6Willbird, new wildcat large frame AR project ctg

willbird · July 5, 2020

I did notice the AR308 search term and almost always use it for search.

willbird · July 15, 2020

Ok had a chance to sit down with a depth Micrometer and the barrel extension today and double check with the new BCG for this build. Wanted to see if the hard chrome made a dimensional difference. For the most part it did not. Had I used the original dimensions or were I to swap BCG the hard chrome one would .003 more headspace. revised my drawing.

willbird · July 24, 2020

Ok for some stuff done today :-). Left barrel at 26" for initial test work and 1.2 dia, it kind of re defines "bull barrel" hehe.

Headspace is a bit longer than I want, will take the ext off and shorten that up. I used sharp corners on my gauge to measure cases and make a headspace gauge, the reamer has a radius at the neck shoulder junction. Easy fix.

willbird · July 24, 2020

Here is how it goes up in the lathe. There are far more than 1 ways to do this, one can get stuck on dead center so to speak the first time trying to decide the "right" way. I found the way that is right for me so far :-).

Final indicating here is with a .0001" indicator, and I get it .0000 runout or as close as possible.

willbird · July 24, 2020

This is what goes on at the other end of the spindle. I indicate the OD to get close, it is faster to eyeball than trying to get it close with the indicator up in the bore.

Matt.Cross · July 24, 2020

3 minutes ago, willbird said:

This is what goes on at the other end of the spindle. I indicate the OD to get close, it is faster to eyeball than trying to get it close with the indicator up in the bore.

You do final run-out check on the bore though, right?

willbird · July 24, 2020

2 hours ago, Matt.Cross said:

You do final run-out check on the bore though, right?

Absolutely, yes. The OD typically is not exactly concentric to the bore unless you turn it concentric. Indicator up in the hole is the best way IMHO. I have reworked a few factory 700 remington barrels where nothing ran true to anything else, when you got the bore dialed in all the other features were wobbling all over the place :-).

Bill

Edited July 24, 2020 by willbird

Matt.Cross · July 24, 2020

10 minutes ago, willbird said:

Absolutely, yes. The OD typically is not exactly concentric to the bore unless you turn it concentric. Indicator up in the hole is the best way IMHO. I have reworked a few factory 700 remington barrels where nothing ran true to anything else, when you got the bore dialed in all the other features were wobbling all over the place :-).

Bill

Absolutely agree with you there, that's right on par with cutting a barrel down on length, threading the muzzle by the concentricity of the OD, and then adding a suppressor.

Bafflestrike anyone?

willbird · July 25, 2020

Ok adjusted the headspace issue. and where this was all leading, or the next step was...

Will 5 dummy rounds made from fire formed and resized cases feed from a Pmag working the bolt by hand ??

The answer is............yep like butter. These are 75 VMAX, fore formed with a maximum 243 load of superperformance.

Edited July 25, 2020 by willbird

willbird · July 25, 2020

Fire formed cases hold 57.0 grains of water maximum case capacity overflow which is what QuickLoad shows for 243AI.

98Z5V · July 26, 2020

Jesus, man, this thing is gonna be a SCREAMER!!! :lmao:

willbird · July 29, 2020

On 7/25/2020 at 9:27 PM, 98Z5V said:

Jesus, man, this thing is gonna be a SCREAMER!!!

105 AMAX will fit, they are a sort of stubby bullet for weight, and in a 26" barrel could hit 3126 fps, but my 1:10 rifling twist will probably not stabilize them. QL says 2847 in an 18". Apparently the 105 AMAX I have are collectors items :-). .500 BC, they were one of the first polymer tip 6mm heavies as I recall. They are not nearly as explosive as vmax.

98Z5V · July 30, 2020

13 hours ago, willbird said:

105 AMAX will fit, they are a sort of stubby bullet for weight, and in a 26" barrel could hit 3126 fps, but my 1:10 rifling twist will probably not stabilize them. QL says 2847 in an 18". Apparently the 105 AMAX I have are collectors items :-). .500 BC, they were one of the first polymer tip 6mm heavies as I recall. They are not nearly as explosive as vmax.

Yep, they're calling 1:8" twist these days, for the heavies. 103gr ELD-X (.512 G1), 105gr HPBT (.530 G1), and 108gr ELD-M (.536 G1) from Hornady are pretty badass. My 6 ARC is a 1:7" twist, so I'm gonna shoot the heaviest thing that I can find for that bastard. Right now it's the 108 ELD-Ms. 200 factory loaded rounds already waiting, and another 300 to load and "determine my handload..." After that, I'm switching to the 110gr A-Tips. They're rollin' a .604 G1, which is just crazy.

The .243 Win bolt gun I have is a 26" heavy barrel, but it's a 1:9 1/8" twist. I think I'll stick to the 95gr stuff for that, which are still good. I'll try some heavies in it, and see what it likes. If it doesn't like any 103, 105, or 108gr stuff - I'll just load that up and shoot it through the 6 ARC.

willbird · July 30, 2020

13 hours ago, 98Z5V said:

Yep, they're calling 1:8" twist these days, for the heavies. 103gr ELD-X (.512 G1), 105gr HPBT (.530 G1), and 108gr ELD-M (.536 G1) from Hornady are pretty badass. My 6 ARC is a 1:7" twist, so I'm gonna shoot the heaviest thing that I can find for that bastard. Right now it's the 108 ELD-Ms. 200 factory loaded rounds already waiting, and another 300 to load and "determine my handload..." After that, I'm switching to the 110gr A-Tips. They're rollin' a .604 G1, which is just crazy.

The .243 Win bolt gun I have is a 26" heavy barrel, but it's a 1:9 1/8" twist. I think I'll stick to the 95gr stuff for that, which are still good. I'll try some heavies in it, and see what it likes. If it doesn't like any 103, 105, or 108gr stuff - I'll just load that up and shoot it through the 6 ARC.

Lots of internet folks feel that people who say the 105 AMAX works for them in a 1:10 actually do not have a 1:10 :-). I can hook you with a few 105 AMAX, they are coated with something called "Danzac"...which is a kind of moly spin off product, Titanium Disulfide maybe :-). Does not look like Green Mountian makes anything tighter than a 1:9. Shame really, their product seems good and the price is good, and lots of stuff is "in stock:.

Bill

willbird · August 15, 2020

Ok needed to measure exactly where the gas port needs to be with a white oak rifle minus 1" gas tube.

made this jig here.....allows putting the BCG end of the gas tube right in the center of the cutout in the upper.

They sell this tubing at most hardware stores, it is a Hillman product, not too expensive.

Lathe turned this up so that it clamps up like a barrel extension.

The answer I got was 1.221" closer to the receiver than a rifle gas 18" faxon pencil barrel. That all makes sense because it is a White oak AR15 rifle length gas tube minus 1", which amounts to Armalite AR10 rifle length gas tube minus 1.25" :-).

Edited August 15, 2020 by willbird

Matt.Cross · August 15, 2020

That's creative thinking right there! I love it!

willbird · August 15, 2020

13 minutes ago, Matt.Cross said:

That's creative thinking right there! I love it!

When you need to do something there is always a way :-). That could all be made out of wood dowels actually and it would still do the job, maybe not the .001" but def good enough to work :-).