-
Having trouble using the site?
Contact support
Gunsmithing WIP: 338 Big Baer Heavy Tactical/XLR Hunter
- Thread starter LRI
- Start date
Looks like a great foundation – is it engraved “228BIGBAER”(two two eight?) just in front of the barrel tennon though?
I'm positive is says 338....
Keep us updated Chad, that looks like a hell of a lot of fun.
t
Here's the latest on this pig.
Spare barrel, he's gonna need it!
2.4 ULTACH Cheek Hardware:
Rotary broached 6AL-4V pins setup for a 5/32 allen key. -FUN!
408 TAC Stiller action. What a beast!
Spare barrel, he's gonna need it!
2.4 ULTACH Cheek Hardware:
Rotary broached 6AL-4V pins setup for a 5/32 allen key. -FUN!
408 TAC Stiller action. What a beast!
Now that the rifle's just about wrapped up (just need to mount the glass) were onto some tooling work. The die blanks from Newlon arrived yesterday morning. Now for chambering them up and getting them sent off for heat treating and carbon nitriding. Got some extras for an ongoing project were about to debut. . .
Just wrapped up the seater die.
I elected to use the larger (less common) 1.25" OD die blanks for this cartridge. Just made sense to me to have a bigger cushion with the wall thickness to avoid the risk of the die ever cracking. The Big Baer uses a .625" OD rim so a 7/8" standard die is getting pretty thin.
The length of the cartridge presented some challenges for Newlon as they aren't making these dies in any quantity anymore. The big dies just never caught on very well. Because of this his tooling inventory wasn't really setup for these big buggers. To save some time/money I just had him take care of the OD profile and fit the bore where the micrometer head goes. We decided to drill the pilot hole here as I have the setup already ready to go.
I started by indicating the blank to spindle center. Once done with that I drilled a small pilot hole about .750" deep. Then I enlarged the hole with a single point boring bar to -.0005" of the drill. (7.4mm) I went as far as I could with the boring bar, around .625". This way I had over 2x the drill diameter supported when it started drilling the full diameter of the tool. This goes a long way towards ensuring the drills stay on center and don't wander out into left field. A 4" hole depth isn't as easy as it might seem. I went with a solid carbide, parabolic drill with through coolant. This way chip evacuation was a non issue and I could make the hole in one pass. No pecking required. Pecking with carbide is dicey when working with tool steels. Even with coolant one runs the risk of work hardening the surface of the part. Then the drill has to chew through that to get to unmolested material. Keeping the tool engaged the whole time helps to ensure the cutting edge stays close enough to the thermal wave that the hardness doesn't change. This is important both for tool life and to manage the material condition once you start reaming. Hard spots suck!
Once drilled, then we chase the hole to .330 with a simple chucking reamer. This is so the pilot has something to follow.
Then onto chambering. Our reamers are now all solid carbide and ground to very specific cutter geometries. It allows us to cut chambers very quickly, avoid many of the challenges that HSS cutters face, and improve the surface finish/location accuracy of the feature. Took a long time to sort this out, but after a year of it were sold on the process.
So, the die is chambered and qualified. Now to make it work. The bullet is .338, the pilot hole is still .330". Bullet no fitty too well. I could have reamed it but I want a slip fit on that projectile with as much of the die supporting the bearing surface as possible. This helps to ensure concentric/parallel purchase by the case neck. Honing the bore to a taper free slip fit is pretty quick work on a Sunnen Hone. So, that's what I did. Machine is a messy job, but its the best answer for this stuff.
From here were pretty much done with all the "heavy lifting" work on this. Now its just a matter of washing it up and seeing how we did.
I elected to use the larger (less common) 1.25" OD die blanks for this cartridge. Just made sense to me to have a bigger cushion with the wall thickness to avoid the risk of the die ever cracking. The Big Baer uses a .625" OD rim so a 7/8" standard die is getting pretty thin.
The length of the cartridge presented some challenges for Newlon as they aren't making these dies in any quantity anymore. The big dies just never caught on very well. Because of this his tooling inventory wasn't really setup for these big buggers. To save some time/money I just had him take care of the OD profile and fit the bore where the micrometer head goes. We decided to drill the pilot hole here as I have the setup already ready to go.
I started by indicating the blank to spindle center. Once done with that I drilled a small pilot hole about .750" deep. Then I enlarged the hole with a single point boring bar to -.0005" of the drill. (7.4mm) I went as far as I could with the boring bar, around .625". This way I had over 2x the drill diameter supported when it started drilling the full diameter of the tool. This goes a long way towards ensuring the drills stay on center and don't wander out into left field. A 4" hole depth isn't as easy as it might seem. I went with a solid carbide, parabolic drill with through coolant. This way chip evacuation was a non issue and I could make the hole in one pass. No pecking required. Pecking with carbide is dicey when working with tool steels. Even with coolant one runs the risk of work hardening the surface of the part. Then the drill has to chew through that to get to unmolested material. Keeping the tool engaged the whole time helps to ensure the cutting edge stays close enough to the thermal wave that the hardness doesn't change. This is important both for tool life and to manage the material condition once you start reaming. Hard spots suck!
Once drilled, then we chase the hole to .330 with a simple chucking reamer. This is so the pilot has something to follow.
Then onto chambering. Our reamers are now all solid carbide and ground to very specific cutter geometries. It allows us to cut chambers very quickly, avoid many of the challenges that HSS cutters face, and improve the surface finish/location accuracy of the feature. Took a long time to sort this out, but after a year of it were sold on the process.
So, the die is chambered and qualified. Now to make it work. The bullet is .338, the pilot hole is still .330". Bullet no fitty too well. I could have reamed it but I want a slip fit on that projectile with as much of the die supporting the bearing surface as possible. This helps to ensure concentric/parallel purchase by the case neck. Honing the bore to a taper free slip fit is pretty quick work on a Sunnen Hone. So, that's what I did. Machine is a messy job, but its the best answer for this stuff.
From here were pretty much done with all the "heavy lifting" work on this. Now its just a matter of washing it up and seeing how we did.
Just want to clarify something.
In this photo it appears as if something has gone radically wrong. It freaked me out as I was posting the last update so I went back and checked everything. The bore is not out of location. It's just how the glare/shadow/angle the photo was taken appears. There was a drop of mineral spirits from cleaning still clinging up along the neck/bore transition point that didn't help either. Everything is as its supposed to be.
A good thing as having to start over would be the only option and that would suck.
In this photo it appears as if something has gone radically wrong. It freaked me out as I was posting the last update so I went back and checked everything. The bore is not out of location. It's just how the glare/shadow/angle the photo was taken appears. There was a drop of mineral spirits from cleaning still clinging up along the neck/bore transition point that didn't help either. Everything is as its supposed to be.
A good thing as having to start over would be the only option and that would suck.
I've made dies off/on for years. Just when the application required it (wildcats).
LRI has a NEW cartridge that is about to launch. The field testing is all done now. It's just a matter of compiling the load data and getting the tooling made for the ammunition company that's going to produce it.
We have been developing a couple setups to run this bugger. Bolt gun and AR/M4's. Thus far the results are exceeding the expectation which is a good thing. It's a fairly clever setup and one I'm rather proud of. I've never been too big on cartridge stuff as it just seems like every mouse trap possible has been made already.
This one's a little different though. . .
More to come!
C.
Tag. (You've got me curious now...especially when I see "408" stamped on the side...)
Last edited:
