Crimping a bottleneck pistol cartridge

chemo

chemo

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Since I've began working on 400corbon I've had some fun days some others pretty grim.

The slipping of the bullet can be as much as 0.020'' when I chamber a dummy round:eek:
I have screwed the Lee seater furter, as per their instructions, to create some crimp and just removed the case expand station, but I still get 0.009'' of slip. Impossible to add more crimp with the seater as the shoulder just gets crushed.

I've been trying to solve the slipping problem of this cartridge since last night to no good. I'm still waiting for a factory crimp die to show up, but I got a hard time beleiving it'll solve the problem. Some suggest a roll crimp is stronger than any taper crimp. This, I do not know first hand because I have just taper crimped and it always worked (with other cartridges)


What do ya think?
 
A roll crimp from the lee factory crimp die will solve your problem. When I taper crimp, I generally unscrew the bullet seating lug very far to avoid accidental OAL changes.

What kind of expander die are you using. Is it adjustable? Perhaps the neck is expanding too much.

Are you FL sizing, or just neck sizing.
 
-OAL is fine, until I chamber a round. Though the FCD will taper crimp, not roll, not sure if that was a typo in your post

-so far I was using the powder through expander die that came with the LEE 3 die kit. But I just received the dillon 40cal powder funnel to adapt my powder charge so I was about to upgrade to that, keeping case mouth expension at a minimum. So, expension was minimal but now I just skip it, I just take more time holding the bullet till its in the die, but the bullets still slip...

-It is a FL sizing process
 
I guess I misread your problem. I see now that the issue exists when the bullet is pushed into the case by the throat. The crimp isn't holding when the round is chambered.

I've always called the crimp done by the Lee FC die a roll crimp because the lip of the case is turned in when the crimp is done. Maybe I've been calling it the wrong thing all this time. In any event, the lip is depressed much more snuggly than by a standard taper crimp die - to the point that you can deform a hard lead bullet and create an artificial crimp groove.

Your problem seems to stem from the crimp not embedding firmly in the cannelure (if you're using jacketted bullets) or perhaps the gnurling of the cannelure is too positively relieved for the crimp to compress it and form a tight seam.

If you measure with calipers the outside diameter of the cannelure, is it the same size as or slightly larger than the bullet just above the cannelure? This can happen if the gnurling tooling is dull and/or hot and would cause the issue. If that's the case, I'd blame the bullet manufacturer - it's probably a bad batch.

Of course there's the possibility that the issue is the chamber. What happens if you seat a very lightly crimped (no powder) cartridge and bullet by hand, does the bullet push into the casing? I'm not familiar with the spec of the .400 corbon but in many cases, such a throat would be considered too tight. It could also be caused by an imperfection in the chamber near the throat.

Just out of curiosity's sake, where did this bbl come from and what sort of bullets are you using? Did you start with .45 acp brass and work the neck down or are they commercially produced.

One final thought is that if you've necked down .45 acp brass using some sort of progressive technique, it's possible the brass is too thin.
 
I bought a Lee Factory Crimp die in .400 CorBon and have had no problem with it at all. I have been using both .400 CorBon brass and necked down .45 Super brass.
 
Garand said:
I bought a Lee Factory Crimp die in .400 CorBon and have had no problem with it at all. I have been using both .400 CorBon brass and necked down .45 Super brass.
Click to expand...

did you previously had problems with the bullets slipping in?



@bigslide:
storm lake barrel
cam-pro plated bullets (no cannelure of course, that's why I want to taper crimp)
resized 45acp
 
Well f**k me, the FCD did not good, still getting .015 to 0.030'' of slip. And the FCD is set to an hardcore crimp AND the recoil spring is a low #13, I mean, how much more attention can I put in there FFS :mad:

With OAL 1.225'' the lowest it will go is 1.188'' (upon at least 5 chamberings)
Tried different kinds of brass, my newest Starline brass being the worst of the lot with the 0.030'' of slip.
 
Have you tried a very light crimp? I've found that very heavy crimps can end up with less neck tension, probably because the brass case will spring back a little after crimping, but lead doesn't, so you end up with less neck/bullet contact area.
 
Try not crimping at all. See how much neck tension you have got. I have found that if the brass is decent u will find that neck tension is pretty strong. This is with 30-30 and 270. And all my pistol cases. I use the lee fc die and put a pretty light crimp on everything other than the 30-30 as its a tube mag.
 
my first post was for uncrimped rounds, so no crimp is no good.

I guess I'll try light crimp now...
EDIT: oh well, light crimp didnt help at all, I guess I'll just go blow myself up, anyway I'm softloading and will use the spring number according to the right power.
 
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C.E, I am not familiar with the .400, so could you explain the dies you are using. Does the sizing die have an expander button? If so, what doe it mic at? What bullets are you using? Cast, jacketed? Is there a cannelure on the bullets? Are you crimping the case mouth into the cannelure?

Many questions. Any photos?
 
When reloading any cartridge you should have enough neck tension to hold the bullet against your body weight, and crimping just gives a bit extra so bullet doesn't jump under recoil. Crimping will not make up for insufficient neck tension, you need to go back to square one and get a smaller (proper size) expander and/or use a bigger bullet, which is not always possible. It's been said many times that the case neck must be .002-.003" narrower then the bullet before seating.
The .400 Corbon has a very short neck and this will add to your problems, another old rule is that case necks should be more then 1 caliber long, your's is not!
 
I agree with the last two posters. Crimping isn't going to solve your problem if you're getting that much bullet slip. I add just a touch of a roll crimp on my .357Sig rounds, just enough to get rid of the bell. Neck tension alone holds the bullets in place, and not unlike your .400 CorBon, .357 Sig have very short necks.
 
what I really dont understand is that I'm running the same setup as Garand does, yet he doesn't have any problems
 
-I use brass from many lots

-bullets are normal .401'' 40cal projectiles from cam-pro as previously stated.

-I do not expand the case at all (yes ben, the case is 0.002 narrower)

-the sizer has no expander ball

-no case lube is used as I presize with a 45acp die


you mention neck tension this and neck tension that, but at this point what can I do about it? Design flaw that I'm the only one experiencing maybe? Buy new dies?
My last atempt will probably be at +P brass, and thanks all for all the support, it is very appreciated. That'll teach me to try and have fun. Boring old calibers are the way to go, lesson learned!
 
charles.emond said:
Boring old calibers are the way to go, lesson learned!
Click to expand...
Wrong lesson!

Is there any way for you to determine whether the bullet's setting back from hitting the feeding ramp or from the throat being too tight (if you simply drop a loaded round in the chamber, does it go all the way in)? Once the bullet has set back, have you tried feeding it again and again to see if it sets back even more?

I may be wrong, but the way I figure it, if it's the throat pushing the bullet back, you could simply seat the bullets a bit lower. What happens when you put a loaded round bullet-down on a tabletop and push down on it with all your might? Can you get it to move?
 
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