AllTerra Arms - Precision Rifle Chambering 

That fly gave you the finger. After years of machinist YTbers and hundreds of videos, I understood every word. That demo has been classified 'trade secrets' by others, they skipped 90% of what you showed.

Mitutoyo makes a set of thread pitch mics. I used them for years in the aerospace industry making high end fasteners. (measures 4 decimal places) A set comes with different segments for thread pitch. Other than using Johnson gauges to check your multi leads and single lead with. AKA pitch diameter. I would also get "calibrated set plug" to check your mics. I would also use gage plugs for measuring I.D.s. Nice video.

Used to have a part that I had to hold a very tight tolerance on the angular clocking of a bore at a very shallow angle to the centerline of the outside of the part. Would always do a somewhat similar check as you described for the “north-south” but would use that to set the C axis zero and mill a small flat or groove in the part that I could fit a ground piece of flat stock into, it would make it really easy to indicate into trying to level out a 6 inch bar vs a tiny little scratch mark

Thank you for showing your details. I am a professor and a 'hobby' gunsmith (mechanical engineering) with a decent home machine shop (high-end manual knee mill, lathe, etc...) who is learning from one of the best gunsmiths/shooters in the country. However, it is always nice to see how others do the same thing. Your method seems to be a combination of what Gordy Gritters and Speedy Gonzalez recommend - a hybrid of the two. Not sure why you use the range rod and then indicate the lands/grooves; probably you just want to get it close enough to make the actual indication easier. I just skip the range rod step and do my initial indication off the OD of the barrel. However, I turn my own barrel blanks, so I am pretty comfortable that the OD is fairly concentric with the bore. Still, as you note, the TRUE indication is off the lands and grooves (mostly grooves, as I have been taught). I also have the True Bore alignment system (which is what I think you are using). A question - do you have a spider on the muzzle end of the barrel? That has been my biggest challenge with the True Bore system - I use a spider on the muzzle side and the True Bore is so long that I can't chamber anything shorter than a 26" (finished) barrel (and that is 'just barely'). I am concerned with chatter if holding the barrel only with the True Bore system (despite the 6-jaw) and not using the spider.

At 37:39 you can see one side of the lands is visible basically the length of the freebore. This is an indicator that your throat is NOT smooth and concentric. If you put your long stem indicator back in there at the freebore you will see uneven reaming and hopping.......it tends to get worse in 5R barrels too unless you are very careful and mitigate it accordingly.......just an FYI to you and others.

Fantastic explanations! Thanks for putting this video together.

Very thorough set up and nice attention to detail. Everyone should strive for this level of precision. One question though...When you are checking the alignment of the reamer by sweeping it with the indicator mounted to a magnetic base, how do you compensate for sag or droop in your indicator base. Even with the high quality Noga you are using, when you rotate to the 3:00 or 9:00 position, your base can sag due to gravity and put as much as .002" error into your reading, and as much as .003" when at the 6:00 position. Or does this not make any difference in the accuracy of your set up? In a world where .0001" can matter, it is an honest question. If you don't believe me, attach your indicator base to a rigid bar of steel, touch the contact tip to the bar, zero your dial, then rotate the whole thing in your hands and watch the needle move. It seems crazy, but it happens.

Always learning something new. Thanks for the video. As a fellow 07, I would like to pass some info along and some observations in regards to your reaming process. Coolant used as a cutting oil for your reamers is greatly reducing your reamer tool life. I would recommend having a separate regulated oil pump and catch can to flush using mineral based cutting oils such as Rigid Dark or Hangstefers PC45. The SSG is a must tool for these operations but can easily knock out of alignment during tennon work, threading or simply tool pressure/rpm of spindle. You aint got much support holding on the front of the barrel even with the bore through flush system. All the work you do aligning the bore, your next operation should be to ream the chamber. I would recommend using some sort of barrel support. I have designed spindle barrel collets very similar to airless tires 3D printed from TPU to aid in support. Lmk if you want the files Chamber reamers in HSS should not exceed 200 rpm. Our family has been a tool and die maker for 70+ years. Rule of thumb, HSS, slow carbide- fast. You want the cutting edges to shave, not skim. You should see ribbons for majority of your chambering and slivers only in the last 50 thou as you get to final depth. This keeps the cutting edges sharp and mitigates burning the edges up. Great craftsmanship. Keep it up fellas

Thanks for sharing! 🤘🏻

Its cool to see that there is another bohab machinist out there. I do custom marine hardware, but am looking to build a rifle soon. Great info here. Thank you. Gwar rules!

Incredible!!! Excellent information. Thank you. 🐕

Thanks for showing the setup for concentricity. I am a novice and didn't understand the angular runout procedure. I don't have that amazing chuck, but I can use shims to get the same effect. (a lot more time consuming but possible).

Very interesting. Thanks for sharing.

Well done!!

Fyi ... putting a long tip on a .0001" test indicator makes it read .0005" per mark.

you make the curves inside the barrel. Is it take the shoulder depth only or the whole barrel .

Wow that was pretty cool. With that much precision do you still need to tune your loads for how far off the lands do you typically seat the bullet?

What did you use to make your soft jaws? Looks great

I prefer to lap the lugs in situ, with a trigger and barrel installed, in a stock. When the trigger is installed it is lifting the bolt to the top of the race... and the weight of the barrel (especially on long/heavy f-class rifles) can flex things a little. Long story short, you want to lap it how it will sit in the rifle.

Hey use a automated suviel adjusting chuck for perfecity straight no wavering. M-60

I thought range rods were a thing of the past due to inconsistency? Indicating the barrel with a 5.5" contact on a 0.0001 Interapid is the new hotness. So hot right now.

How much time for one chamber. I think you are using 3 reamers?

I would give ya an A except subjective B usable ends up= a Best-selling plus a view point is inside Crafting 2Ends of Awesome. B is a better-side of experience.

Where’d you get the DOPE Game sticker on your lathe?

Will aAterra rifles ever make to South Africa?

What kind of reamer holder do you use with your CNC? Floating or rigid?

awesome video guys! wish i had one of your rifle, they are sexy af! btw, when you lap the bolt, bettwr do it with the trigger installed, it will put up pressure at the back of the bolt, so if you l'applicazione without the trigger it will probably not be straight when cocked!

Who's range rod is that?

Really? Holding the work with the master jaws?

I still cant get my stupid brain to understand lathe tool offsets for chambering style reamers.

Owe me a pair of cowboy boots yes sir

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