Marvel conversion help

[Chuck]

Hi,

My Marvel conversion on my Greg Derr tuned Colt 70 series frame just doesn't work. In 45 mode it functions flawlessly. When I put on the Marvel I usually get a jam where the extracted case doesn't get out of the way. See the pic - this happens 2-3 times per mag.

I've tried multiple mags. Multiple flavors of 22. 4-5 didn't weight recoil springs.

Looking for ideas from someone who's seen this before or can recommend a 'smith who's gotten Marvel's to run right who can take a look.

thanks,
Chuck

 

[Gammon]

I have had a Marvel Long Slide Conversion on a Colt frame for many years, and have a few ideas but must know which conversion you have; full slide or skeletonized slide with sight or rib mounted to the barrel.

 

[Chuck]

Thanks for what ever help you can give. I have the Steel Unit 1 with last shot hold open. It has the full length red dot mounting rib; seen in the picture. Was thinking of upgrading to the rib with sights for iron sight practice as well.

The guy I bought from swears it ran fine for him on his frame. One thing Derr did to help was file back the full length ejector he originally put in my .45 wad gun; to get it out of the way of the .22LR mags.

-= Chuck

 

[Gammon]

I have the same unit with no problems now, but it did need some tweaking. Friction is the real enemy of these conversions because the 22 LR round doesn't have a lot of power and can struggle to cycle the gun.

The solution is to reduce friction as much as possible to allow the slide to function. Be careful when you mount the conversion on your 1911. Take care to have the slide properly aligned before you tighten down the guide rod to lock the conversion in place. Hand cycle the slide and feel for any excess resistance. The ejector can be a source of friction; check to see if it is rubbing against the slide. If you can locate contact between the ejector and slide, you can carefully remove some material from the ejector at the point of contact with a stone or fine file. Also, check to see if the mags are dragging on the bottom of the slide. This is not common but can happen. The solution is to remove some material from the top of the mag at the contact point. All of the above suggestions involve carefully removing a small amount of metal, leaving a smooth surface. Another way to reduce friction is to try some low viscosity oil; I prefer 0 wt or 5 wt synthetic motor oil.

The next step is to reduce the spring tension the slide has to overcome to cycle. Marvel sells reduced weight recoil springs, try the lightest. The mainspring also slows the slide down. The stock mainspring for a 1911 45 is 23 lbs. For the conversion I would recommend 17 or 18 lbs available from Wolff. These light springs should be used ONLY with the conversion. When switching back to the 45 upper, always replace the original mainspring. The springs in a 1911 are a system, replacing one will affect the others so you always want to use the springs that the gunsmith installed.

That's it. These are all the tricks I have used to get my conversions to function reliable. Any questions or doubts contact you gunsmith or Marvel. Good luck.

 

[Greg Derr]

Chuck, did you run high velocity for a while? Marvel sells lighter springs, it sounds like its short stroking. One thing I would try is to back off the torque of the guide rod, for some reason too tight causes issues. Did I put in a 17# ainspring in the .45?

 

[StevieP]

Sell the Marvel. Get an Advantage Arms target conversion. Works flawlessly on my Sig 1911, including last round hold open.

http://www.advantagearms.com/mm5/me...=AASOS&Product_Code=1911Target&Category_Code=

I got mine on eBay

 

[Gammon]

Some Marvel conversions, like the one we are discussing, are overkill for most shooting. These top ends are the equivalent of high end competition pistols and will hold their own against the best, with the added advantage of a 1911 lower that is familiar to the shooter and easy to maintain. My upper came with a test target with a group of .72 in for ten shots at 50 yds with Eley match ammo. The problem is that most shooters don't need this performance and will never spring for costly Eley ammo. I sure didn't as I use the gun for steel matches.

Part of the cost for this performance is the need for maintenance, tuning and the proper ammo. Perhaps another upper would have been a better choice, but once you have the Marvel it is well worth your while to take the time to sort it out. This is what I did and my upper is now 100% reliable with proper maintenance (simple cleaning) and the right ammo (CCI Blazer Bulk Box). I wouldn't trade it for any of the competition.