Guidance for stack height (12 gauge)
Quote from rhodesengr on June 18, 2025, 5:01 pmIs there an actual recommended stack height when evaluating the build of different loads? What I mean is the distance from the the top edge of the uncrimped hull to the top of the shot, so actually case-length minus top of the shot from the outside bottom. I have seen different numbers thrown around, like some guys say .375". Recently while doing some online searching, I came across several mentions of "half the shell OD". That would be about .400" for 12 gauge. Seems like this is an important number but not easy to find. I understand there is some wiggle room because typical plastic wads will compress during the crimp but there must be a good target number that is likely to produce a flat crimp or be within the adjustment range of a press like the SL900.
Is there an actual recommended stack height when evaluating the build of different loads? What I mean is the distance from the the top edge of the uncrimped hull to the top of the shot, so actually case-length minus top of the shot from the outside bottom. I have seen different numbers thrown around, like some guys say .375". Recently while doing some online searching, I came across several mentions of "half the shell OD". That would be about .400" for 12 gauge. Seems like this is an important number but not easy to find. I understand there is some wiggle room because typical plastic wads will compress during the crimp but there must be a good target number that is likely to produce a flat crimp or be within the adjustment range of a press like the SL900.
Quote from The Human Manual on June 19, 2025, 3:52 pmUnfortunately, there is too much variation in fired hull length to establish a fixed dimension for this. An example; A fired STS hull I grabbed measures 2.712" long. A loaded hull overall length should measure 2.300-2.350", then subtract .065" recommended recess in the top of the hull. This reduces the OAL at the recess to 2.235" - 2. 285". So the theoretical distance from the top of the wad to the top of the open hull is .427-.477". If your recess from the lip of the loaded hull to the top of the crimp is more or less than .065" , then this is another variable. Test and readjust is the most common way, but to be at least .400" is a good starting point.
Unfortunately, there is too much variation in fired hull length to establish a fixed dimension for this. An example; A fired STS hull I grabbed measures 2.712" long. A loaded hull overall length should measure 2.300-2.350", then subtract .065" recommended recess in the top of the hull. This reduces the OAL at the recess to 2.235" - 2. 285". So the theoretical distance from the top of the wad to the top of the open hull is .427-.477". If your recess from the lip of the loaded hull to the top of the crimp is more or less than .065" , then this is another variable. Test and readjust is the most common way, but to be at least .400" is a good starting point.
Quote from rhodesengr on June 19, 2025, 4:54 pmOK, thanks. I did some digging online and didn't find too much. Your input does seem consistent the the "half the shell OD concept. My stacks are running a little lower than that. Discussion on another forum suggested that 7/16" (.437) is a good target. I am at more like .460 with my current components and get "OK but slightly collapsed crimps. My MEC 9000 gives similar crimps.
OK, thanks. I did some digging online and didn't find too much. Your input does seem consistent the the "half the shell OD concept. My stacks are running a little lower than that. Discussion on another forum suggested that 7/16" (.437) is a good target. I am at more like .460 with my current components and get "OK but slightly collapsed crimps. My MEC 9000 gives similar crimps.
Quote from The Human Manual on June 20, 2025, 7:43 pmIf your crimps are slightly collapsed in the center, then back the central plug in the top of the final crimp die up a small amount, 1/8 of a turn is all. Then retest. It won't take much adjustment to correct this, so don't overdo it.
If your crimps are slightly collapsed in the center, then back the central plug in the top of the final crimp die up a small amount, 1/8 of a turn is all. Then retest. It won't take much adjustment to correct this, so don't overdo it.