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Slide failing to cycle

Discussion in '10mm Reloading Forum' started by Special Reserve, Jan 29, 2011.

  1. I just made my first batch of 10mm reloads. Glock 20sf. I am using Montana Gold 180gr FMJ w/VV 350 powder. I started at the 5.2grains. I worked my way up from 5.2, 5.4, 5.6, 5.8, and 6.0. I shot 10 rounds of each increment. I had to manual eject the brass until I got to 6.0 grains and a couple stove piped but only 1-2 actually ejected the brass. Is my OAL the cause or just not enough power? I reload 40 and .223 and never had a problem. I always start with the minimum listed load and work my way up. This is the first time I've had the brass not eject. A few times loading 40 I had the brass just barely eject on the lightest loads. So that has me think that is the problem? Any ideas?
    Last edited: Jan 29, 2011
  2. JTknives


    Dec 1, 2009
    First off a few things to realize. People say you can load a 10mm down to 40 S&W levels but I think most that say that have never tryied it. I have and even at max 40 S&W loads the slide would barely cycle and that's with an 11LB spring. So you need to give the 10mm a kick in the pants to get things to work properly. How do your primers look and what OAL are you loading your rounds to. If it was me and I know my gun cycles fine with other ammo I would keep working up in half graines. Somthing sounds fishy but let me punch some numbers into quickload and see what kind of pressures we are looking at.

  3. I am just tossing something out there. I use a 40 conversion barrel with the same heavy recoil spring set up for the 10 and it still cycles the slide. I shoot regular wally world white box 40. if you use same load in a 10 cartridge shouldn't generate same or slightly less power and still cycle the slide? I can't imagine that the extra room in the cartridge would affect the slide that much.
  4. Never had a problem with factory ammo. I only have about 300 rounds through the gun, all federal factory ammo. All the brass went flying with the federal. Some 8-10 feet or more. I wasn't trying to load at 40 levels, just start low and work my way up. The VV reloading manual suggests 5.2 starting and 6.6 max. Primers look good. OAL 1.256. I've got a couple of other hotter powders, n105 and 3n37, but just want to get my feet wet with a whimpy one first.
  5. JTknives


    Dec 1, 2009
    Running a 40 conversion barrel will cycle the slide fine when shooting 40S&W out of it because the pressure is still up in the 30,000-36,000 range. but when you load a 10mm to 40 velocity the pressure drops because of the extra case capacity. ok some quick numbers a 192gr bullet with 9.17gr of AA#7 in a 40S&W will create 36789psi @ 1170fps. dow you put that same load in the 10mm case and you get 19746 psi at 1030fps. the pressure drops off because of the extra case capacity, you need the pressure to cycle the slide and when running a conversion barrel in 40 you still have the top end pressures.