Commander FTRTB Issues with New Mags

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ColColt

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Took my favorite Commander to the range this morning along with two new CM mags with flat, dimpled followers and 11# Wolff springs. The second magazine with GDHP's it gave a FTRTB issue. That was with the USGI mag. I tried another new one with the same follower design and spring except this one was the Hybrid lip magazine...got the same issue with FTRTB twice-usually lacked about 1/4" closing the slide. Once the slide nearly closed and to look at it you would have thought it did but the trigger wouldn't work. I pulled the round out and tried again and it fired ok.

All the mags(2) I used were new. Could it have been that was part of the reason and I didn't load either of them up for a day or two before using them. Really, you shouldn't have to I wouldn't think but it made me wonder if they just hadn't "settled in" as yet. Ideas are welcome. I have other CM mags with these followers and springs and haven't had a problem. I did load another two mags of 7 rounds each for both mags and it didn't happen again. A third mag may have...don't know. The malfunctions were either the last or next to last round which usually indicated weaker springs but these were new Wolff springs.
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I have a Wolff 16# recoil spring in it. The other CM mags I have seem to do fine...only these last two new ones with new Wolf spring.
 
I have a Wolff 16# recoil spring in it.
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Government models use 16# springs.

Your Commander uses a 18# if it is a stock spring.

A stock mag spring is 9.5 pounds.
You have Extra power 11 pound mag springs.

That extra force pushing up on the bottom of the slide, coupled with a lighter 16# recoil spring may be causing your FTRTB problem.

I'd suggest you go back to square one with stock spring weights and see what happens.

rc
 
Why I went with the 11# Wolff mag spring was due to the recommendations from 1911Tuner in another thread I saw and also a lighter than factory recoil spring. I believe he mentioned the 16# for the Commander. Again, I don't have these problems with the other four CM mags and 11# Wolff springs, just these two new ones.
 
Tuner-I'm in Knoxville. The tension seems a little laxed to me but I've had no problems with ejection. I think it could take a little more pressure really and still not affect feeding. I need to get one of those extractor rigs from Brownell's with the tensioner and tension gauge tool.
 
Looking at it from the rear it's pretty much lined up with it's slot in the frame. I put an EGW FPS in it not long back and filed a small radius on it and then honed smooth with an Arkansas hard stone. It fits snug but not tight. I'm sure that helped keep the extractor from clocking.

When you take a 230 gr FMJ round and move it up under the extractor it seems there's little tension. As I watched the movement of the extractor it doesn't move much at all, just barely. That's why I wondered about the tension. When you said "...pushed to the right more than about .010-.012 inch..." do you mean the extractor hook itself or maybe the extractor tunnel was machined a bit too much to the right?
 
It would be hard to measure that with the equipment I have(mic and calipers). It's not much from watching it several times but I couldn't say .008" or .015". Is tension and deflection not directly related? If it has to move say .020" to hold a loaded round without it flopping up and down and falling out I'd imagine that's what it would have to be. Is there a fairly easy way I could measure it? What should it be to eliminate the problems I've mentioned-if that is the problem?

Just a last minute thought. I can chamber a round and then pull the slide back just far enoug before it hits the ejector and the nose of the round will hang down just a little-not rigid and straight with the chamber. I don't know if that tells anything or not.
 
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Is tension and deflection not directly related?
Click to expand...

No. With the correct amount of deflection the gun will tolerate a lot of extractor tension before causing return to battery problems. Conversely...with too much deflection, even light tension can bring things to an abrupt halt, especially if the bottom edge of the tensioning wall is square. Even with good deflection, a light bevel on the bottom goes a long way toward reliable return to battery. Its effect is twofold. It creates a camming surface that opens the extractor less abruptly, and it delays full tension a bit longer, giving the case rim a little running start before it hits resistance.

It's not much from watching it several times but I couldn't say .008" or .015".
Click to expand...

Remove the extractor and measure the distance between those two small, rectangular guide blocks. Then, reinstall the extractor and measure from the extractor's tensioning wall to the opposite guide block. Subtract.

This will identify or eliminate a possible source of your problem. Be careful not to let the caliper tip get into the extractor port and give you a false reading. The distance between the blocks should be about .484-.488 inch.
 
OK-side to side the glide block measurement it was .495"(plus or minus .001) and with the extractor in .485". That's .010" deflection. The extractor dropped in the recess unhindered with no resistance felt. Seems there should be some at any rate. What do you think?
 
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.495? Wow. Never ran into any that measured that wide. Are you sure?

If that's accurate, it may be a major player in your misfeeds. Those blocks are supposed to guide the rim straight onto the breechface. Since the deflection is good, that side is to spec. That means the other side is mislocated, and possibly letting the extractor kick the round sideways.
 
This is where I measured. Of course the extractor was out at the time but I just wanted to get a quick shot so you could see where I measure. These plastic RCBS calibers are not the most accurate on the marked and after measuring a few times the measurements have run from .492-.495".

I hope you can see the fine read line. I'm not the latest and greatest guru at this. Upside down gave me the best light and vantage point.

_DEF4313aa.jpg
 
If that's the case, what would be your recommendation? You can't put back what's been taken off.
 
If that's what it turns out to be, then the only real fix is a new slide. If you know anybody who has a Commander top end that will physically fit your frame, you can test it to see if the problem goes away.

It's hard to call it without actually having the gun on the bench...but you may be able to figure it out by coating the whole barrel ramp with layout fluid or a Sharpie marker, and hand-cycling a few rounds through the gun briskly several times...and taking note of where the bullet nose is hitting the ramp. If it's biased to the right side as viewed from the top...that's a strong indication that the miscut breechface is a player.

You *may* be able to carefully recontour the barrel throat on the side that the bullet nose is hitting and pushing the barrel forward...if that's what's causing the problem.
 
This sort of makes me sick. I haven't had it long...without looking at the receipt, no more than several months. I don't know anyone to speak of with another commander. I'm going to measure the two S&W 1911's I have and see what they measure. The Commander is the only Colt I have.

I measured the SW1911SC and it checked out about .492". Either it's my method of measuring, they're all larger than necessary or these plastic calipers are junk. I don't know which. I tried the Sharpie recommendation twice and it seems the bullet nose is hitting the feed ramp dead on-no favoritism toward the right. I think I'm back to square one again.
 
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Good calipers for sure. I've had this RCBS calliper for many moons but don't really trust it to be especially accurate like a mic. It's good for measuring OAL of rounds and that's about where it ends.

Harbor Freight looks to have a good one in the 6" Pittsburgh model. I guess I'll have to dig my CC out of my wallet again.

My fancy extractor gauge tool/tensioning tool is due to arrive tomorrow and I'll test the pull on the extractor to at least know where I'm at. I'm still wondering if there's enough tension since looking at the extractor it looks straight as a stick and no resistance felt putting it back in the channel.
 
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