The UltiMac, a modular Mac upper.

[strobro32]

I think if you make uppers for $1K there will be no problem selling them. Additional features extra.

As far as quick change barrel designs, think MG42. oke

 

[Mackjack]

Mg42 barrel changes would be so cool

 

[Fishman]

I'm anxious to find out how much demand there really is for this upper.
Waiting lists are one thing, but people actually spending money is another.

 

[theredneckengineer]

I think if you make uppers for $1K there will be no problem selling them. Additional features extra.

As far as quick change barrel designs, think MG42. oke

Mg42 barrel changes would be so cool

While it is absolutely possible, it would require time, money, and lots of sugar cereals.

 

[IndustrialRescue]

How the hell do you ensure headspace with a barrel change like that?

 

[theredneckengineer]

How the hell do you ensure headspace with a barrel change like that?

If the barrel extension flange is pushed against the receiver barrel thread bung, no matter if it's a standard barrel nut or a quick change unit, then headspace is unaffected.
Headspace is set by chamber depth in relation to that same barrel extension, so there's no adjustment regardless of how it's secured to the upper.

 

[nimblebee]

Dinosaur gun flamethrower versus hog hunt

If you are going to mount a flame thrower under your UltiMac upper, I will pay to see that.

Reminds me of the dinosaur gun thread... "What hand-carried weapon would be sufficient for T-Rex"... My response "M1 Abrams or A-10 Warthog" was dismissed out of hand... I'm not sufficiently strong enough to carry either of those about!...

They came up with all kinds of ideas and suggestions... Including a flamethrower underneath the barrel lol... The most masterful design? ... It's likely I would be dismissed yet again, because I don't think I can lift the thing! lol...

What was the most long-winded rendition, let me think: ... Seems I recall...someone suggested a magazine-fed 12 gauge, accessorized with a pepper spray, blinding laser (in the dinosaur days I'm guessing there was no rules of War), flamethrower, flip out bayonet that injected CO2 into the Beast, multiple grenade launcher... Have I missed any points? ... It would be rather hilarious to see a picture of a caveman toting along one of these monstrosities, and T-Rex in the background slinking away with his tail between his legs!

I could no more pick up and carry something as extravagantly accessorized as this... You would have to create anti-gravity first, which is about as likely as anyone building such a contraption! lol



verkill

 

[nimblebee]

Mackjack: "Mg42 barrel changes would be so cool"

Forgotten Weapons Ian McCollum did an episode on the ZK 383 which had a nifty quick-change barrel, despite being a 9 mm handgun caliber carbine:

https://youtu.be/MlFdhAK5c7Q?t=133

 

[Mackjack]

Although quick change like a mg42 would be sick as fuck. I'd imagine that's something that could be added to the upper at a later date. No sense in delaying production for novelty

 

[skoda]

The Finnish KP31 Soumi SMG also has a quick change barrel system.

 

[theredneckengineer]

I have a ZK383 and several Suomi Kp31/M31s. Both have very simple barrel change/barrel jacket systems but it isn't quite as simple to apply something like that to the AR.

I actually have an idea that's close to the M60 or the Shrike using the same trunnion I designed before, but with latches on both sides instead of cam pins.

I agree that it will have to wait until I get approval and get everything off the ground.
Still, it doesn't hurt to dream, and all these ideas are helpful (or good for a laugh, in some cases)

 

[Vegas SMG]

Steyr AUG barrels are super easy to swap.

 

[theredneckengineer]

I managed to get out of the shop for a little bit today and test out the AK setup on one of my uppers.

 

[Swampfoxoutdoors]

]I managed to get out of the shop for a little bit today and test out the AK setup on one of my uppers.

https://www.youtube.com/watch?v=A6py4jvRbJw&feature=youtu.be

View attachment 35128

 

[theredneckengineer]

How did it run?

Any issues?

It went great until I had a round of m67 yugo blow apart on me and ruin both the upper and the bcg.
I've had several case separation issues with that ammo and I thought I'd pulled it all out of my mags and drums.
Otherwise, it wasn't a bad day.

 

[strobro32]

Ouch. Glad you're not hurt.

 

[theredneckengineer]

Ouch. Glad you're not hurt.

Yeah, me too.
My safety glasses took a good hit but I walked away unscathed.

 

[rhouston8]

It went great until I had a round of m67 yugo blow apart on me and ruin both the upper and the bcg.
I've had several case separation issues with that ammo and I thought I'd pulled it all out of my mags and drums.
Otherwise, it wasn't a bad day.

crap man. well you have your destructive testing sample .

 

[bigj480]

I know I've read about concerns regarding AR bolts shooting 7.62x39. have there been further developments regarding such bolts? IIRC, it left only a little material around the case head.

 

[theredneckengineer]

I know I've read about concerns regarding AR bolts shooting 7.62x39. have there been further developments regarding such bolts? IIRC, it left only a little material around the case head.

I have heard rumors of premature bolt failure in the 7.62x39 caliber, but I've shot my 7" and 11" 7.62x39 M16 uppers numerous times without issue.
There's easily 10k rounds on this bolt alone.
https://www.youtube.com/watch?v=DIo00oC0FuE

I'm guessing it was more of an issue when the original conversions came out. Shops were opening up 5.56 bolt faces and when machining the bolt, managed to leave stress risers in the bolt lug web. That will cause failures regardless of caliber.