I have a Rock Island 1911 (field gun) that usually short feeds the 8th round. This happened with the factory mag as well as my shooting stars and power mags (that work fine in my Kimber and Springfield)... Is there a fix or adjustment that might help?

TIA

When you say "short feeds", please be a bit specific. Is the rd being hit by the slide? Is it failing to go into battery despite the rd chambering? Does the rd not even make it into the chamber? What exactly?

Is this a new gun? Do your 7rd mags have this problem? Have you swapped out the recoil spring yet & tried it?

Quoted: When you say "short feeds", please be a bit specific. Is the rd being hit by the slide? Is it failing to go into battery despite the rd chambering? Does the rd not even make it into the chamber? What exactly? Is this a new gun? Do your 7rd mags have this problem? Have you swapped out the recoil spring yet & tried it?

It appears to feed normally but is out of battery Bob. From a shooting stance you'd never know its not ready to fire until you pull the hard trigger on the eighth.

The gun has about 400-500 rounds through it and the GI mags (7 rounders) never have a problem.

You mention the recoil spring and I had considered trying that. Any weight recommendations on the spring? Is an 18lb about normal for a GI 1911?

Thanks...

Hi Rustytx,
16 lbs. is the stock specification.  It's a common practice to install an 18 1/2 lb. spring for reliability.  You could also try a 17 lb. spring as the 18 1/2 pounders make the slide a bit heavy to pull back.  Wolf Springs are the way to go.  Their service is excellent.

If it's just not fully going into battery, but the round is feeding into the chamber straight enough, I'd agree with the recoil spring.  Perhaps the stock spring in your gun is a little weak.  Try the Wolff springs.  They are excellent.  I've run a 20lb spring in my 1911 with no problems (racking the slide isn't THAT difficult).  

If that doesn't help, then I'd probably surmise that the angle the last round is sitting at in the mag might be tilted a little too low, thus taking more force to feed.  You may want to try to polish your feed ramp and throat.  I've used nothing but 8rd CmC mags, but given my 1911s have been Springfield, they're already ramped and throated well.  

I'm not sure I could tell a pound or two difference in the pull of the slide, but this pistol 'feels' about the same as my other 1911's so maybe a polish is the answer.

Since springs are cheap; I'll try a spring first and then maybe some ramp/throat work if it doesn't clear up.

Thanks men...

If your mag follower has that "bump" in the middle of it, the slide may lack enough energy to completely strip and chamber the round.  You could try a "bumpless" follower magazine and see if them problem persists.  It isn't a problem with the magazine per se, but it would indicate a weak recoil spring.  I run 18.5 pounders in my Gov't. 1911's.  Putting in one of these can cure an awful lot of problems.

8-round mags are inherently less reliable than the 7-rounders the gun was designed for.  You might try a Wilson 8-round mag before mucking with the recoil spring.  They're about the best around and will usually work when others fail.

Hi
  Sounds like you have got good advise .Haveing the polish job done on the ramp is always a good thing for reliability. Another thing to look at is ammo-Ball should work in any gun,as soon as you start changing bullet weight,shape,power,or overall length you are really stirring the pot.Some guns (set up right with smooth ramp,good springs.and good mags)will shoot most any ammo,a few guns will
only shoot 100% with certain ammo.
  Some time ago (when I was trying to shoot less than full power reloads for plate shoots,)I found I was draging my strong hand thumb on the slide.Someone at the time made a small metal plate, held in place by the upper grip screw.This one part made a world of difference.
  A 1911 can be frustrating as hell but when you get a good one set up right it is a wonderfull thing.   NHSPORT

Try replacing your mag spring.  it sounds like the same problem I had with my TLE.