Years ago I was reloading .38Spl. I was still working and really didn't have a good/dedicated area for the hobby and ended up selling my setup to a guy a work. I'm now retired and thinking about starting up again. I know it's a bad time (finding primers and bullets) but still thinking about it. I was using a RCBS Rockchucker with their carbide dies but can't remember if I was using a roll or taper crimp. I have found the RCBS carbide dies on line and they use a roll crimp. Is roll crimp what I want for .38 Spl and .357 Mag? Thanks!

The usual crimp die furnished with a .38/.357 die set is a roll crimp. You can buy taper crimp dies also. I use only roll crimp dies in this caliber but vary the crimp for HBWC (minimum crimp) vs .357 158gr SP (crimp almost to bottom of groove), for example.

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Science plus Art

If your bullets have a crimp groove use a roll crimp.

If these are wadcutters that will be used with a S&W model 52 then you may need to use a taper crimp ahead of the crimp groove in order to get them to feed through the magazine.

Ideally, it would be best to try both and shoot some benchrested 25 yard groups. I've seen slightly better overall accuracy with taper crimp in .38 Special, but I'm not sure the difference would be enough reason to buy another crimp die if you don't already have one. I can't recall using anything but roll crimp in .357, but a taper crimp might be fine.

I like a taper crimp for automatic pistols, but a roll crimp for revolvers. Especially magnum loads.

Generally speaking it is like DIYJ98 says.

Roll for 38/357

The 38 special and 357 Magnum dies came out with a roll crimp as standard equipment, that would work with the lead bullets and also the copper jacket bullets that had a good cannelure on them.

With todays plated bullets the "Can" is minimal or not even on the bullet........
so a taper crimp is best for this style of bullet.

You can set a roll crimp to where it just takes out the belling of the case for
auto pistols or plated bullets.
You only need to crimp medium to heavy loads in your revolvers, if there is a chance of bullet "Pull".

Suggest a roll crimp die and crimp in the crimp groove. I use both a Redding Profile Crimp Die or Lee Factory Crimp Die.

My rule of thumb; "Roll crimp for revolvers, and Taper crimp for Semi-auto's". The 38's I loaded for my 52-2 were Taper crimped. All 9mm, .380, .45acp, 10mm, etc are Taper crimped.

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H Richard
SWCA1967 SWHF244

I shoot blue bullets in 38 which are round nose smooth and no cannelure. Therefor they get a taper crimp applied with a 9mm die, just enough to bring in the case mouth, nice and easy does it.

I roll crimp, even if the bullet doesn't have a cannelure like some of the plated bullets I have. The die can still do it since the bullet is basically soft lead.

The reason for boh type crimps! A roll crimp is to prevent "bullet pull" on a revolver that would have a med to large recoil. Simple physics; for every action there is an equal, and opposite, reaction(bullet moves forward with a given force, the gun moves backwards with the same amount of force)!
In an auto a taper crimp is used because in most autos the round is headspaced on the case length! Bullet pull is not a factor because the next round is in the mag and can not move out of the case. All that being stated, I roll crimp all my 9mm, 38Super, 40S&W, 45 ACP, 10mm! They are all shot out of revolvers! !
jcelect

Unless for special applications, roll, profile or collet crimp for revolver handloads. Taper "crimp", aka "deflaring" die for semi-auto handloads. Many still shoot/reload for S&W Model 52 pistols and need a taper crimp. Plated bullets are recommended to use taper crimp (I will not/do not use plated for any revolver use, semi-auto handloads on rare occasions and only for experimenting or if I have no jacketed or run out of lead alloy).

And just like almost every other method of reloading, there are "exceptions" and personal preferences. I have loaded a lot of 38 Special wadcutters both HBWC and DEWC and lightly roll crimped, but many prefer a taper crimp. Worked quite well for me but I did not compete in Bullseye Shooting and my handloads were more accurate than I could shoot...