support for the flutes. You can see it with smaller caliber reamers also but not as much. After you get a few barrels on the reamer... then they can typically settle down.
Wrap wax paper around the tool. Not making it up. It will calm the tool down till you get a few barrels on it.
First time I told Scotty when he was new and doing chamber work... he was having issues not with one but with two brand new 50bmg reamers. I said... just stop working on the stuff today. It's almost time to go home anyways. I'll bring in wax paper tomorrow and I told him what to do. I went back a few hours later and asked him how it worked? He said... haven't done it yet. His exact words where and I quote "your fuck'd in the head!"
So I showed him how it worked. He was really quiet after that!
Guys like Warner and Tooley etc.. will know this trick. Also sometimes guys will stone the reamers by hand as well.
I am neither an expert knife sharpener nor (obviously) neither a gunsmith, machinist, or barrel maker. So this might be a dumb comparison.
Is doing that wax paper thing to a new reamer (or just using the reamer for a few barrels or stoning it) a little like progressively honing the burr off a freshly ground knife? Because if one doesn’t hone the burr off, the knife feels sorta grabby going through paper*.
Plus the burred edge is more fragile and doesn’t last as long as a basically burr-less edge, but that may be unique to knife sharpening with carbon and stainless steels vs HSS and carbide etc.
Anyway, just asking to increase my knowledge and general curiosity.
*For those who don’t knife sharpen, raising a burr is part of the process of sharpening, not a mistake. The harder part, I find, is reducing that burr to nothing without dulling the edge in the process. You want a perfect V with no microscopic metal flake peeling off it.
Frank
I've found more than once a high flute. A touch or two with an Arkansas stone helps .
Frank, really appreciate this response and I'll forward it to my smith. Again thank you!
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