.40 S&W with J-word bullets... Seating/crimp issues

[Animal]

Hey guys, I'm new to this type of cartridge. I understand that case tension should be sufficient to hold a bullet in place and the taper-crimp process is more of a process to remove the flare on the case mouth than it is an actual crimp (like with revolvers).

I'm loading these rounds with the Lee 3 die, plus FCD. When I seat the bullet in the case to the correct length, run it through the FCD and chamber it in the firearm... the COL decreases.

I'm using using Noslder, Hodgdon and Lyman load data. Right now, I am loading dummy rounds without powder and primer so that I can get a feel for the mechanics of this round and the function of the new die set.

Is this normal when seating to the published 'min oal'? For example, when I seat to 1.085; is it normal to eject that same round and fine that it measures at 1.079? When I cycle the same round back through it gets shorter... and shorter...[smilie=b:

135gr Nosler JHP, Starline virgin brass

S&W MOD 4013TSW 40 Tactical

[Moonie]

If you are having setback issues do yourself and those that shoot around you a favor and taper crimp those rounds. It doesn't take much setback to cause pressures to skyrocket in this cartridge.

[Hardcast416taylor]

When our local Sheriffs dept. was changing over to a .40 S&W from the S&W model 19 quite awhile back,I was on the panel that tested for accuracy and all around functioning. We found that the 165 gr jacketed rounds supplied by Federal gave the best accuracy and functioning in the Glock pistols tested. The Sheriff however over ruled our findings and went with the 180 gr. loading for better penetration of auto metal, etc.Robert

[williamwaco]

Hey guys, I'm new to this type of cartridge. I understand that case tension should be sufficient to hold a bullet in place and the taper-crimp process is more of a process to remove the flare on the case mouth than it is an actual crimp (like with revolvers).

I'm loading these rounds with the Lee 3 die, plus FCD. When I seat the bullet in the case to the correct length, run it through the FCD and chamber it in the firearm... the COL decreases.

I'm using using Noslder, Hodgdon and Lyman load data. Right now, I am loading dummy rounds without powder and primer so that I can get a feel for the mechanics of this round and the function of the new die set.

Is this normal when seating to the published 'min oal'? For example, when I seat to 1.085; is it normal to eject that same round and fine that it measures at 1.079? When I cycle the same round back through it gets shorter... and shorter...[smilie=b:

135gr Nosler JHP, Starline virgin brass

S&W MOD 4013TSW 40 Tactical


The "Correct length" is the length that works in your firearm. Not some number you pulled from a manual.
the ejected round should not be shorter than when it was chambered. This means part of the energy from the recoil spring is being used to seat the bullet deeper. Sooner or later that slide is not going to close into battery. I sure hope it is not at a "crirical" moment.

[Animal]

I spent a good bit of time experimenting with seating depth and taper crimp last night. No matter how short I make the round, it continues to eject from the chamber at .005 shorter than originally made. I examined the bullets under a lamp for any indication that it is seating against the rifling, none can be found.

After trying every combination of case tension and seating depth that I could think of, I cycled a few factory rounds through the chamber and found that they also eject at approx .005 shorter than the original oal.

[williamwaco]

I spent a good bit of time experimenting with seating depth and taper crimp last night. No matter how short I make the round, it continues to eject from the chamber at .005 shorter than originally made. I examined the bullets under a lamp for any indication that it is seating against the rifling, none can be found.

After trying every combination of case tension and seating depth that I could think of, I cycled a few factory rounds through the chamber and found that they also eject at approx .005 shorter than the original oal.


Perhaps the "seating" is occurring when the cartridge hits the feed ramp?

[TXGunNut]

Perhaps the "seating" is occurring when the cartridge hits the feed ramp?

Could be, I've noticed the same thing. Maybe a little ramp polishing is in order, can't hurt.

[Animal]

I've been researching this lately. Apparently it isn't all that uncommon even with properly sized boolits. I've found a few reports about police officers having feed issues with the rounds that they cycle through the chamber on a regular basis. Since they usually keep the same round in the chamber, many will cycle it through the action one or more times a day. After a good bit of time goes by, the round gets short enough that it won't cycle properly. "Bullet setback" is what they are calling it.

I asked a buddy of mine to see if he could replicate the phenomenon with his 1911... sure enough, he had similar results. I then tried a 3rd type of ammo (factory) and got similar results again. I'll provide some links to a few articles when I get home.