375 Chey Tac

[@jimmilne19]

It is a pleasure to watch your machining skills, your approach to the work and your tooling and machines. Your running commentary is instructive, clearly recorded and pleasant as well. Thanks for sharing. I look forward to the completion of the muzzle break job.

[@riflesmith1]

Hello Jim. Thank you for the kind words. I will complete the MB install after this chambering is done. Again, thanks............SKI

[@deeremeyer1749]

.408 Chey-Tac with a COL in excess of 4.5" will fit in an AR-30 receiver/magazine lengthwise? That's about 7/8" longer than .338 Lapua. How you pulling that off? Got a pretty significant case diameter difference to deal with too. AR-50s are available in .416 Barrett for the same money ($3300ish MSRP) as an AR-50 in .50 BMG. How does building a custom "AR-30" in .408 CheyTac pencil out compared to buying an off-the-shelf AR-50 chambered for a much better cartridge based on a much better "parent case"?

[@guitarsnguns]

Hey, I like what you are doing and showing. But I have to tell you, you really made me flinch when I saw your hand reaching in several times to grab chips off of a running lathe! Make yourself a chip hook and keep your finger intact. Otherwise, great video.

[@92fsoakcreek]

A tip on Threading/spacing the recoil lug: make a thread relief groove at the end of of the thread, with a depth of the minor diameter. It gives you someplace to stop without gouging at the end. also, Id reduce the spindle speed by !1/2 to give you more time to react. That was pretty fast threading by hand. [I didnt notice a thread-stop to trip the half nut off]. Otherwise a sweet job. :)

[@charlesmcneil618]

Like the video what tool holder and inserts are you using to thread with ?

[@smithandkolar3498]

we typically must thread a barrel with a four jaw chuck to ensure the bore is completely centered to the threads. what is you "trick" to getting away with the three jaw chuck to thread? did you turn a clean up pass with the barrel between centers?

[@riflesmith1]

No trick involved, that is a set thru chuck. I have four points on which to adjust the piece I am holding in a three jaw. If the bore is very off center to the OD, I will use a four jaw on either lathe. Thanks...........SKI

[@deeremeyer1749]

That sounds self-contradictory a few different ways. If the 3-jaw is acceptable because of the "4 points" you shouldn't get unacceptable results. If the bore is off-center to the OD prior to machining then that sounds like a barrel manufacturer problem if you're working with a "blank". If the bore is off-center to the OD post-machining, that sounds like an issue you're not going to fix by then going to a 4-jaw chuck unless there's enough material left to switch to the 4-jaw chuck so you can "re-do" the improper machining the 3-jaw wasn't supposed to allow anyway.

[@yugozastava13]

Where did you get that "compound advance" chart? Appreciated!

[@deeremeyer1749]

That major undercut at the "front" of the barrel thread cut to get rid of a minor "fillet" the recoil lug should have been chamfered to clear is scary as hell. Ever heard of stress risers and how they are set up and cause fractures at sharp edges when an undercut "shaft" is subjected to bending stresses? They're why you never see bearing retention snap rings except outside a bearing and only on shafts where there is no pulley or other bending load outboard of the groove. Where those exist a lock collar is used to keep the shaft from slidding/spinning in the bearing. I can see that barrel snapping right there in that groove someday. And aren't the recoil lug flats supposed to line up with the receiver flats for a "seamless" assembly with the barrel tight? There's no way you got it tightened another 1/8 of a turn or more torquing the barrel into the receiver to get everything lined up. At least not without stressing that undercut barrel and groove a hell of a lot more than they already were. All the way around a pretty scary and "ugly" build to this point. I know lots of machinists and no "gunsmiths" personally even though it seems like everybody who has and can turn on a freaking lathe and can make a KZbin video is a "gunsmith" or "rifle builder" these days. With predictable results. Looks really easy on paper but oddly enough threads have to start and stop at specific points in many "builds" to get all the parts "clocked" correctly, don't they? But its kind of hard to cut those kinds of threads and get them to start and stop where they have to when you're just kicking the lathe on at 500 rpm and letting the compound "do the work". I suppose its just a matter of taking "a few more thou" off the rear barrel "seating surface" to get another turn or whatever you need to get things lined up properly. But then you have to take more off the back of the "chamber" and if you don't get it right in one or two tries, the next thing you know you're back to cutting more threads. You mentioned "advancing the threads" but with the receiver and recoil lug already tight against the barrel more threads aren't going to gain you anything. You have to create clearance somewhere to get the receiver and recoil lug aligned when they're tight against the barrel. Either by removing some material from the face of the receiver or the recoil lug or the rear of the barrel where the recoil lug sits. And if that's an Armalite AR-30 receiver which is must be since its obviously not an AR-50, are you sure its up to the challenge of dealing with .375 CheyTac pressures and loads? More "scary" to think about there. Looks like a "cheap" way to build a "big "rifle and "cheap" shouldn't be combined with "build" of ANY rifle much less a "big" one. Hopefully Armalite's lawyers will find this video if there's ever an "issue" with that "build" and somebody decides to pin the blame for the "issue" on Armalite. Not that Armalite would/will need to prove it didn't "build" the rifle with "issues". In its manufacturing/transfer records whatever serial number is on that receiver sure as hell isn't going to match a .375 CheyTac and "truing" the receiver just put the proof of "modifications" right there in the threads. And is it just me or do those barrel threads "taper" from "larger" to "smaller" as the get further onto the barrel blank? Almost looks like a reversed pipe taper thread and the receiver seems to get "looser" the further on you thread it. Maybe those are "optical illusions".

[@Outland9000]

Noob question... why no cooling fluid? Cheers :-)

[@woodscw50]

thank you bro ! tour of a marine ! life of you use

[@GODWITHUS0712]

is it true that the 375 and 408 che tech parent case is the 505 Gibbs

[@ahmedgmetwally4948]

I'm sorry I lost track of what he is making. What is that again?

[@alanmaughan7968]

Do you still have all your fingers?

[@jimmym40a2]

What action is that? I didnt know Armalite made an action for a Cheytac.

[@AR15shootin]

He is rebarreling an Armalite rifle to 375 Cheytac. I dont recall if he said it was an AR30 or AR50 but my guess is either could handle that cartridge

[@deeremeyer1749]

With a COL in excess of 4.5" you think an AR30 action can "handle that cartridge"?

[@ronaldwells4427]

good, subbed.

[@AJPPP]

@815 IN SOME CASES THATS WHAT SHE SAID HAAAAAA

[@tyj1234able]

most of the video was pretty good, up until you ran your fingers over the thread at 500rpm to check if the threads were sharp.......safety first man