View Full Version : BCM Pistol Lower and Gen 3 Pmags
CajunCourier
04-22-19, 08:31
My next AR is going to be an 11.5", and I'm leaning towards BCM. I keep reading about how some BCM lowers won't accept Gen 3 Pmags, which happens to be the most numerous kind of my magazines. Is this a deal breaker for any of you? I suppose if I get one that doesn't accept Gen 3s I could just buy and use Gen 2s, but this is going to be my bump in the night gun and general do-it-all AR (classes, range, home defense, etc).
As of right now I was going to get a BCM pistol lower w/ brace while I wait for the SBR paperwork to come back.
My BCM lower takes gen 3 pmags just fine. Only one of my lowers is a BCM though, small sample size.
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Eurodriver
04-22-19, 08:54
My BCM power takes gen 3 pmags just fine.
I have three lowers that won't drop free G3s: BCM, KAC SR15, KAC USGI lower. Gen2s work fine and drop free, but not Gen3s. If I recall BCM stated that some Pmags are sized differently in one dimension that the milspecs don't control for. I forget which it was though.
My 2c:
No matter what lower you get - don't buy sight unseen. Even if it costs you a $20-50 extra just buy it locally - you'll be able to see and test it personally to make sure you're happy with it. That's probably the main issue with regulated items that you can't really easily exchange it.
There have been too many cases on this site where people were excited to buy something unique, or cheap, or not available locally and then discovered a blemish or some issue (actual or perceived) and were unhappy about it.
turnburglar
04-22-19, 12:44
Some people havent had an issue and some have. As reported even other high end manufactures seem to have issues.
I dont know why people are so hesitant to take a small ammount of sand paper to polymer if "drop free" is that important too you. Call it 'custom gunsmithing', 'tactical clearancing' or what ever you want. I have over 30 PMags from G2 -G3 and have never noticed an issue.
CajunCourier
04-22-19, 13:02
My 2c:
No matter what lower you get - don't buy sight unseen. Even if it costs you a $20-50 extra just buy it locally - you'll be able to see and test it personally to make sure you're happy with it. That's probably the main issue with regulated items that you can't really easily exchange it.
There have been too many cases on this site where people were excited to buy something unique, or cheap, or not available locally and then discovered a blemish or some issue (actual or perceived) and were unhappy about it.
If I could I’d buy locally, in person, in a heartbeat so I could inspect it before giving my money. Unfortunately, that’s not an option. Nowhere around here has what I’m looking for. In the past I’ve ordered a gun that was defective, and I was able to return it upon inspection at my FFL because I hadn’t done the paperwork yet.
WTF? I just bought a LMT lower and it won’t drop Gen2’s. I thought Gen 3s were closer to the dimensions of a GI mag on top of addressing the the feed angle need for the new army ammo.
I was looking at BCM fir another build but may have to cross that off the list. Both my Colts work fine with all mags so I’m not sure I believe this mil spec excuse.
I have had lowers that have had drop free issues, I dont own them anymore. I am of the opinion that any lower I own must work with all magazines that I own, meaning pmags, usgi, tango down, emags, Daniel Defence, and lancers. I would consider all those quality magazines. If a lower does not work with them I dont continue to own the lower.
The BCM issue I think you are referring to has to do with the overtravel tab of the Gen 3 PMAG not allowing the mag to fully seat into the lower. If I recall correctly it's a small % of lowers that have this issue. I still recommend BCM to friends and family but tell them to bring a Gen 3 PMAG to test for when they go to pick up their new AR or lower. To me this issue is far more egregious than the drop free issue but others disagree.
As mentioned previously try to buy local and if you can't, test before you do any paperwork and use a good FFL that will send it back if you reject it. Don't think that you can deal with it later with the company as with the BCM issue they may tell you it's the PMAG that out of spec.
CajunCourier
04-22-19, 15:32
WTF? I just bought a LMT lower and it won’t drop Gen2’s. I thought Gen 3s were closer to the dimensions of a GI mag on top of addressing the the feed angle need for the new army ammo.
I was looking at BCM fir another build but may have to cross that off the list. Both my Colts work fine with all mags so I’m not sure I believe this mil spec excuse.
That's the thing, it sounds like if it can happen with BCM, LMT, and KAC lowers, it can happen with anyone's. I've been reading on here about people with Colt LE6920s that won't take the Gen 3s either, and it doesn't get any more mil spec than that.
I have lowers from four different brands (BCM, PSA, Sionics, and Spikes) and all will take and drop gen M2 and M3 Pmags just fine. When I bought my BCM there was a lot of drama at the time about whether their lowers would readily take gen M3 mags. With the others I just got lucky I guess. When I bought that lower I was working at a shop that carried BCM so I made sure to get one that dropped them freely. I recall when this issue first came to light BCM took the stance that their lowers are designed specifically to take mil-spec mags and that anything else is basically a crap shoot. However, that was before the gen M3 Pmag became the de facto military magazine. I guess BCM hasn't changed their position.
The magic number appears to be .90 - anything that wide or wider I have found not to have any issues.
That's the thing, it sounds like if it can happen with BCM, LMT, and KAC lowers, it can happen with anyone's. I've been reading on here about people with Colt LE6920s that won't take the Gen 3s either, and it doesn't get any more mil spec than that.
First time I hear about 6920's having issues with PMAGS. Maybe was a bad run or something.
I have had lowers that have had drop free issues, I dont own them anymore. I am of the opinion that any lower I own must work with all magazines that I own, meaning pmags, usgi, tango down, emags, Daniel Defence, and lancers. I would consider all those quality magazines. If a lower does not work with them I dont continue to own the lower.
It's an interesting and very stringent criteria. I totally understand and agree with that approach not just in magazine well tolerances.
I've never experienced this issue, but I don't think that a drop free Magpul Gen 3 would be a hard requirement if lower is otherwise quality and in spec. Difficult to seat or noticeable binding to extract the mag - definitely an issue.
I think I'm just going to have to order it from Buds and have it shipped to my FFL. If I remember correctly, Buds will accept returns on new guns as long as it hasn't been transferred yet, so I'll just inspect it by bringing a few of my own Gen 3 Pmags and making sure it inserts and drops free before starting the paperwork.
Personally, there is a large difference between the magazine not leaping free with the press of a button, and the magazine being hard to wrangle out.
I have more BCM lowers and complete weapons that I can think of off the top of my head, and no magazine issues with any.
goaltendah1
04-23-19, 17:32
I own many BCM lowers/rifles and have zero issues with magazines.
My newest Colt 6920 that I bought last year (CR Serial number prefix) will NOT drop a Gen 3 mag free. I've bought BCM lowers for the last few years and have had zero problems.
Jeff
I got into the old threads about this just over a year ago, I believe. Brought a M3 magazine and tested the magazine drop at the FFL. No problems, everyone was happy. It was s fairly recent manufacture, as I emailed BCM out of curiosity. I’d guess you’ll be fine. Worst case, you’d pay to ship it back.
My next AR is going to be an 11.5", and I'm leaning towards BCM. I keep reading about how some BCM lowers won't accept Gen 3 Pmags, which happens to be the most numerous kind of my magazines. Is this a deal breaker for any of you?
Not a deal breaker for me. Can't expect a gun maker to chase every mag or mag revision under the sun to make sure it falls all slick like when you smash the button.
Not a deal breaker for me. Can't expect a gun maker to chase every mag or mag revision under the sun to make sure it falls all slick like when you smash the button.
Just to be clear the problem with BCM lowers was not their ability to have mags drop free it was that the over insertion tab on the Gen 3 PMAGs was not allowing the mag to seat all the way.
Not a deal breaker for me. Can't expect a gun maker to chase every mag or mag revision under the sun to make sure it falls all slick like when you smash the button.
Just to be clear the problem with BCM lowers was not their ability to have mags drop free it was that the over insertion tab on the Gen 3 PMAGs was not allowing the mag to seat all the way.
Exactly. Also, the Gen M3 PMAG is the only mag other than USGI that entire BN and larger units in the military are using so it’s as close to a gold standard as there may ever be.
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Just to be clear the problem with BCM lowers was not their ability to have mags drop free it was that the over insertion tab on the Gen 3 PMAGs was not allowing the mag to seat all the way.
Gotcha, my reading comprehension was a bit off.
Just thought I'd give an update. I ordered and received a BCM complete rifle lower the other day, and it does take all my Gen 3 Pmags without a hitch. They drop free just fine like any other AR, too. I chalk the compatibility concerns to things being overblown on the internet.
If you care to read 26 pages on the matter:
https://www.m4carbine.net/showthread.php?169913-Problem-with-a-new-BCM-lower
or 19 more pages:
https://www.m4carbine.net/showthread.php?205190-BCM-Lower-not-compatible-with-PMAG-Gen3
If you care to read 26 pages on the matter:
https://www.m4carbine.net/showthread.php?169913-Problem-with-a-new-BCM-lower
or 19 more pages:
https://www.m4carbine.net/showthread.php?205190-BCM-Lower-not-compatible-with-PMAG-Gen3
I've read those before, but reading them again did get me curious about how it would do with a closed bolt and fully loaded Gen 3 Pmag with seating and drop free. I took an upper off one of my other ARs and put it on the BCM lower, then loaded up a Gen 3 Pmag to 30 rounds. It seats and locks in easily and without issue, and drops free, so I guess I'm one of the lucky ones. I wouldn't have been too happy if it didn't. I get the impression that it's a very small number of lowers affected, but that doesn't make it suck any less for the few who do get them, especially for someone that may have to rely on another officer's mags at some point. I'm happy that this lower is GTG though.
I only have 1 BCM lower, but it has performed flawlessly with over 20 different PMAGs, including 10's, 20's, 30's, and a D60. Most of them are Gen M3 mags, but some are Gen M2. As a BCM fanboy I find BCM's official standpoint on the matter childish and disappointing considering MOST other brands have no problem with M3 PMAGs, but if you're one of the unlucky few I'd just modify the lower and be done with it.
You could've just read the 60+ thread that discusses this matter ad nauseam.
Beat Trash
05-07-19, 12:40
I was one of the people who started a thread on the issue I had with a BCM lower not working with a M3 PMAG. That was a few years ago.
Couple of months ago, I reached out to BCM about this issue, now that the M3 PMAG is an issued magazine within the Marine Corps, as well as several Law Enforcement agencies, to include mine.
To the OP, I’d go with the BCM lower.
I was told in the email I received that all current BCM lowers are now compatible with the M3 PMAG. From the few newer BCM lower receivers I’ve handled over the last year, I believe them.
I was one of the people who started a thread on the issue I had with a BCM lower not working with a M3 PMAG. That was a few years ago.
Couple of months ago, I reached out to BCM about this issue, now that the M3 PMAG is an issued magazine within the Marine Corps, as well as several Law Enforcement agencies, to include mine.
To the OP, I’d go with the BCM lower.
I was told in the email I received that all current BCM lowers are now compatible with the M3 PMAG. From the few newer BCM lower receivers I’ve handled over the last year, I believe them.
That's good to hear, I'd been hoping that they would just quietly address this since it didn't seem like they would do it openly.
I too have a BCM rifle I bought a few years ago. I takes USGI mags (mostly D&H Industries made), PMAG G2 and a few newly purchased (in the last few months) PMAG G3 mags equally well. Can't tell a difference. I've shot the rifle a fair amount, and have north of 3K rounds through it.
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