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Discussion Starter #2
anyone? maybe I can get an answer if MR223 BCG is identical in shape to a standard AR BCG or not?
 

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anyone? maybe I can get an answer if MR223 BCG is identical in shape to a standard AR BCG or not?
Yes, BCG is virtualy identical. More importantly, the internal dimensions of the MR556 upper are the same as an AR15.

You *should* fit and work fine. I'd make sure to fire several 5.56mm rounds through the rifle at the end of every .22 conversion use to clear the gas port of lead buildup.

I've personally witnessed ARs run conversion kits to the point that the gas block becamed plugged and the rifle would not cycle once the regular BCG was returned to the rifle. Of course it took thousands of .22 rounds to do this, but it's best to make sure the gun functions and cycles properly at least every couple hundred rounds of .22.
 

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Discussion Starter #4
Yes, BCG is virtualy identical. More importantly, the internal dimensions of the MR556 upper are the same as an AR15.

You *should* fit and work fine. I'd make sure to fire several 5.56mm rounds through the rifle at the end of every .22 conversion use to clear the gas port of lead buildup.

I've personally witnessed ARs run conversion kits to the point that the gas block becamed plugged and the rifle would not cycle once the regular BCG was returned to the rifle. Of course it took thousands of .22 rounds to do this, but it's best to make sure the gun functions and cycles properly at least every couple hundred rounds of .22.
Thanks for the reply, I was talking to smith over the phone and he went to check if possible to fit that kit in MR223 and told me that it is not gonna work, it i snot going to sit in the chamber.
 

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Thanks for the reply, I was talking to smith over the phone and he went to check if possible to fit that kit in MR223 and told me that it is not gonna work, it i snot going to sit in the chamber.
I'm inclined to agree with this. I'm sure there is some variation between the dimensions of the BCG's to not allow them to be interchangeable. Just out of morbid curiosity, i'll probably try tonight and let you know.
 

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Discussion Starter #6
I'm inclined to agree with this. I'm sure there is some variation between the dimensions of the BCG's to not allow them to be interchangeable. Just out of morbid curiosity, i'll probably try tonight and let you know.
Hi, do you have that kit and your rifle is mr223?
 

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Not the kit, but surely if a standard AR15 BCG won't fit, i'm guessing it will be a no-go for the kit as well. One thing I wonder about is the cutout in the front portion of the carrier.
 

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Discussion Starter #8
that what I got from CMMG as response -Looks like it will. Looks like a standard AR platform. " :)
 

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Not the kit, but surely if a standard AR15 BCG won't fit, i'm guessing it will be a no-go for the kit as well. One thing I wonder about is the cutout in the front portion of the carrier.
Crap, I forgot about that.

I forgot about it because when I took my MR appart for barrel profiling, I removed the tab. With that tab there, it's highly unlikely that the .22 conversion will fit.
 

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Man, that's just plain aggravating! I'm pretty miffed that I spent >$2600 for an AR15 I won't be able to use with a .22lr conversion kit. Why does everything have to be so darned complicated for civilians?
 

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Man, that's just plain aggravating! I'm pretty miffed that I spent >$2600 for an AR15 I won't be able to use with a .22lr conversion kit. Why does everything have to be so darned complicated for civilians?
One could always buy/build a reasonably priced dedicated .22lr upper and save yourself the aggravation of dirtying up that fancy, unlined German barrel with rimfire. I would at least go that route before I bought one of the .22lr repros
 

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One could always buy/build a reasonably priced dedicated .22lr upper and save yourself the aggravation of dirtying up that fancy, unlined German barrel with rimfire. I would at least go that route before I bought one of the .22lr repros
a few hundred bucks more and you could just get a dedicated .22LR Umarex HK416 D
 

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Sorry for the resurection, but has anyone actually tried or verified if this will/won't work? I have a Spikes .22LR conversion I'd love to use if I aquire an MR556 upper.
 

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Yes, straight blowback, does not use any of the 5.56 mech. I know I can get a dedicated upper but I own the conversion and it's actually quite accurate in my Noveske upper. So, again, anyone tried it?
 

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So, again, anyone tried it?
I'm guessing no-one - since there's been no reply since 2012 :( I'll be trying this (HK MR223 and CMMG) sometime in the end of August or beginning of September. I'll be sure to include the results here. IF I manage to do it sooner, I'll be back here sooner :)
 
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