Compatibility between HK MR556 parts and the ATRS Modern Sporter receiver sets

CobraGT

CobraGT

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So I'm looking at sacrificing one of the ARs in my safe to provide parts for an ATRS lower, if and when I get one.

Does anyone know whether the lower receiver parts from an HK MR556 would fit an ATRS Modern Sporter receiver? Everything LOOKS compatible between the MR556 and my other Colt Canada receivers, but... are they? I've used Colt Canada parts in ATRS receivers in the past, so that is my other option, as I still have one unbutchered Colt Canada lower receiver.

Any actual info would be appreciated!
 
My opinion: just buy a lower parts kit and keep your HK original. If your pin punch slips while taking out the bolt release pin you’ll be cursing yourself and googling “how to fix gouge in anodized aluminum” (ask me how I know).

I don’t know if HK used proprietary parts but it would make sense that they are mil-spec and thus compatible. If you go that route, you’ll just need a rear takedown pin that works with the MS.
 
I will say you may want to swap guts with the Colt instead of HK - so to avoid wasting an afternoon of work and putting things back together to 2X the effort.

I have played with my share of HK MR and 416 type guns of a few generations. HK likes to pull little stunts in details that do not follow the program. Everything may work and then they went metric with one or two little things because they got them form germany.

I will say the chance is slimmer for US made MR556 because they were made by Daniel Defence back in the day. But if this is a EU MR223 I will not do it, if you have a colt Can. Take the path of less resistance.
 
I suppose? if U didn't have any "other" resources, it would make sense. My personal take, is that I usually use different parts from different manufacturers, so a Geissler trigger etc. I'd probably go the Colt or similar "mil-spec" route first & see how that goes.
 
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greentips said:
HK likes to pull little stunts in details that do not follow the program. Everything may work and then they went metric with one or two little things because they got them form germany.
Click to expand...

Mine's a US-made MR556, but the above is still exactly why I'm hesitating. If everything isn't exactly to the same spec as the Modern Sporter was designed to, well, obviously there would be problems.

Thanks to all of you for the thoughts; I'll probably just go with the Colt parts.
 
OP said he just wanted to swap lower receiver parts, why spend money on new stuff if there are unused parts laying around, other than saving time on disassembling.
 
lerch641 said:
Because of the upper and gas system, the only swappable parts are in the lower. But at that point, why bother?
Click to expand...

I figured there's no phucking way I'll ever turn over anything but stripped receivers to the Ottawa overlords, so why not use the parts in something else? But as long as there's a possibility of a future Conservative government, I decided to keep the HK intact.
 
I had an AR in my safe and I ended up taking it all apart and putting them onto my MS. It was then, when I had my MS fully built that whenever I'd go into my safe and see my AR receiver set staring at me, I had second thoughts about what I did. I ended up saying, fck it and bought all new parts for my MS and put all the other parts back onto the AR. hahaha!

It sounded good at the time but once everything is said and on the rifle, you might have second thoughts. Just my opinion.
 
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