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Posted: 12/29/2008 7:59:47 AM EDT
Built by MAS Gunworks ($600 delivered setup for FA with anti-bounce weight and trip, 5.5" barrel, YHM Spectre handguard). Currently sitting on one of my RR lowers but will probably live on one of the SBR lowers most of the time. Can is a Tactical Innovations Quest, scope is the inexpensive Vortex 1.5-4.
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I'm flagging this thread hoping for a range report. I've been considering one of these uppers from MAS and have a few questions if you write one: Does it use a Ciener/Model 1/CMMG/Spikes type conversion bolt assembly? Does it use a chamber insert or a modified chamber collar? How's it run in FA, and what ammo are you using? Does the MAS kit use both anti-bounce weight and ball detent?
Lots of questions - inquiring minds.... Thanks. texgriz |
So far I've only shot it at 25 yards to sight it in. Acccuracy is good, but I haven't really tried to wring it out. I was planning on working with it more to day, but it's currently 2 degrees outside with a wind chill around -10, so I probably won't go out to my backyard range anytome soon 
It uses a modified Ceiner without a chamber insert. The end of the conversion unit is milled to fit a matching milling in the barrel, so that it fits inside the barrel, with the 22 bolt acting on the milled portion of the conversion. My Rick Kuhn dedicated 22 upper uses a modified Ceiner ket where the bolt works against the end of the custom barrel; basically the end of the Ceiner kit is removed. Bad descriptions, I know. If I get a chance I'll take some pictures. The kit uses the anti-bounce weight, but no ball detent. So far it has run with every type of ammo I have tried, but works best with CCI Mini Mags; lower powered 22 ammo has had failure to extract where the fired round clears the chamber but gets stuck in the upper receiver; not clearing the ejection port. This happens in both semi and full. The mini mags run well in FA. |
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Sounds a lot like my experience with my current dedicated .22 upper, which I keep on a Sendra M16 RR lower that I've dedicated to .22 use, with the medium power Lakeside hammer and disconnector springs. The upper has a 5.5" Kuehl barrel and the conversion bolt assembly is a Ciener with Rick's modified breech adapter and a Lakeside recoil spring. It's suppressed with a huge 1.5" diameter custom 2 point mount reflex suppressor that extends back almost to the barrel nut with its expansion chamber, and forward of the muzzle about 6" with a blast chamber and 4 K baffles. This suppressor mounts inside a 9" rail and looks exactly like a 9mm SD until you notice the Black Dog mag. The outfit is surprisingly accurate with CCI sub-sonic and standard velocity ammo, with fairly consistent 3/4" 5 shot groups at 25 yards, which is as good as I can do with an Aimpoint 2 MOA red dot sight. It might do better with a scope with crosshairs.
I've had the same experience with occasional FTE with subsonic and standard velocity loads, which I prefer to use suppressed. It is definitely more reliable with high velocity mini mags, but the sonic crack sort of defeats the purpose of the suppressor. I was curious to hear if MAS had come up with a better mousetrap, but it sounds about like the same basic Atchisson design that Ciener and the other conversion manufacturers base their conversion units on. I was particularly curious to hear whether MAS is using a ball detent and anti-bounce weight together, and if that is a more effective system than the anti-bounce weight weight alone for FA fire with standard vel. ammo. I just got some of Black Dog's new extractors in, and I'm going to try one of them with a new spring to see if that helps with extraction. I believe the extractor groove on a lot of these units needs to be filed down just a hair to allow the extractor hook to get a better bite over the rim of the cartridge. The one I have now often won't manually extract a cartridge from the chamber, so I think a lot of the extraction in these kits is actually the fired case just being blown out of the chamber and hitting the ejector, rather than the extractor pulling it out. I'm also going to shorten the firing pin spring by about 50% to see if that will provide a better firing pin strike for more consistent ignition. I'll be interested to read more of your experiences with your unit as it eventually thaws out where you are and you have a chance to do more with it. Anybody that's running a FA with both the ball detent modification and an anti-bounce weight, or just the ball detent mod, I'd like to hear how that is working, especially with lower powered standard vel or sub-sonic ammo. texgriz |
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