I have been having some issues with colt style magazines for my 9mm AR-15 SBR. I am hoping that someone here on INGO might be able to explain the why’s and wherefores’ of my issues.
I have experimented with three different manufacturers: Brownell’s, ProMag and ASC. My experiences have been as follows.
ASC is a metal mag with an orange plastic follower. It tends to be difficult to seat unless the bolt is locked back. It also tends to fail to feed the last couple of rounds. It will not hold the bolt back when the last round is fired. This holds true with both their 32 round and 10 round magazines (although the 10 round magazine is less likely to not feed all of the rounds in the magazine). The magazines are a relatively tight fit, not as sticky as the ProMag, but more so than the Brownell’s.
ProMag is also a metal mag with a black plastic follower. When empty, the follower sits much higher than either the ASC or Brownell’s magazines. Thus, when the last round is fired and ejected, the bolt does not lock open, but slams forward, striking the follower and begins to gouge large chunks out of it. This happens on both the 32 round and 10 round versions of the magazine. The magazines are a tight fit and require some effort to insert and remove.
Brownell’s works flawlessly, but they only make a 32 round mag, and I would like to find a 10 round mag to use when I shoot from the prone position. Their magazine is an all metal construction (including the follower). It seats into the magwell easily and holds the bolt open after the last round is fired. Magazines are easily inserted and removed from the magwell.
My primary question has to do with the bolt holdback feature. I do not see any significant differences between the Brownell’s and ASC magazines, but then I am not sure exactly how the bolt hold back is triggered when the last round is fired, so I am not sure what I should be looking for.
The SBR uses a Bushmaster receiver with a Hahn Precision top loading 9mm magwell adapter. The Upper is all CMMG
Has anyone else used ASC and/or ProMag magazines and experienced similar problems? I am thinking of trying out the AR-Stoner and Metalform 10 round magazines and see if I have any luck with them.
This image (left to right) shows the Brownell's, ASC and ProMag 32 round magazine followers. As you can see, the ProMag sits noticeably higher and is already starting to show damage from the bolt.
This image shows two Promag 10 round magazines and the damage the bolt causes to the follower. The one on the right is severe.
I have experimented with three different manufacturers: Brownell’s, ProMag and ASC. My experiences have been as follows.
ASC is a metal mag with an orange plastic follower. It tends to be difficult to seat unless the bolt is locked back. It also tends to fail to feed the last couple of rounds. It will not hold the bolt back when the last round is fired. This holds true with both their 32 round and 10 round magazines (although the 10 round magazine is less likely to not feed all of the rounds in the magazine). The magazines are a relatively tight fit, not as sticky as the ProMag, but more so than the Brownell’s.
ProMag is also a metal mag with a black plastic follower. When empty, the follower sits much higher than either the ASC or Brownell’s magazines. Thus, when the last round is fired and ejected, the bolt does not lock open, but slams forward, striking the follower and begins to gouge large chunks out of it. This happens on both the 32 round and 10 round versions of the magazine. The magazines are a tight fit and require some effort to insert and remove.
Brownell’s works flawlessly, but they only make a 32 round mag, and I would like to find a 10 round mag to use when I shoot from the prone position. Their magazine is an all metal construction (including the follower). It seats into the magwell easily and holds the bolt open after the last round is fired. Magazines are easily inserted and removed from the magwell.
My primary question has to do with the bolt holdback feature. I do not see any significant differences between the Brownell’s and ASC magazines, but then I am not sure exactly how the bolt hold back is triggered when the last round is fired, so I am not sure what I should be looking for.
The SBR uses a Bushmaster receiver with a Hahn Precision top loading 9mm magwell adapter. The Upper is all CMMG
Has anyone else used ASC and/or ProMag magazines and experienced similar problems? I am thinking of trying out the AR-Stoner and Metalform 10 round magazines and see if I have any luck with them.
This image (left to right) shows the Brownell's, ASC and ProMag 32 round magazine followers. As you can see, the ProMag sits noticeably higher and is already starting to show damage from the bolt.
This image shows two Promag 10 round magazines and the damage the bolt causes to the follower. The one on the right is severe.
