rupie Posted May 27, 2011 Share Posted May 27, 2011 I discovered something and I am wondering what your experience is, I got a bunch of reloads from a friend when i bought his gun from him. The bullets didn't seem like they had as much crimp as i am used to putting on my 40's so I took 10 and re crimped them and then shot 10 of each over my chrono. His measured roughly .421 mine .417 on his you can just barely see what looks like a gap (shadow?)between the brass and bullet. Mine is closed tight. When i crono'ed them there was in the neighbor hood of 40 fps difference between the 2 crimps? That got me wondering, is my crimp to tight? Link to comment Share on other sites More sharing options...
pjb45 Posted May 27, 2011 Share Posted May 27, 2011 I use a Lee FCD. I use it for reliability in my feeding. That is the only reason. I would start with what makes for the most reliable feeding as the critical success factor and adjust my powder accordingly. Link to comment Share on other sites More sharing options...
dugout Posted May 27, 2011 Share Posted May 27, 2011 I use a Lee FCD. I use it for reliability in my feeding. That is the only reason. I would start with what makes for the most reliable feeding as the critical success factor and adjust my powder accordingly. How does it improve reliability and feeding? Link to comment Share on other sites More sharing options...
rupie Posted May 27, 2011 Author Share Posted May 27, 2011 I will assume he is talking about how the cartridge interacts with the feed ramp, and the possibility of bullet setback from a weak crimp. Link to comment Share on other sites More sharing options...
Jman Posted May 27, 2011 Share Posted May 27, 2011 is my crimp to tight? Yes. "IMHO" There really is no 'crimp' used on 9 and 40's. We're just removing the flare (bell). Case tension is all that's wanted. If you measure your bullet (example .400 for jacketed 40 S&W) and your brass ~.022 = .422 So..snug (for me) would be something like .420 using the above components. As far as a die is concerned the simple taper crimp die from Dillon has out shined them all (for me) in both 9 and 40. Jim Link to comment Share on other sites More sharing options...
dugout Posted May 27, 2011 Share Posted May 27, 2011 I will assume he is talking about how the cartridge interacts with the feed ramp, and the possibility of bullet setback from a weak crimp. Well the bullet contact with the feed ramp is more of a mag tuning issue but I'm willing to learn. I like .420 at the case mouth with a simple Dillon tapper crimp die, just bringing the case back into form. .400 bullet and .010 case thickness. Link to comment Share on other sites More sharing options...
gng4life Posted May 27, 2011 Share Posted May 27, 2011 I have mine at .420 also with my Dillon die and never any issues. Same with my 9mm, I have them at .375. However, it also depends on brass, especially range brass. Taking it down to .417 is a little too tight for my taste. Remember it headspaces on the case mouth so it's not a good idea to get it too tight. Link to comment Share on other sites More sharing options...
rupie Posted May 27, 2011 Author Share Posted May 27, 2011 I have mine at .420 also with my Dillon die and never any issues. Same with my 9mm, I have them at .375. However, it also depends on brass, especially range brass. Taking it down to .417 is a little too tight for my taste. Remember it headspaces on the case mouth so it's not a good idea to get it too tight. I dont know what that means can you explain and educate me to what it is and why its important. Link to comment Share on other sites More sharing options...
EkuJustice Posted May 27, 2011 Share Posted May 27, 2011 The cartridge does not have a rim like a revolver so how far it seats in the champer is off the front of the brass not the rim like in a revolver. Its the same reason you don't shoot 40sw in a 10mm even though the 40s can be loaded to 10mm length Link to comment Share on other sites More sharing options...
rupie Posted May 28, 2011 Author Share Posted May 28, 2011 That is interesting i had no idea how a guns head space came to be, although I have heard that term for years Link to comment Share on other sites More sharing options...
kamikaze1a Posted May 28, 2011 Share Posted May 28, 2011 I too would say .417 is crimping too much. Question though, you said 40fps diff so I assume that your crimped clocked slower than the no crimp? How was the SD? I have found that a proper crimp give my reloads more consistent velocity and in most cases, more consistent accuracy... Link to comment Share on other sites More sharing options...
rupie Posted May 28, 2011 Author Share Posted May 28, 2011 I didnt record the SD but you were correct more crimp slower velocity Link to comment Share on other sites More sharing options...
RobfromME Posted June 8, 2011 Share Posted June 8, 2011 I overcrimped some plated bullets in 40S&W and ended up with keyholes at 10 yds. After re-adjusting to just remove the flare, everything works as it should again. There's been no problems with bullet setback either. I've checked by pushing on the bench and also after the slide chambers them and they're fine...no change in OAL. Warmest regards, Rob Link to comment Share on other sites More sharing options...
gng4life Posted June 8, 2011 Share Posted June 8, 2011 I overcrimped some plated bullets in 40S&W and ended up with keyholes at 10 yds. After re-adjusting to just remove the flare, everything works as it should again. There's been no problems with bullet setback either. I've checked by pushing on the bench and also after the slide chambers them and they're fine...no change in OAL. Warmest regards, Rob Did you take any measurements before and after? I have a friend and he is experiencing the same as you did with the same bullet. He swears his crimp is right but I don't think so. Thanks... Link to comment Share on other sites More sharing options...
RobfromME Posted June 9, 2011 Share Posted June 9, 2011 Good morning, gng4life, I didn't take a before measurement. However, the taper crimp was so much that you could actually see that it was depressing the sides of the bullet. It was really over done. When I reset the crimp die, I crimped only until the neck measurement matched the manual; I believe it was 0.422" or 0.423" (I'm at work so I can't say for sure). Once I reached the measurement, I made sure that it wasn't deforming the bullet. Everything was fine from then on. It was amazing how much different the performance was...8-10" keyhole groups at 10 yds when overcrimped and 3-4" groups at 25 yds (from bench) when crimped as noted above. Hope that helps. I initially blamed the bullets and bought some regular jacketed bullets, but my blame was misguided. I should have known better since plated bullets had served me well for a long time. Warmest regards, Rob Link to comment Share on other sites More sharing options...
gng4life Posted June 9, 2011 Share Posted June 9, 2011 Thanks, that about what it should be for most loading, most of mine are between .420- .422 but I use jacketed bullets now with range brass. I've never had any problems with keyholing but I've seen it lots of times. Thanks for the info... Link to comment Share on other sites More sharing options...
SteveU Posted June 9, 2011 Share Posted June 9, 2011 I use Zero JHP. I crimped to .422 but had some trouble with chambering. I tightened crimp to .420 which really ended up being .419. Chambers great, deforms the bullet slightly (ring), but no keyholing. Link to comment Share on other sites More sharing options...
shooterbenedetto Posted June 9, 2011 Share Posted June 9, 2011 I take a factory bullet, measure it and andjust mine as a reference. Link to comment Share on other sites More sharing options...
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