Ok i’m probably wasting my money, but i’ve got a Colt H buffer and carbine spring on the way from grant…
magpul hasn’t yet gotten back to me on mags…
I’ll run some M193 and some hotter TAC/hornady brass handloads next range visit (probably this weekend) and get back to yall. It’s a pretty easy to reproduce problem (was happening basically every time with those mags) so i should be able to get fairly scientific with it.
You should acquire more than 2 magazines.
This could easily be a magazine+rifle problem, and if you keep using the same propblem parts, well, you’re going to have problems.
Try out 5 or 6 different mags. If you are still having the same problem with them all, you know it’s a gun problem. If not, you can isolate the bad mags. Either way, you at least have some more mags.
if its really overgassed, you could look into a wolff xtrapower spring.
for the overgassing causing double feeds, IDK, but i could see it happening. My bro had a bad extractor that caused double feeds. Apparently the empty casing was bouncing around the inside and knocking the top round out of the mag while the bcg was fully rearward. The the empty would pop out. (not one fte but a ton of double feeds… every 3 or 4 rounds). The bcg would then move foreward and strip a 2nd round into the chamber and… double feed.
Thinking that a bcg is going to jar the gun enough to do the same is not far fetched, especially if it feels extremely overgassed.
Double Bullshit!
This thread just keeps getting better and better. ALL double feeds are the result of bad magazine. You are confusing causation and correlation.
For an empty case to bounce around in the action, the battle buddies (ejector & extractor) are not functioning properly. Further, there is no possibility that a spent cartridge has enough chutzpah to cause a serviceable magazine to release a cartridge and still get its little brass ass out of the action before the weapon starts counter recoil.
If your weapon is over gassed to the point that there is enough energy to cause a cartridge to be ejected from a serviceable magazine, when the bolt comes to its usual and sudden stop at the back of the receiver extension, the barrel is the problem not the magazine. At this point, changing parts (buffers, action springs) in your weapon to get a serviceable magazine to work is just an asinine endeavor.
Reinforcing what others have already said, why have you not tried different mags in YOUR gun first? 
This thread is making my head hurt. When troubleshooting it is always prudent to narrow down the issue. In this case you are using shit ammo and possible not so good magazines.
Go to a local store and pick up some USGI mags or order a few online. Then get some decent ammo and see what happens. If it works then try the Wolff again and see what happens. If it works then you know it was the 20rd. Magpuls.
Right now you are chasing magical unicorns in fields of poppies.
May I ask why not use a spikes powdered buffer?
it wasnt bad mags.
Well it happened a couple years ago, it MAY have been one round getting shoved up between the bolt and the CH recess. But I im pretty sure it was double feeds. My brother doesnt remember. There were lug/receiver ext marks pounded into the case every time it malf. The empty case was enough to at least toss a fresh cartridge around in the chamber, and still eject (the gun never had a FTE).
Bottom line is, the OP should check everything out. Checking extractor is free and he can at least look at it. If its not that then go buy some pmags or something, or try someone elses mags.
Its not bullshit, its speculation. Is it likely? No, but it doesnt cost a dime and there is no reason not to look into it.
OP, load some dummy (or if your careful, live) rounds and slowly cycle the action while pushing on the bottom of the mag, if it starts to strip 2, you can toss the mags. I was gonna say this earlier, but was thinking of pistol mags for some reason (2 days on 4hr sleep = wrong thinking).
Why ?
While, personally, I have no problem with shooting it… it seems a lot of people don’t like it because it is often considered under powered. Some also complain it is dirty. I have a feeling he is referring to the power more so though. Just a guess, I can’t speak for him.
edit: Nevermind, you’re a Senior Member - I’m probably preaching to the choir lol. Sorry!
It’s fairly weak, nasty and dirty with so-so quality control. Now, if the weapon was running 100% and he wanted to try it out- great. But, to use it while troubleshooting I wouldn’t do it. YMMV
Not picking a fight but I see a contradiction in those paragraphs, highlights are mine. I agree that swapping parts to make up for what could be too large of a gas port is half stepping.
Last set up I saw do this was a gun show special sent in from a guy in VA. I don’t know the progression of the “repairs” but it was a collapsible stock with 1/3 of a rifle spring in it using the front half of a rifle buffer and a gas port (16" LW contour) that took a #30 bit with some wiggle.
Oddly enough it came in with the “occasional malf” problem and only really started screwing up when I installed the correct buffer and spring. That lead to discovering the gas port issue. Initially tested with my known good mags (issue USGI) and ammo (issue M193) then with his supplied beater USGI and Barnaul.
ok… so here’s my plan:
load ammo to same spec i had trouble with ~60rounds
(24 grains TAC .030 over min OAL)
load some 25 grain and 26 grain (30 each)
try original ammo with both the colt H buffer and my original palmetto buffer.
try with the “problem mags” as well as some other P-mags and USGI mags.
i have 6 p-mags with the same date code. (6/08) as the 2 known problem ones.
I’ll report back.
Post pics. 
Ok guys, seems to be the mag.
I am keeping the heavy buffer though.
I loaded one of the known problem mags with 4 rounds, and got it to run fine 3 times (12 rounds) then on the 4th attempt it did a double feed. The double feed was not nearly as severe as last time, the second round just got its nose in far enough to keep the bolt from seating fully.
So… I’m going to give magpul a call tommorrow and see if they’ll replace the 6 mags with that date code. (2 of which i’ve had double feed issues with) Also none of those mags drop free from my lower… Perhaps a bad batch?
A far as H-buffer testing- the fact that it seemed to reduce the severity of the double feed is a plus. i also tried it with some minimal TAC loads- 23 grains. No trouble locking the bolt back. did that 10 times in a row… I dont’ think I’m having any under function issues…
so overall i think I’m good on this issue. my other p-mags functioned flawlessly, and the gun was of course great fun to shoot.
I wouldn’t be surprised that is the lower. I think I have read other issues with LRB Arms lowers. If they made it on the tighter end of the spectrum combined with a thicker mag I can see it.
yeah i have no doubt it’s on the tight end of the spectrum as far as lowers go. I might pick up a spikes lower or something at some point, though i have a few p-mags that do drop free from this one.
Because high-speed video testing shows the segmented weight buffer works much better.