10mm Woes

[Rmeju]

I have a 10mm 1911 with (what I think is) a tight chamber, and it was regularly having 3-point jams with 180gr RN-FMJs at a 1.260 COL. After asking around, I got a suggestion to load them shorter to fix the feeding problem. It did... sort of.

I loaded about a hundred at 1.245 COL, but this made me a little nervous about pressure. They seem to feed fine now, but I cycled them through (dropped the slide on a couple mags, one by one) and then remeasured them to see if the feeding process was shortening them even more, and they're coming out around 1.235 COL, some even less.

My question is: should I be worried about pressures at these shortened lengths? I'm using book-listed powder charges (not max, more like low-mid) for 1.260 COL. If this is a problem, what can I do?

Thank you!

 

[GaryL]

What are you using for powder? Being on the low side of mid is going to help with managing pressure.

The COL for lighter/shorter and longer/heavier bullets is the same, so the 180s are taking up some of the empty case compared to 155gr bullets, and the powder selection and charges will account for that.

0.025" isn't a lot in my mind, but I would look at the loads for 200gr, and see if you are below max with those - that would give you some margin to work with.

 

[Steve in Allentown]

In the future you might try doing the manual feeding test without the recoil spring being in the pistol. Just put a thumb on either side of the back of the slide and push forward just hard enough to push the cartridge out of the mag, fully into the chamber, and the pistol into battery. It should keep the bullet from being pushed so far into the case. It also allows you to feel every bump in the mechanism as the bullet makes it's way forward.

I use this technique after finishing a build but prior to its first range test. It allows me to catch things that I can't during live fire and iron them out before blowing rounds down range.

 

[Rmeju]

What are you using for powder?

0.025" isn't a lot in my mind, but I would look at the loads for 200gr, and see if you are below max with those - that would give you some margin to work with

Thanks Gary, I'll take a look. I've been using Unique for my main plinking powder. The Hornady manual lists 6.4 gr as the max for 200gr, which is exactly the mid-point for 180gr. So, maybe I should be ok as long as I make that my limit.

Also, hi from Minnesota.

In the future you might try doing the manual feeding test without the recoil spring being in the pistol. Just put a thumb on either side of the back of the slide and push forward just hard enough to push the cartridge out of the mag, fully into the chamber, and the pistol into battery. It should keep the bullet from being pushed so far into the case. It also allows you to feel every bump in the mechanism as the bullet makes it's way forward.

I use this technique after finishing a build but prior to its first range test. It allows me to catch things that I can't during live fire and iron them out before blowing rounds down range.

I will give this a try and report back on where the hangup is. Maybe that will give me some info on where to go with it.

Thank you both for the replies!

 

[rfwobbly]

The setback issue makes it sound like you may have several issues going on...

• I'd check first on the diameter of the expanded case. It should be 0.002 - 0.003" smaller than the bullet, so that the seated bullet is held tightly.
• Then check your taper crimp diameter to make sure it matches the diameter of the case. It should be pretty much one diameter along the full length of the case. Too much Taper Crimp can loosen the bullet, because the case buckles ever so slightly.

My question is: should I be worried about pressures at these shortened lengths?

Chamber pressure is all we ever worry about, so 'Yes'. Try to find published data using an OAL shorter than what you're using. If you cannot find that data, then you'll need to use a chrono to reconcile the pressure issue via bullet velocity.

Hope this helps.

 

[TonyAngel]

The setback issue makes it sound like you may have several issues going on...

• I'd check first on the diameter of the expanded case. It should be 0.002 - 0.003" smaller than the bullet, so that the seated bullet is held tightly.
• Then check your taper crimp diameter to make sure it matches the diameter of the case. It should be pretty much one diameter along the full length of the case. Too much Taper Crimp can loosen the bullet, because the case buckles ever so slightly.



Chamber pressure is all we ever worry about, so 'Yes'. Try to find published data using an OAL shorter than what you're using. If you cannot find that data, then you'll need to use a chrono to reconcile the pressure issue via bullet velocity.

Hope this helps.

Yes, this above. If you’re getting setback like that it’s either too much crimp or not enough. Are you seating and crimping in one station? You should have a set of calipers to verify the diameter of the cases of loaded rounds.

As for whether you’re gonna have a pressure problem, that depends on your load.

 

[GaryL]

Thanks Gary, I'll take a look. I've been using Unique for my main plinking powder. The Hornady manual lists 6.4 gr as the max for 200gr, which is exactly the mid-point for 180gr. So, maybe I should be ok as long as I make that my limit.

Also, hi from Minnesota.

Interesting - my Hornady manual has 5.9gr Unique listed as max for 200gr bullets - you might double check that. My manual is over 20 years old, so not saying things haven't changed. And my Lyman manual is more generous with Unique as well.

I agree with the others who suggest you figure out the setback issue. You could also try using a Wilson case gage to see if your rounds are properly sized, which isn't going to help with a short leade, but you can use it to check cases after resizing. The only time I've really had an issue with cases failing to hold a bullet (setback) was with some WWII 45acp cases I was reloading. Being cheap, at the time, I set those aside to load with Missouri Bullets cast product. They have a groove right at the case mouth, and the taper crimp was enough to catch the groove - no more setback, and they feed and headspace perfectly.

 

[Jack Ryan]

Run a few through a Lee factory crimp die and the manually cycle them a couple times. I bet they'll be tighter.

Don't bell out the mouth any more than you HAVE TO, to get the bullet started in the case.