Hey
Having some issues with my colt pattern 9mm AR. I can load EMPTY mags easily with bolt closed or locked back. I can load full mags (1-30 rounds) with bolt locked back. I CAN'T load full mags (1-30 rounds) with bolt closed. I've cut my hand trying to slam it in during local matches, still won't lock in.

The shorter version....

Bolt closed....
Empty mags, yes
Full mag (1-30 rounds), no

Bolt locked back......
Empty, yes
Full, yes

PSA upper, with 9mm hybrid bcg
Hahn bottom load mag block
Metalform mags

Not sure if it's the bcg, mags or mag block???
Rounds do hit the bottom of the bcg when trying to lock mags in. Any info on what it could be and how to fix the problem would be awesom!
Thanks

Mine was the mag block moving, which was throwing off the alignment of the mag catch, so I used black RTV silicone to keep the mag block in place.

a friend has the same problem using a dedicated Colt mag lower with no mag block.... he has to use a MagLuLu to load the mags, very difficult to hand load #32 where my Glock mag easily hand loads... appears to be the force needed to push the top rounds down to reach the catch

Short answer - more upper body workouts and some gloves

Long answer - I have had the same issues with new mags - I disassemble all of my new Metalform mags to clean them, then run a paint stirrer stick up/down about 50 times in each, then load them with a maglula and let them sit for a week or so.  Once broken in, I haven't had any issues.  I have one full round of movement in a full mag when loaded to 32 rounds.  I could squeeze in a 33rd, but then the stack of rounds has zero movement.  This has worked for me and I always reload on the move with bolt closed - haven't had any mags not lock in.

The only thing that confuses me is where you said you could insert an empty mag on a closed bolt, but if you even have 1 round in the mag, you couldn't?

I have a dedicated Colt lower and have found that tightening the mag catch a turn or two helped. Might not always work, but it places more catch into the mag well.

Denatured alcohol dissolves the typical preservatives that come on firearms parts.

I did take them apart and wiped the insides of the mags, didn't use any cleaners though. I'll do it again with a cleaner. I'll load them up as well and let them sit.

And yes, even with just 1 round in the mag, I can't get the mag to lock in when the bolt is closed.

This is a common complaint. My RRA colt pattern (Hahn block w/Metalform mags) does the same. Even downloading a few rounds is still difficult to seat, and for me it's hard to tell if I've got the mag fully seated unless I slap it hard.

As mentioned above, these mags are hard to load by hand, so it takes a lot of force to get the rounds to drop down low enough for the mag to seat. This is the only reason I added a long finger bolt catch to mine for LRHO, so I can load mags on an open bolt.

At least when 5.56 PMAGS need a slap they stay in place when initially seated. None of my Metalforms will unless the mag catch engages.

I've had my AR9s and metalform mags for many years and shot quite a few matches with them and other stuff that requires mag changes on closed bolt.  They are a little more difficult than other guns I have, but not so much that I've ever struggled with them, had mags fall out, or cut my hand.  If you can't even get a mag with a single round in it to lock into the gun on a closed bolt without too much effort, then it sounds like there is something else going on.

That's what I'm trying to figure out , I cleaned the crap out of the mags and was able to get 32 rounds in every mag. A little tough but not crazy difficult. I'll let them sit for awhile. See if it gets any better. Thanks for the different ideas and info.

It's an issue with all AR9.

Even the factory colt 9mm won't load on a closed bolt. It has to do with the design.  

If you are doing USPSA classifiers and have to have a reload what I do is load up exactly your round count you need and then don't miss lol.

Also I suggest one of the bolt catches that have the extra lever so it's easier to lock the bolt back if you need to because of malfunction ect.

The standard M16 will do this to a lesser degree. If it's that hard to load the last round, then that is the exact amount plus more to force the loaded mag against a closed bolt. If the mag catch doesn't - out it pops.

It's why the M16 has a bolt hold open - to avoid jamming the loaded mag into it with the higher risk of the mag catch not working, and to prevent the extra motion of pulling the bolt back to chamber the first round, which takes time. Unlike more primitive firearms like, say, the AK.

Actually a normal hangup for a lot of mag fed firearms. Note the Garand enforces it pretty well, too, and those newer designs to circumvent CA law now load a "stripper" clip thru the ejection port. Bolt much be to the rear, of course.

It sounds like a finesse point but since it is, use it to full advantage as that is what competition forces you to do - adopt every small finesse necessary to reduce stage times and manipulation of the firearm. Like shotgunners introducing the fire on release binary trigger years ago. It speeds up response on doubles.

Embrace the open bolt. It's less sucky.

That's an interesting take that I can't say I recall ever hearing before.  Do you know if Colt purposely designed it that way or was it discovered as a flaw after some time?

I can insert a full mag in all of my AR9s with a closed bolt.  It may require a little more effort than other guns, but the process is still the same and I don't really notice the difference in practice.  I don't do enough training myself, but the train like you fight concept is always appropriate.  I like to participate in shooting "games", but I'm not going to do silly stuff like loading my mags with a specific # of rounds so I can try to plan for a reload on an open bolt.

I guess that's just what I was told I don't know if it's an actual flaw per say just that it has been noticed by shooters. I thought it was just an issue with mine as I run a mag block but after talking with people with dedicated lowers they had the same issue.

Also it's a game.  Your whole train to fight argument is flawed as why would you use a 9mm AR in that situation.

Sure you can load on a closed bolt but it's a pain in the ass and I have found it quicker and easier to "game the game".

As I said, it is a bit more difficult than some guns, but I'm not an athlete or strong man and I just don't get the PITA stuff.  I can do about 2 pushups, maybe 1 pull up if I'm lucky, and am stoked if I can bench mid to upper double digits.  If you really find it to be that much of a PITA, then I don't know what to say.

I set up my primary AR9s a long time ago as training companions to my 5.56 guns so I could shoot more often for a lot less $, and since most of the PCC/IPSC style matches I shoot typically max out at 25-50 yards, it seemed silly to burn .223/5.56.  I have been to some indoor matches that only allowed handgun calibers, so it was the AR9 or nothing.

When I shoot matches, I don't purposely try to game the game.  I shoot and move as needed.  Unless there are forced mag changes, I typically try to time mag changes while on the move (closed bolt), instead of shooting to slidelock and then reloading wherever I may be standing.

Do the bolts have the glock cut on the bottom?  Perhaps the cut is too much on some bolts and it is causing the top round to be pushed outward in the mag, instead of downward.  Maybe those with severe closed bolt insertion issues can try inserting mags where the top round is on each side and see if there is a difference when inserting on closed bolt.

It can be done but when you are gaming might as well do what will make you the fastest.  

I recommend a different bolt catch so it's easier to manipulate.

Also I wonder if different manufacturers blocks make it any easier? I run the promag and didn't have issues until an OOB cracked it. I found out today that their new block made in house will be available soon. So currently just waiting to send it in and get the new version.