The_Vigilante Posted March 16, 2012 Share Posted March 16, 2012 Can I use the AR-15 magazines for the 300 blackout cartridges or do the mags have to be modified? If modified, what is the modification required? Thanks Link to comment Share on other sites More sharing options...
prreed10 Posted March 16, 2012 Share Posted March 16, 2012 So far, my unmodified Pmags have worked. 20's and 30's. I guess it depends on your OAL. The ridge of the mag is designed to run along the neck of the 5.56 but it ends up running along the bullet on the 300 BLK. Link to comment Share on other sites More sharing options...
LYNRDSKYNRD Posted March 17, 2012 Share Posted March 17, 2012 It runs fine in unmodified mags. Link to comment Share on other sites More sharing options...
Alaskapopo Posted March 17, 2012 Share Posted March 17, 2012 Can I use the AR-15 magazines for the 300 blackout cartridges or do the mags have to be modified? If modified, what is the modification required? Thanks The cool thing about the .300 black out is how easy it is to switch over to it from 5.56. No mags needed or a different bolt. You just need a barrel. Pat Link to comment Share on other sites More sharing options...
joelogic Posted March 19, 2012 Share Posted March 19, 2012 Once you start running the 300BLK round you will be able to tell by if the rounds feed or they jam. The new sierra 125gr bullets dont require the mag mod but when I load 150gr FMJ's to mag length they do bind. If you do modify them I am really liking my Lancer AWM mags with steel feed lips. Link to comment Share on other sites More sharing options...
cas Posted March 25, 2012 Share Posted March 25, 2012 The only mod you might need (may just help a little) is to round or bevel the inside edge of the front of the magazine. I had to do this back when I had my Whisper upper. It wasn't an issue while shooting, but sometimes chambering the first round the case mouth would hang up on the front of the mag just enough to slow things down and stop the bolt. Link to comment Share on other sites More sharing options...
oregonshooter Posted March 25, 2012 Share Posted March 25, 2012 My Pmags will not run 220 SMKs but they run fine in Brownells mags with Pmag no-tilts I tried dremeling out the pmags but still no joy. Link to comment Share on other sites More sharing options...
joelogic Posted March 26, 2012 Share Posted March 26, 2012 I had to use Wolff +10% springs to get 150gr bullets to feed reliability under heavy fire conditions. Link to comment Share on other sites More sharing options...
SC-Texas Posted March 27, 2012 Share Posted March 27, 2012 My pmags have run 220s just fine. I am switching to the lancer awm for 300 so I don't accidentally stuff a 300 blk in a 556 rifle one night. Link to comment Share on other sites More sharing options...
joelogic Posted March 27, 2012 Share Posted March 27, 2012 I switched to the Lancer AWM because I was breaking the feed lips on my Pmags. I believe from force of seating the mag. Link to comment Share on other sites More sharing options...
oregonshooter Posted March 27, 2012 Share Posted March 27, 2012 My pmags have run 220s just fine. I am switching to the lancer awm for 300 so I don't accidentally stuff a 300 blk in a 556 rifle one night. Interesting that they run in your Pmag but not mine. I gotta guess that you OAL is shorter than my 2.165" and the ogive is farther away from the Pmag guides that push my loads intk the center of the mag causing non advancement up the mag in my case. Link to comment Share on other sites More sharing options...
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