This is NOT a BRAG or a GRIPE. I probably shouldn't even type this.

JUST an OBSERVATION. I have been reloading 10mm ammo for a couple years. I've never had a round fail to feed or otherwise hang up. During this same time I've had plenty of Sig ammo jam up. Enough Underwood to be uber irritating. Plenty of local reloading companies. I would say I shoot more reloads than bought ammo so it's not just a numbers game.

When I mic these rounds (I was hopeful at first) - nothing stands out as largely different. BUT when I look closely (side view in an optical comparitor for example) some such as the Sig 180gr, have no crimp and  in fact the case appears to have a bell mouth. I have run several boxes of Sig through the my Lee FCD and they run much smoother, but still not perfect.

I always use a FCD. I use a normal (not undersize) die. I try like a madman to keep my OAL consistent but it varies. But what the heck?

This is not a knock or a shot .... but im guessing that, given your admitted "varying OAL", amongst likely other varying dimensions, your 100% track record with personal handloads versus your reported (substantially) less reliability with Sig and Underwood factory ammo, that the cause of your observed differences in overall reliability might likely be attributed to .... luck.



Stay safe!

True enough.

My OAL doesn't vary that much, but I'll record some numbers next time. I just know every round I make is not exactly 1.260", for example. 1.263", 1.261", 1.262" type of thing.

Gun?

My G20 eats everything (stock & LW) EXCEPT 155 & 175gr SWC. NO oal can get them to feed 

Quote from: Benchrst on January 06 2017 11:18:52 PM MST
Gun?

My G20 eats everything (stock & LW) EXCEPT 155 & 175gr SWC. NO oal can get them to feed 

A couple Glock 20's. My 20L (LW super tight chamber) chokes on SIG ammo all day long. Chokes regularly on S&B and Underwood. Others it just jams at irritating times. My ammo? Smooth as  silk.

My 10 mm AR SBR is a choke master on anything. Except my full power home loads. For sure it needs those "+P" loads to cycle but Sig can't even make it in the chamber.

My 1006 eats everything and anything for years. Feed it Sig 10mm and it hangs.  Run that Sig through the Lee FCD and like butter.

Measure all of the different types of ammo at the case mouth...

That'll tell you if they're properly crimped or not... You're looking for .423".

Well there is a reason that comes to mind...FCD   This die can actually squeeze the bullet down if the brass is on the thicker side.  If that happens the bullet gets slightly longer.

One of the reasons for a good taper crimp is that it helps smooth out the transition at the end of the case mouth and that helps feeding more smoothly.  There is a fine balance to crimping and brass can be different thicknesses and lengths which can also change Cartridge Overall Lengths slightly...

The best thing I learned with loading for the 10mm, was seating and crimping is separate steps.  LEE's FCD was best used for pass through sizing purposes.  I originally purchased the FCD as a final crimp die, but quickly found that my bullets got loose after that process.  I could turn the bullet as crimped inside the casing with some showing movement in and out, due to the bullet being squeezed down.   

My old original RCBS 10mm dies were such that they too long inside and wouldn't properly crimp the shorter 40S&W.  I later purchased a 10mm/40S&W seater die so I could get better taper crimps on the 40S&W.
The taper of my Original set is longer inside but the die would hit the shell holder and still not reach the 40S&W.  When seating bullets for 10mm I would have to place a 1/8" thick spacer to raise the die enough to prevent any crimp while seating...

Quote from: Ridgerunner665 on January 07 2017 07:00:52 AM MST
Measure all of the different types of ammo at the case mouth...

That'll tell you if they're properly crimped or not... You're looking for .423".

I think it's more subtle than that. There are some that are .422", and the case mouth is more abrupt, the bullet is at minimum material condition - it will hang.

Quote from: The_Shadow on January 07 2017 07:58:37 AM MST
Well there is a reason that comes to mind...FCD   This die can actually squeeze the bullet down if the brass is on the thicker side.  If that happens the bullet gets slightly longer.

One of the reasons for a good taper crimp is that it helps smooth out the transition at the end of the case mouth and that helps feeding more smoothly.  There is a fine balance to crimping and brass can be different thicknesses and lengths which can also change Cartridge Overall Lengths slightly...

The best thing I learned with loading for the 10mm, was seating and crimping is separate steps.  LEE's FCD was best used for pass through sizing purposes.  I originally purchased the FCD as a final crimp die, but quickly found that my bullets got loose after that process.  I could turn the bullet as crimped inside the casing with some showing movement in and out, due to the bullet being squeezed down.   

My old original RCBS 10mm dies were such that they too long inside and wouldn't properly crimp the shorter 40S&W.  I later purchased a 10mm/40S&W seater die so I could get better taper crimps on the 40S&W.
The taper of my Original set is longer inside but the die would hit the shell holder and still not reach the 40S&W.  When seating bullets for 10mm I would have to place a 1/8" thick spacer to raise the die enough to prevent any crimp while seating...

Interesting and excellent information.

Doing the documentations has shown crimps at the edge being all over with some down to 0.4180" and some as 0.4235"

Underwood and Starline cases have measured 0.4215" at the base and the crimps for UW have been 0.4215" - 0.4225".  These are fairly consistent with brass case lengths varying very slightly as well.  Adv. Length 0.9870"  spread is 0.9865" - 0.9880"

IC sent some Re-Man ammo that would not chamber because they were severely over crimped...
Crimp Diameter 0.4135" / 0.4120" / 0.4120" / 0.4120" / 0.4120"  (tight)

Wow!!!!

I taper crimp all my auto pistol ammo in a seperate operation with Lee die on the Dillon. Works great.

Well POOP. It had to happen. My first feeding failure with a homeload. Cause currently unknown. I marked the round after the first  time and put it randomly in a magazine and did the same stoppage two more times. Will measure and see what is up.

It's amazing how things jump out on an optical comparator.

I've used one at work a few times to check out cartridges and solve handloading problems.

I taper crimp my handloads .421-.422 at the mouth and my Glock 20 Gen 3 with KKM barrel & 20 lb Wolff spring feeds em 100%, but several types of Underwood blows primers totally out of the case and fails to chamber every other round anyhow.

Underwood ammo from the same boxes ran 100% with no issue other than a few smiles in my Glock in stock condition.

I suspect the brass was burred on the inside of the case mouth, or something prevented a good crimp. It's around 0.424-0.425"

Wish I had and optical comparator.