Which magazines for lock back Marvel??

I was running a new Marvel lock back conversion on a Sig 1911, I got 2 Jaggeman plastic mags with it, in late Summer when I bought it Marvel was having supply issues with the metal mags so I went with their plastic mags. They worked ok with the Sig frame but I had issues with lead shaving and jamming.  I sent it back to Marvel along with the magazines.

I finally got it back today and put the conversion on my new Caspian dedicated lower built by Jon and the Jaggeman magazine won't lock back when manipulated by hand, same thing happens using the Caspian frame off my 45 built by Jon. The 22 lower Jon built works great with my Nelson conversion using their plastic mags so I think I can rule that out.

So I'm going to contact Marvel again but am starting to lose patience. I'm hoping for some feedback on what has worked well for everyone else's Marvel lock back conversions.

The marvel lock backs I’ve seen used modified gag mags from marvel

Slide stop?
With the slide off insert the slide stop in the frame hold it in place and put some light downward pressure on it and insert an empty mag.  Does the slide stop move up?  If not look to see if it is catching the mag at all.  If not you they may have sent you the wrong slide stop.
- Dave

dronning wrote:Slide stop?
With the slide off insert the slide stop in the frame hold it in place and put some light downward pressure on it and insert an empty mag.  Does the slide stop move up?  If not look to see if it is catching the mag at all.  If not you they may have sent you the wrong slide stop.
- Dave

Well when I was testing stuff today the Nelson mags seemed to lock back pretty good in the Marvel conversion on the Caspian 22 dedicated lower. Also as I mentioned I ran the Marvel on the Sig for a couple months before sending in under warranty, it locks back fine on the Sig. I hope to actually get to the range soon to do some live fire testing.

One thing you have to keep in mind with marvel conversions is that the slide stop needs to be able to move freely with the action rod torqued down.
The slide stop lever and 'bolt' are are separate, and you need to leave a tiny space between the button head of the 'bolt' and the lever so that when you torque the action rod down tight, the slide stop can still move freely. This may solve your lockback issues.
If this does not make sense, let me know and I will send a picture.

I have a lockback model that works with GSG mags or earlier Metalform/Kart mags. I didn't know there was a newer magazine. 


Seems by your description the Sig frame might benefit from a different magazine catch that puts the mags a little higher in the frame. I had to add one to a Baer frame to get it reliable with a Kart conversion.

SmokinNJokin wrote:One thing you have to keep in mind with marvel conversions is that the slide stop needs to be able to move freely with the action rod torqued down.
The slide stop lever and 'bolt' are are separate, and you need to leave a tiny space between the button head of the 'bolt' and the lever so that when you torque the action rod down tight, the slide stop can still move freely. This may solve your lockback issues.
If this does not make sense, let me know and I will send a picture.

Could you please post that picture, I too am interested as my Marvel does not lock back anymore.

Well took the Marvel out today and it worked like a champ with the plastic Jaggeman magazines, only one magazine out of 30 failed to lock back. Perhaps I do need to keep an eye on how tight the stop pin is pushed in to avoid binding the slide stop.