CF-W A 9mm help/advice

[Rob1928]

I looked to no avail (my googlefu is weak) for the excellent troubleshooting threads that Coffee posted back when the M11/9 W bolts came out, so am seeking sage advice here.

I've made 4 range trips with my M11A1 and W bolt in the last week trying every possible idea I can think of and still cannot get it to function. I've clipped coils and measured every spec I can think of, tried multiple known good mags, barrels, known good factory ammo types, headspace, suppressed/unsuppressed, etc. Today I tried the latest clipped springs, shooting without the cocking knob, with no mag, etc, and it still misfires and/or locks the bolt. Out of about 80 rounds I got 1 3 round burst (1st trip) 1 2 round burst (3rd trip) and either a single shot, a shot and a jam, or most often a non-fire+locked bolt.

Here's what happens. Even putting a single round in the chamber with no mag and pulling the trigger results in a fired round about 1/2 the time and a frozen bolt with no firing about 1/2 the time. And I mean frozen. The only ways I've found to get it unlocked is to point the loaded barrel at the ground and rest the cocking knob on the edge of the bench and then put my body weight onto the back of the receiver to get the bolt to finally move. The same thing occurs when I tried it w/o the cocking knob except I would have to remove the upper and pry the bolt back to extract the live round. Not good. Extracted unfired rounds show light to no primer indentation.

I'm now suspecting that the extractor is not slipping over the rim as the round chambers and instead is chambering the round and preventing full firing pin contact. With mags inserted IF a round fired (~1:4) the result was almost always a FTE followed by attempted double feed. When I flex the extractor with a screwdriver tip the tension feels no stiffer than those on any of my other bolts. (admittedly very subjective)

Any ideas or anyone else have this issue? Is it worth it to pull the extractor and polish/contour the leading face? Could it hurt? Is it something else that I'm completely overlooking?

Any advice is greatly appreciated. I'm still very excited about what I hope is a revolutionary addition to the baby MAC and have great thanks for the people who made this possible despite any temporary fine tuning, but at this point I just want it to work.

Rob

 

[strobro32]

Sounds like a barrel alignment issue. Is the rim of a fired cartridge out-of-round or smashed on one side?

This could be a sign of a trunnion that is bent or incorrectly welded or that an upper is out of spec. In that case the barrel will not be concentric to the upper receiver. Once the cartridge enters the chamber, the rim of the cartridge will not line up to the bolt face. The bolt will jam around the cartridge rim forcing the barrel and bolt to move to one side of the receiver and jamming the bolt.

 

[Vegas SMG]

...This could be a sign of a trunnion that is bent or incorrectly welded or that an upper is out of spec..

Exactly right. It could be the front of the receiver is warped from welding in the trunnion and is pinching the bolt at the front.

You state it's a known good barrel so I'm guessing it's one you've previously used? What kind of upper are you using?

Here's the link to Coffe Freak's trouble shooting guide. Most of this applies to the A bolt.
http://www.mac-11.info/CFW Bolt Troubleshooting.pdf

 

[Hey...]

You might have to remove the barrel to see but there will be a wear pattern on top of the barrel where the bolt is sliding over. You may find a clue there especially since it's binding so hard.

Also make sure the chamber is clearanced for the extractor.

One last thing I found when getting mine to run is to look at the feed ramp. You may see the part of the bolt that strips the round from the magazine is starting to cut a shallow channel into the top of the ramp. It's touching the ramp just as the bolt is about fully seated.

I clearanced the top of my feed ramp and that finally has made my gun 99.9%

This doesn't explain the fact your bolt is literally seizing up. That I believe it's going to be a barrel issue as mentioned already in this thread.

 

[Vegas SMG]

^ Great suggestions, but most of those apply to the original CF-W bolt. The new A bolt has enough spring pressure that the small things like extractor to barrel contact and feed ramp kiss, (I had that too), won't affect function unless it's severe. I'd like to think the OP has already checked the A bolt for evidence of wear which should indicate where the bolt is sticking.

If you remove the barrel, you should be able to slide the bolt back and forth and see where the bolt is sticking inside the upper receiver.

 

[strobro32]

Another long shot is the charging knob. I had 2 of those knobs that would not sit flush in the bolt so they rubbed on the bottom of the charging knob slot in the upper. That would be easy to see by removing the bolt and looking for the rub marks.

Coffeefreak's .pdf that Vegas linked to is fantastic. They should give that way with the sale of M11s along with a link to the www.MAC-11.info site.

 

[Rob1928]

Thanks guys. I typed a long response this am but I guess it disappeared.

The upper is the stock 380 upper that is very reliable in that cal. The barrel is a 4.5" from Richard that has about 6k rounds in my max31a.

I measured the side to side alignment within the upper but not the vertical. Thanks.

Thanks also Vegas for Coffee's guide; that is exactly what I was looking for!

The charging knob is a little loose and I worried it might be rotating slightly when the bolt is forward so I shot with it removed (using a screwdriver to cock it) and the same malfunction occurred.

I'll look for rubbing on the barrel and also load a few dummy rounds for the next round.

Thanks guys!

 

[Rob1928]

Found the problem. Barrel vertical alignment!

With the barrel removed, the bolt slides freely. When assembled with an empty piece of brass in the chamber the bolt would slam forward and lock up the gun. Even the barrel couldn't be turned. Several different 9mm barrels all did the same thing, and they all spun w/o any runout in the lathe. When I'd insert a piece of empty brass in the bolt and slide it forward in the removed upper the misalignment was apparent. The chamber sits too low (if the gun were right side up), the bolt hits the case head and wedges it firmly into the chamber while the extractor gets enough grip to latch onto the now firmly stuck case.

The strange thing is the gun runs just fine in 380 even though that bolt and barrel are just as misaligned! Maybe the shorter OAL lets it navigate the "corner" more easily?
The 380 bolt does have very slightly more vertical play in the upper than the W bolt so maybe that helps it jostle into the right position too.

I'm on the baby ghost list, so I know that is the right answer, but any tips to correct this or should I just relegate this upper to 380 only?

Thanks
Rob

 

[strobro32]

I remember long ago that Richard Lage made a tool to bend the 9mm barrels for his 22 kits because barrel alignment is critical to the kit's function.

I'm not sure what his tool looked like but I used a thick walled tube to go over the barrel to gently move it while the bottom of trunnion is locked in a vice. We are talking hundredths of an inch so go slow.

 

[DINK]

As Strobro said, you need to bend the barrel slightly to move the chamber end into perfect alignment with the bolt face. It's not difficult to bend one, but it is absolutely critical to hold the assembly by the trunnion or front of the barrel and not put any pressure on the rest of the receiver because it's only sheet metal and you WILL bend it, causing a whole new set of problems. If you aren't confident about doing this yourself you should send the upper to a good MAC repair guy like Sam at Practical Solutions.

 

[Rob1928]

Thanks guys. And thanks especially for the warning about the receiver Dink! I was all ready to attempt bending my 4.5" barrel, but then thought the better of it as I plan to use that one in the Baby Ghost when it eventually arrives. I hate patience, but that's the best course, so instead I went out today and blasted a bunch of 380 in stock form.
Rob

 

[medphys]

Thanks guys. And thanks especially for the warning about the receiver Dink! I was all ready to attempt bending my 4.5" barrel, but then thought the better of it as I plan to use that one in the Baby Ghost when it eventually arrives. I hate patience, but that's the best course, so instead I went out today and blasted a bunch of 380 in stock form.
Rob

You are not going to bend the barrel. It’s way too hard for that. What you are doing is correcting the misaligned/welded trunion to the receiver tube. Stick the trunion in a vice, muscle the barrel with a large screwdriver shoved through it until the bolt closes and opens smoothly on an empty case or dummy round. If you notice and new wear or binding inside the upper receiver, get out your file.

These guns are not pristine works of art. Beat them until submission and they work and then be done with it

 

[nutinauniversalshell]

I tried aligning like above with no luck, so i sat the upper upside down on top the vise, then used hammer and wooden dowel to adjust (same sticking problem as the OP).

It doesn't seem perfectly centered but now an empty case will go right in the barrel and breech face without issue.

New issues...

1) My old go to mag...doesnt feed at all. Feed ramp probably needs adjusted as bullets contact the bottom of the barrel and stop.
2) RO PAM2 mag i never had work for 380...runs now at 20 or less rounds. More and its same as above.
(I tried to tweek the feed ramp but got nothing for movement)
3) All the ammo that ran was NEW Speer Lawman 147. Any of my reloads often had the same issue....fully chamber, bolt fully closes, no ignition on primer...barely a mark. All kinds of brass and various bullet weights.

Any suggestions?

 

[strobro32]

Wrap a few layers of masking tape on the flat surfaces of a crescent wrench an tighten the jaws around the feed ramp. Carefully pry the feed ramp up. It only take a few thousandths of an inch so go slow. Test. If the bolt makes contact with the feed ramp, you've gone too far.

Also check the feed angle of the cartridges in a 1/2 full magazine. Compare the angles ones that work with the ones that don't. The feed lips may need adjusting.

 

[Riley]

I just got my 380 upper back from Sam at Practical Solutions. I was having the same problems as Rob1928. The back of the barrel was in excess of .020” from alignment vertically. The ultimate fix was to cut the trunnion loose and reweld it in the proper position. We are lucky to have a resource like Sam that can keep these tin guns running. Now with the CFW9A bolt what a sweet little package! Clearly my current favorite! Can’t wait for the Baby Ghost.

 

[Vegas SMG]

Barrel alignment was never an issue with several different beta testers. I hate that a few of you have had this problem. I guess I shouldn’t be too surprised because alignment was covered in the trouble shooting guide for the original CF-W bolt for good reason. The W bolts are precession machined and uniform. Unfortunately, the dimensions on OEM style uppers can and do vary a number of different ways.

You're absolutely correct Riley. We’re very fortunate to have Sam at Practical Solutions, and yes, you’ll love Casper, the baby ghost. It’s purpose built for the CF-W “A” bolt and is a thing of beauty.

 

[rexifcam]

We just had a 380 upper that had such poor alignment using the CFW A1 bolt that we had to cut it apart and reweld it in the proper place. Even our barrel adjusting tools wouldn’t work and we have been using them for at least 15 years with no problems.