Seating depth & Roll Crimp question

[Ace25]

Hello,

I'm new to posting to this board, but have been "lurking" for a while. I have reloaded tons of rifle rounds & just got my first set of pistol dies for a .357 mag / .38 special. (I had to do a bit of research on crimping...)

The two .38 rounds I loaded have the same crimp just a different seating depth.

My questions:
1. is this sufficient crimp for a .38 load (do I want more or less?)
2. how about for a .357 max load, do I want more crimp or about the same?
3. lastly, seating depths - I'm open to opinions on this.

Below are 2 pics of the first rounds I loaded, the top is seated slightly more than the bottom.

 

[Walkalong]

Those look very good.

 

[buck460XVR]

Looks like more than enough crimp for .38 and should work for even the most robust .357. The round that is seated deeper looks most like how I seat jacketed bullets. Some cannelures are narrow, so crimping into the middle means there is not much cannelure left exposed. But depending on whether or not you trim your brass or how close to the same length your cases are, you may get rounds from the same batch that look like both.

 

[Vodoun da Vinci]

Not to horn in on yer thread, Ace, but I just started working on my first round of .38 Specials in about 30 years so I'm gonna jump in here if you don't mind and ask a question as well....

What are folks thoughts about taper crimping on .38 Specials? I have a set of RCBS dies that do a sweet job on seating/roll crimp with a round nosed bullet but I'm wanting to load RNFP lead now and will load some hollow points as well soon. My existing seating/crimping die makes a mess of the flat pointed bullets and I'm not gonna load any round noses so I need a new seating die anyway.

I never used to load automatic ammunition and bought taper crimp dies from CH4D for my .32 ACP and 9mm. Can you/should you taper crimp a .38 Special? Some of the bullets I'm gonna use do not have a band to roll crimp into and I just kinda like the concept of taper crimping and thought if I'm buying a new seating die and stem for flat noses I can get a taper crimp die at the same time.

Thanks in advance. By the way, Ace, yer roll crimps look great!!

VooDoo

 

[gamestalker]

You can use a taper crimp, as long as the bullets aren't jumping up. If you do nothing more than remove the bell use during seating, and your bullets are staying put in the case mouth, then you are good to go.

Personally, I crimp all wheel gun cartridges, but I also load some stout stuff too.

GS

 

[Jim K]

Taper crimps are used for cartridges that support ("headspace" if you will) on the case mouth. You don't want a roll crimp on a 9mm Luger or a .45 ACP because the case won't have a solid support point at the chamber shoulder and you can get inaccuracy at best or misfires at worst.

The taper crimp ensures that the case mouth is not rounded over and will stop solidly against the chamber shoulder. The .32 ACP, however doesn't need a taper crimp, since it is supported on its rim, not on the case mouth.

Jim

 

[buck460XVR]

I taper crimp plated bullets in .38 special. Works just fine as long as you have sufficient neck tension.

 

[el indio]

I crimp all my revolver loads with Lee factory crimp dies and have had no problem with a bullet set back. I also use them for my rifle rounds.

 

[cfullgraf]

I taper crimp plated bullets in .38 special. Works just fine as long as you have sufficient neck tension.

I do this as well with 38 Special. Also, i taper crimp my wadcutter loads because I am too lazy to set up the roll crimp die. FYI, I crimp in a separate step, old habits die hard.

I just remove the mouth belling with the plated and wadcutter bullets.

 

[James2]

In your first picture, I like the one that is seated the deepest. For my tastes, I would seat them a bit deeper yet. I like to see about 7/8 of the the cannelure covered with brass. Personal thing, likely has no bearing on anything else. How much crimp? Just enough to keep them in place under the recoil of the piece.

If you are not crimping into a groove, taper crimping, just put enough on it to press the brass in against the bullet. If you try to put much more on it you run the risk of bulging the brass.

 

[Walkalong]

I like to see 1/2 of the cannelure out, so the case mouth is rolled into the deepest part of the cannelure.

 

[Frag]

Another one here that taper crimps plated bullets. Works very well. These are 38 specials in a GP100. No issues with setback at all. But there is minimal recoil, so i wouldnt expect there to be regardless of crimp type.

 

[moxie]

What is the purpose of the crimp? Twofold.

One, to prevent "bullet jump" in heavy loads. This is where the bullet overcomes case neck tension and backs out or "jumps" out of the case. This can lead to the bullet being caught between the cylinder and the frame. No fun.
Two, to help ensure adequate ignition of the powder by keeping the bullet in the case just a tiny bit longer. This usually applies (if really at all, IMO) to large cases using powder charges that fill only a small percentage of the available space, typically with black powder legacy calibers such as .45 Colt. Big fat cartridges in other words. The .38 Spl./.357 Mag. are not in this category.
So, in the first instance, is your bullet being held in place by good case neck tension? If so, then really no crimp or taper crimp is all that's required. Check case neck tension by pushing a completed round against the bench, hard, with two hands. It shouldn't move. Check for bullet jump by loading up a cylinder and measuring remaining rounds with a caliper after each shot. If no jump then no crimp is needed. If jump, then crimp. Measure again and determine if more crimp is needed.

The .38 Spl. rounds pictured in the first post have way more crimp than needed unless they are exceptionally hot loads intended to be fired out of featherweight revolvers like S&W Scandium types. That crimp should be more than adequate even for most .357 Mag. loads.

So, crimp when NEEDED and only enough to get the job done. Crimping when not needed just overworks the brass at the case mouth, shortening case life. Overcrimping can also deform the bullet, leading to inaccuracy.

Remember that proper case neck tension solves many problems, as noted above, and also bullet "setback" in autos.