Crimping 38 special

[John Hill]

I am confused about how much to crimp my 38 special cases using 158 grain lead semi wad cutter bullets. The SAAMI charts of the specs do not address this question. Since I flare the cases just enough to start the bullet, do I use the crimping die to just close or "tighten the flared area till it just fits nicely in my revolver cylinder or do I want to actually roll it inward some? I wrinkled half a box of rounds by having the crimping die adjusted too low. Any advice is appreciated.
thanks
John

 

[bigmoose]

Just slightly roll the crimp so the case mouth slightly curls into the crimping groove of the bullet. This will prevent the unfired bullets from "walking" out of their case during recoil. It will jam up your revolver if the bullet protrudes out of the front of the cylinder. It also helps to achieve proper and uniform pressures from round to round.

I seat all the bullets first and then adjust the die (back off seating portion, bring down crimp portion of die) to only perform the crimp on the second pass. Time consuming, yes, but I only load around 2 boxes at a time. If adjusted properly, very little pressure on the press handle is required to roll the crimp. Hope this helps.

 

[LoboGunLeather]

Just slightly roll the crimp so the case mouth slightly curls into the crimping groove of the bullet. This will prevent the unfired bullets from "walking" out of their case during recoil. It will jam up your revolver if the bullet protrudes out of the front of the cylinder. It also helps to achieve proper and uniform pressures from round to round.

I seat the bullet first and then adjust the die (back off seating portion, bring down crimp portion of die) to only perform the crimp on the second pass. Time consuming, yes, but I only load around 2 boxes at a time. If adjusted properly, very little pressure on the press handle is required to roll the crimp. Hope this helps.

Bigmoose has it exactly right.

 

[Nevada Ed]

There are three types of "crimp" for the 38 case.

Some that shoot low target loads with minimal recoil just
take out the belling which gives a light snug fit to the lead bullet.

Medium loads use the above crimp where the case has a slight
inward roll into the bullets grove. This crimp also works great
on copper jacket bullets.

On high vel or +P lead bullet loads I lower the die 1/2 turn more
and do a crimp that can be easy to see, to work with the high recoil of these loads.

Yow will have to find where "Your die" works with these styles of crimp to get your
loads where you want them.

I also log the height of the die & screw for the bullet being used
and add it to my notes for future loadings.

Good loading.

 

[WILDPIG]

I use a nice medium crimp for reasons listed above. For high velocity, I step up to .357 mag.

WILDPIG

 

[SgtLumpy]

You can test the effectiveness of the crimp.

Measure the Cartridge OverAll Length (COAL) of each of six rounds. Mark them somehow (sharpie) or just remember where you load them in your cylinder.

Load your revolver with six rounds.

Fire ONE of the cartridges.

Open the cylinder and measure the COAL of the remaining five cartridges. If the COAL has changed, they're not crimped hard enough. If the COAL is the same as before firing, the crimp is sufficient (or maybe too hard).

Basically you're causing the recoil to try and move the unfired bullets within their cases. If they don't move, the crimp is keeping the bullet in place.

I use a Lee combination crimp+bullet seating die with plated 158gr 38s over midrange target loadings (not too hot, not too mild). The Lee die (not the factory crimp die) does a "modified taper crimp". Or maybe they call it a "modified roll crimp". It's a taper at it's lightest settings. As you crank down the crimp die it becomes a roll. In my settings it's about one wrench flat down from when it makes contact. Sometimes just a tad more. Visually inspecting the finished round, you cannot see any roll.

Just to experiment, I have cranked the crimp die down far enough to crumple the brass case wall. It's not a lot further, maybe another 2 wrench flats past where I consider it "enough".


Sgt Lumpy

 

[mikld]

Simple illustration of a roll crimp. Image at far right shows a roll crimp into a crimp groove. IMO, the center drawing is too much taper crimp, and the left is what I use for all my semi-auto ammo...

If in doubt about the amount of crimp, look at a factory crimped round (not to be confused with a Factory Crimp Die)

 

[tlay]

I use a Lee factory crimp die on almost all of my reloading. It is easy to use and a no brainer.

 

[John Hill]

Think that my problem was not having the bullet seated to where the rim could be roll crimped into the groove. Instead, I was crimping into the side of the lead bullet very, very close to the actual grove.

Now to really straighten me out, when seating the bullet, do you seat until the brass is level with the top of the groove and then crimp into the groove or do you seat to maybe where the top of the brass is level with the center of the groove and then crimp?

Another thing that I found was that my brass was of different lengths, all within the maximum length. To be able to set my die for all, I plan on trimming all brass to the same length. I was going for a constant OAL. Big mistake. Duh.
Thanks
John

 

[rwsmith]

top of the groove

Now to really straighten me out, when seating the bullet, do you seat until the brass is level with the top of the groove and then crimp into the groove

Yes, level with the top of the groove. When the crimp rolls in, it will be right in the groove.

"in the groove"

 

[NevadaBob]

To get a good visual, pull a factory made round and notice the crimp on their bullet.

 

[MikeyB]

The majority of my .38 Specials are for target practice so I go with a very light crimp.

 

[hotrod150]

.......
I seat all the bullets first and then adjust the die (back off seating portion, bring down crimp portion of die) to only perform the crimp on the second pass. Time consuming, yes, but I only load around 2 boxes at a time......

What he said. I load lead wadcutters and semi-wadcutters, and I like a pretty firm roll crimp.

 

[Nevada Ed]

As a note, now that I have a chrony I can tune my loads to "Near" a Fac Dup or "what ever"......
but for "Best Accuracy" I some times have to adjust the amount of crimp on the bullet to get it just right.

A light crimp or a heavy crimp can call for a different amount of powder to stay in the fps area that I am looking for. A lot also depends on the powder you are using.

One reason I am SO HAPPY when I finally find a good accurate load!!

Best of luck.

 

[Peter M. Eick]

If you are wrinkling things, get a redding profile crimper. It merges the best of taper and roll crimps into one setup. I use them on all my revolver rounds.

 

[fatman73]

For 38 I use a slight crimp. You need a lot less than you actually think. Even my 357's I don't use a heavy crimp.

 

[mickeyblueyes]

SO one above mentioned a crimp thats to heavy. What are the symptoms that you are crimping too hard? I don't mean crumbled brass. what other issues are apparent?

 

[rwsmith]

Light crimp

For medium revolvers with .38, just a light crimp is needed. Perhaps in a J frame or alloy revolver a little more crimp would be needed.

 

[rwsmith]

If you dig....

SO one above mentioned a crimp thats to heavy. What are the symptoms that you are crimping too hard? I don't mean crumbled brass. what other issues are apparent?

If you dig into the side of the bullet or change its shape, that is too much crimp.

 

[GCF]

For cast bullet "target" loads, I've had the best accuracy from minimum loads of fast powder - & a very light (0.002" - 0.003") crimp. Trimmed brass. Some .38spl match shooters, recommend a 0.000" crimp.

That said, I've found that some what heavier powder charges, seem to do better accuracy wise - w/ a slightly heavier crimp.

As long as the bullets are not un-seating from recoil (doubtful w/ target velocity loads), a good rule of thumb, is no more crimp then is required for best accuracy.

I like the idea of the Redding Profile die, used in a separate step.

I use Dillon .38 / .357 dies, & have 2 sets - each w/ it's own different crimp profile. Dillon tells me that the old style is close to what would be considered a classic "taper" crimp, where as the newer is closer to a "roll" crimp.