Improving the Feed Reliability of the Rock Island 52000 10mm 6″ High Cap Pro Match Pistol

As some of you may know from a previous post I did, my Big Rock would not feed Underwood 10mm ammo.  Neither Armscor/Rock Island nor Underwood helped resolve my issue though Armscor did take the pistol back and tell me there was nothing wrong with it – probably with FMJ ball ammo.

At any rate, the solution came from a discussion with my friend and FFL, Scott Igert, of Modern Antique Firearms, about the mechanics of the 1911.  A lot has to come together correctly for a 1911 pistol to work correctly.  In watching the pistol jam, I could see that it always hung on the pronounced shoulder edge of the Underwood 10mm ammo right on the edge of the chamber.

Any 10mm ammo that did not have that pronounced shoulder fed just fine.  In doing some digging, I elected to do two things.

First, I polished the feed ramp.  To do this, I fieldstripped the Big Rock and removed the barrel for easy access.

I then used my cordless Dremel with with a felt bob and Flitz polish to give the feed ramp a mirror polish.

Second, I used one of the fine rubber POLISHING tips in my Dremel to polish the edge all the way around the chamber.  To be clear, I am talking about light polishing and not removing a ton of material.  Do not use a sanding wheel or you may take off too much material in the blink of an eye.  Take your time and be patient.  My goal was to enable the 10mm case’s shoulder to slide over and into the chamber vs. hanging.  My recommendation is to always go light, test and repeat as needed.

After the polishing, I then used some of the big 10mm cleaning Q-Tips called “RamRodz” repeatedly along with visual inspection to make sure all the grit was gone and not mess up the testing.  Yeah –the RamRodz look goofy because they are huge and caliber-specific but they sure make cleaning easy.

For me, it just took one try – even I was surprised.  Whatever the case was catching on was either gone or rounded over.  The feed problem was solved – round after round cycled perfectly with no more jamming.

A few months after this I decided to sell the Big Rock to move on to other projects.  I can’t say that Armscor’s support impressed me given I had one of their top of the line pistols.  I gave them a very elaborate explanation of what was happening and they did not resolve the problem whereas a good talk with someone with a lot of 1911 knowledge, Scott, did.  It definitely shows there are benefits to having a smart friend.

In closing, I will go back to a recommendation I always make.  Before you rely on a pistol, definitely practice with the ammo you plan to use to make sure everything works the way you want.  The Big Rock liked S&B FMJ, SIG HPs and further crimped Underwoods from Scott but not the factory-direct Underwood 10mm ammo until I did the above tuning.


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