What causes 3-point-jam FTFs?

[Slowmo]

My M11 is having trouble with 3-point-jam type failures-to-feed where the bullet is contacting the top of the chamber, the case is contacting the bottom edge of the chamber not far behind the case mouth, and the casehead is contacting the bolt. Some of the time, the bullets are getting set back into the case. In jammed cartridges, I notice that there is a crescent groove impressed into the case from where it hits the chamber mouth and a scuffed or maybe even slightly flattened spot on the bullet on the opposite side.

Possible things I can think of:
-COL is too short so cartridges are entering the chamber at too steep of an angle?
-Something keeping the casehead from smoothly sliding up the boltface?
-Edge of the chamber is too sharp?

To the degree relevant, it’s happening with an FTF CNC bolt and a PS Baby Ghost upper. I tried three different types of mags with same problems.

 

[Offmarksman]

Sounds like the magazine may sitting too low? Get some snap caps (DO NOT use live rounds) and hand cycle. Maybe push in on the mag while hand cycling, and see if that makes a difference.

 

[root]

What type of ammo ? Reloads or factory and if so details on factory ammo
also what mags?
Probably more important then the ammo not all mags are equal.

And I'll second playing with mag hight if good quality mags are being used.

 

[Slowmo]

The ammo was CCI Blazer brass 95gr FMJ.

It is a small grip M11. Magazines were a:
-CMP marked mag (my impression is that these were the factory mags from the RPB/SWD days),
- one of the recent RPB magazines sold by PS that has the plastic follower and separate metal plate welded to the back seam near the top, and
- one of the most recent RPB magazine batches with a metal follower and no plate on the back seam.

The two more recent RPB magazines barely rubbed the bolt (I cleared them with the same procedure used for Shockwave mags), which makes me think they couldn’t sit much higher without substantial interference with the bolt.

 

[A&S Conversions]

How old is your recoil spring? I am guessing that once upon a time, this problem didn’t exist and has increased in frequency over time? What you have described certainly sounds like the mags are a little too low and/or the recoil spring is a little bit weak.

Also I would look inside the chamber. Is there any roughness? A little polishing compound and a fiber tip with some light polishing might help?

Scott

 

[strobro32]

I have not had luck with M11/9 or M11A1 bolts from FTF. The recoil springs are too stiff.

 

[Slowmo]

The FTF bolt and recoil spring are both more or less brand new. I bought it thinking I’d set aside the original cast bolt to preserve its condition.

I could swap a recoil spring from PS into the FTF bolt assembly or could try the original cast bolt.

Are three-point jams a symptom of the spring being too strong or too weak?

 

[strobro32]

Yes. If the bolt does not recoil enough to completely clear the cartridge, it can produce a FTFeed.

 

[nklf]

my suggestion would be to try the original bolt and spring. If that works then try the original spring on the FTF bolt and see if that works. It always a good idea to only change one part at a time. I have an M10 that is so out of spec it will not run with any modifications, but it runs like a sewing machine when I put all the original to me parts back in.

 

[Slowmo]

Yes. If the bolt does not recoil enough to completely clear the cartridge, it can produce a FTFeed.

Unfortunately I don’t think that was my problem here because it was happening over and over again firing from semi-auto where the bolt was starting off being released by the sear. Now that you mention it, I have had that issue with some weak .45 in my M10 though.

 

[Slowmo]

my suggestion would be to try the original bolt and spring. If that works then try the original spring on the FTF bolt and see if that works. It always a good idea to only change one part at a time. I have an M10 that is so out of spec it will not run with any modifications, but it runs like a sewing machine when I put all the original to me parts back in.

Does the cast M11 bolt require the barrel to be notched for the extractor? My understanding is that the M10 cast bolts require a notch to clear the extractor.

 

[LawBob]

I’m confuse bc ftf is a brand and an abbreviation for fail to feed

 

[Slowmo]

I’m confuse bc ftf is a brand and an abbreviation for fail to feed

I’m getting failures to feed with my FTF-brand bolt.

 

[man9mm]

Here are a few possible solutions to try:

Adjust the Cartridge Overall Length (COL): Too short COL can cause the cartridge to enter the chamber at a steep angle. Try adjusting it to see if it helps.

Check the Boltface: Make sure there's no debris or any issue preventing the casehead from sliding smoothly. Clean and inspect for any possible irregularities.

Inspect the Chamber: A sharp chamber edge could potentially cause these issues. Consider getting the chamber checked by a gunsmith a if needed.

Test your M11 after trying each step to see if it resolves the issue. Good luck!

 

[Slowmo]

I got some of the AZoom aluminum snap caps in the mail today, and they cycled just fine by hand in all three mags that I tried before. Very encouraging. At least at slow speed, the mag lips seemed to be doing a pretty good job of guiding the bullet towards the chamber. Interestingly, the snap caps seem to have a slightly shorter COAL, which at least in my experience is more of a cause than a cure for this type of jam.

I also got four different types of ammo in the mail, so we’ll see. I’ve also got everything needed to reload for .380 but wanted to make sure this setup runs OK with factory ammo before I start introducing even more variables through reloading.

 

[fortyfive1911a1]

I’d recommend trying some S&B ammo if you haven’t yet.