The UltiMac, a modular Mac upper.

bigj480

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May I add a suggestion for the design?

It would be great if your upper shells had a quick and sturdy barrel change feature, at least better than the Dolos system.

I was going to start a thread about QD barrel systems. They make a lot more sense on our guns than an AR. From my quick search the most promising ones were the LEO Takedown and Dolos 2.0. Some considerations would be if you want to have the handguard and barrel married or if you want to be able to use one handguard for several barrels. How expensive or available is the barrel side of the mechanism because several will be needed for our purposes. Is it able to be easily removed while hot. I think a system not unlike the Fightlite MCR is probably preferable. Something that would work with a standard barrel, with no added piece, would be awesome.
 

theredneckengineer

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May I add a suggestion for the design?

It would be great if your upper shells had a quick and sturdy barrel change feature, at least better than the Dolos system.

I was going to start a thread about QD barrel systems. They make a lot more sense on our guns than an AR. From my quick search the most promising ones were the LEO Takedown and Dolos 2.0. Some considerations would be if you want to have the handguard and barrel married or if you want to be able to use one handguard for several barrels. How expensive or available is the barrel side of the mechanism because several will be needed for our purposes. Is it able to be easily removed while hot. I think a system not unlike the Fightlite MCR is probably preferable. Something that would work with a standard barrel, with no added piece, would be awesome.

I've given the quick change a lot of thought and put pen to paper several times in working on a design and I keep coming up with the same issues:
1. Handguard limitations
2. Barrel nut limitations
3. Cost, there's no way I could keep this thing in the $1k range if I had to make all the fiddly bits that come with a barrel change mechanism.

It may make more sense on a belt fed upper, especially if the handguard is integral to the upper, or at least somewhat "permanently" attached, like the Shrike/MCR.
 

bigj480

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I was not aware of the LEO system. Looks stronger than Dolos.

I actually thought the opposite might be true because the Dolos 2.0 ratchets down before locking. The LEO is almost like a pneumatic QD fitting. However, you do install shims on the barrel side to get tight fit initially. The only question is what happens as the ball-lock interface wears. Perhaps it would just mean adding a shim or maybe it would allow for twisting, IDK. I'm actually not very familiar with ARs, the LEO system would require a non-free float handguard, right? That doesn't bother me, just making sure I understand correctly since they say it replaces the delta ring. The only thing that sucks is worrying about gas tubes when the barrel is not installed on the gun.

Anyone know if it works on the m11/15? The dolos comes loose on mine and I am looking for a different system.

AFAIK it should, since the M11/15 accepts standard barrels and handguards. Well, If you have the ARM that is. Not sure about the IRM.
 

theredneckengineer

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Thanks to our network of farmers in this country, twice a year all the rest of us get to screw up our sleep schedules in their honor.
Since I was already up late watching LetterKenny due to my now-screwed-up-sleep-schedule, and I had too many bowls of the sugar cereals, I started looking at a quick-change barrel trunnion.

I think I have something that may work. I'll machine a couple and see if it works like I think it will, but I can't see why it would not.


The downside is that it adds about two inches to the front end of your UltiMac or AR upper receiver and thus pushes the handguard forward the same amount.
That means that s00per tactical, lightweight, uber-awesome 10" handguard you bought to work with your 11.5" barrel will now encapsulate the end of your fancy overpriced dragon-scale-nitrided 11.5" barrel and you will be a tactical-poopy-pants when you see that your rig is no longer high-speed, low-drag.


The gas system would remain unaffected. The gas block and tube would stay mounted on the barrel just like with other systems.

It may be a bit before I move further than just a drawing, and there will have to be trade-offs in order to have a true quick-change barrel, but.....it's something.
 

root

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You mean I was supposed to buy a 10.5 barrel???

I bought 16 and 20 inch barrels for the upper.

I do have some short barrels for my SBR's but really wasn't planning on using them

Wasn't planning on running a flamethrower on the upper!

.




I
 

theredneckengineer

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You mean I was supposed to buy a 10.5 barrel???

I bought 16 and 20 inch barrels for the upper.

I do have some short barrels for my SBR's but really wasn't planning on using them

Wasn't planning on running a flamethrower on the upper!

.




I

Barrel length is arbitrary.
I was mainly pointing out that my proposed idea for a trunnion may affect the handguard options.
 

strobro32

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Thanks to our network of farmers in this country, twice a year all the rest of us get to screw up our sleep schedules in their honor.
Since I was already up late watching LetterKenny due to my now-screwed-up-sleep-schedule, and I had too many bowls of the sugar cereals, I started looking at a quick-change barrel trunnion.

That means that s00per tactical, lightweight, uber-awesome 10" handguard you bought to work with your 11.5" barrel will now encapsulate the end of your fancy overpriced dragon-scale-nitrided 11.5" barrel and you will be a tactical-poopy-pants when you see that your rig is no longer high-speed, low-drag.

 

theredneckengineer

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Root... just gave me a good idea! Oh, the gun grabbers are gonna hate this.

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

In the event you bring the whole thing to Texas to hog hunt, I'll give you another upper gratis.
 

komodoj

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

In the event you bring the whole thing to Texas to hog hunt, I'll give you another upper gratis.



Strobro32 won dad of the year for his flame thrower. Anyone gonna do it, it will be Matt!!! He’s “Our” Mad scientist!!!
 

challenger70rt

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If I’m invited to hog hunt in Texas it’ll be coming... I suppose I’ll have to drive... I’m not really down with the proper protocol for baggage checking my flamethrowing-grenadelaunching-suppressed machine gun, but I’d imagine the airport tsa would shit a brick. It’s gonna be an interesting next couple of months. I just hope I don’t loose my eyebrows or beard... but the guy that does my nfa engravings sells flamethrowers now. I had been holding out to get one of the big expensive models, but I might have to grab one of them little guys in the interim.
 

Fishman

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If I’m invited to hog hunt in Texas it’ll be coming... I suppose I’ll have to drive... I’m not really down with the proper protocol for baggage checking my flamethrowing-grenadelaunching-suppressed machine gun, but I’d imagine the airport tsa would shit a brick.
not really. They dont care if its a single shot 22, or a transferable M2. You declare it as a firearm, the TSA looks at it, "yep, thats a gun", they put a special tag in the case and it goes onto the conveyor like any other bag. Sometimes they swab the case for some kind of chemical testing.

If I ever make it back to Texas for hog hunting, I'm bringing a 450 bushmaster mac10.
 

root

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Ya after seeing strobo's flamethower i'd have to say it's by far the best homemade thower i have ever seen.

Mounted under the redneck marvel would just be even more bad ass.

Like aliens queen chamber bad ass.

Rich
 

Gaujo

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not really. They dont care if its a single shot 22, or a transferable M2. You declare it as a firearm, the TSA looks at it, "yep, thats a gun", they put a special tag in the case and it goes onto the conveyor like any other bag. Sometimes they swab the case for some kind of chemical testing.

If I ever make it back to Texas for hog hunting, I'm bringing a 450 bushmaster mac10.

Nah man, I flew with a lage upper one time and the TSA agents were surveiling me around the freaking airport.
 

ecestu

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Thanks to our network of farmers in this country, twice a year all the rest of us get to screw up our sleep schedules in their honor.
Since I was already up late watching LetterKenny due to my now-screwed-up-sleep-schedule, and I had too many bowls of the sugar cereals, I started looking at a quick-change barrel trunnion.

I think I have something that may work. I'll machine a couple and see if it works like I think it will, but I can't see why it would not.


The downside is that it adds about two inches to the front end of your UltiMac or AR upper receiver and thus pushes the handguard forward the same amount.
That means that s00per tactical, lightweight, uber-awesome 10" handguard you bought to work with your 11.5" barrel will now encapsulate the end of your fancy overpriced dragon-scale-nitrided 11.5" barrel and you will be a tactical-poopy-pants when you see that your rig is no longer high-speed, low-drag.


The gas system would remain unaffected. The gas block and tube would stay mounted on the barrel just like with other systems.

It may be a bit before I move further than just a drawing, and there will have to be trade-offs in order to have a true quick-change barrel, but.....it's something.

Before I pass judgement, I need to know which sugary cereal put you in that blissfully creative state of engineering euphoria...
 

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