How important is the recommended "extra meat" on the DPMS Lo-pro for an AR-47 build. I would prefer to use a Model 1 Sales(forward assist and dust cover) complete A3 upper and barrel, but don't want it to be weak after receiver mods. Is it really that critical. Semi auto 16" only. I'm not running FA or short barrel.

I should be able to tell you in a week or so as I chose to go with a CMT upper AND I will be running it in F/A.  The area that he cuts receives very little if any stress so it shouldn't be problem.

I use a DPMS Hi-Rider and Lo-Pro for my AR-47 and modular MGI lower.

Michael Otto (designer/inventor) of the AR-47 recommended the DPMS thick uppers to me and since I happened to already have those uppers I went with that.

If you look at the picture below you can see how a thin a "normal" upper is after modification:


I am running my setups in FA with a RDIAS.

I agree that I think those areas take little stress.
However, I am more concerned about the abuse my uppers take from getting banged around as I am rough on my stuff.
With that thin side wall, if it were to drop on it's side and something hit it in the clearanced area, I think it may break through.
I like the peace of mind of a thicker walled upper for the AR47/MGI setup.
If you are very careful with your stuff, I wouldn't worry about it and go with a regular upper.

AR47 lower


MGI Modular lower

SunDevil Billet upper receiver
Thick Slabside with ejection port cover and no forward assist/deflector



A little filing on the rear lug and it fits perfect!

I don't think it matters. I have a A3 with a DIAS and run it F/A. No problems yet

amphibian,
How'd you get that drum in the MGI? I didn't think that worked

Handbook,
Link to sundevil? Is the top rail the same height as a standard flat top, or slightly higher like a DPMS Lo-pro.? I'm looking to have the receiver rail be the same height as my FF HG top rail. "A little filing on the rear lug and it fits perfect!" ??? Can you explain that a little more.

http://www.sundevilmfg.com/
bought mine from http://www.rainierarms.com

The flat-top is same height as a standard forged receiver. The lugs on the SunDevil are slightly wider than mil-spec(even more so than RockRiverArms). It takes a little filing/sanding(easy 10minutes) to fit properly. The SunDevil also lacks feedramps, which are not necessary with AK mags, but good to have with Colt mags.

Quoted: amphibian, How'd you get that drum in the MGI? I didn't think that worked

You are correct, the first MGI AK magwells would not accept the drums.
The current version of the AK magwell will accept the Chinese drums.  Still won't work with the Romanian drums without mods though.