Taper crimp vs Roll Crimp at target velocities which is best??

[10mmShooter]

Test parameters: Guns 8 3/8 Anaconda, 8 3/8 inch 686, 629 PC Hunter(8 3/38), and 629 PC Competitor(6 inch)
Brass Fed, RP, WW
Purpose of load is paper punching. Velocities 950-1150 fps range
Powder Alliant Green Dot and AA#5
Bullet: SWC in 255gr for .44 and 150g for .357
Chronographed using to two different Chronys


Gentlemen I just wanted to go over my experiences and see if you guys have had similar experiences. With taper vs roll crimping at target velocities, with AA#5 and Green Dot.

Back story recently I purchased a new Henry rifle in .44, which I had to buy a Saeco round nose mold for and since its a tube magazine I needed to roll crimp the bullets to prevent setback in the magazine. I used a moderate crimp for my target load of 6.8 grains of Green Dot, with Saeco 240gr round nose. This gave me a nice 1100 fps out of the rifle. SD was between 10-19 fps, and ES runs 30-40 fps.

So this got me thinking about taper vs roll crimp in my revolvers, because prior to purchasing the Henry all my .44/.357 caliber target loads were just taper crimped (my thoughts where to avoid over working the brass and shortening its life) also I always taper crimp just enough to remove the case mouth flare, and avoid any bullet deformation.

So my results using AA#5 7.5 grs in .357 brass, both moderately roll crimped vs taper crimped showed 1150 fps, and SD <20 and ES <40 fps

For all the .44 revolvers 6.8 grs of Green Dot roll crimped vs taper crimped showed 950 fps, SD <15 ES <30.

My conclusion is that using #5, and Green Dot at target velocities, 1150 fps for .357 and 950 fps for .44 . In my guns a good roll crimp vs a good taper crimp makes no difference in ES, or SD or velocity or on paper down range.

As with most things every ones experience my be different but at 25 yards for me, in my stated applications, roll crimping shows no benefits over taper crimping.(although it does work the brass more)

Also curious I have shot the stated loads for 20 years and never seen had any bullets break free and move out of the case under recoil with a taper crimp. This seems to be repeated over and over about revolver reloading, now granted my revolvers are large and heavy and loads are moderately light for calibers, and the gun weight absorbs lots of the recoil energy. Again with so many things I think each person applications are different.

Just a point of clarity, I'm referring to taper crimp vs roll crimp used in revolvers.....NOT the Henry rifle(crimp is the way to go due to the tube mag)

[prs]

If a bullet design is provided with a roll crimp groove and the cartridge design relies upon the case rim for head spacing, your choice is rather obvious. If you are using a tube type magazine, the above design is your most appropriate choice. If the bullet design has no roll crimp groove, I would expect best accuracy with a taper crimp due to less chance for deformation of the bullet in the crimping process and roll crimps in rounds that head space on case mouth seems to fly in the face of common sense; to me anyway. I think that your experiment supports the point of view where case stretch fit over the bullet is the prime factor for bullet retention (compared to type or degree of crimp) and thus helps with consistent ignition.

Now, the important stuff; where did ya get the Green Dot!?

prs

[1Shirt]

Trial and error, and go with what works best for you! No magic answer for this question in my opinion.!
1Shirt!

[10mmShooter]

Yes true PRS, I believe we are in agreement, that brass case sizing specifically in the neck area is critical to proper bullet retention, much more so than the crimp. My .308 M1a comes to mind, no crimp at all, but yet it holds the 168g match king bullet just fine even during the violent stripping from the mag and hitting the ramp into the chamber, with no issues.

ah my Green Dot, been working on my reserve of 13 pounds from 2010, only a few pounds left, but I picked up another 8lber at the gun show a few months back pricely at @$220 but at least I didn't have to pay Hazmat or tax or shipping. I grabbed a 8lber of Red Dot and #9 at the same time, so it was good day :)

[MtGun44]

Lots of possible variations that MIGHT happen, I agree with 1Shirt. I think the answer can
be different with different powders, primers, case neck tension, and many other significant
variables. Some powders may need a strong resistance at first, so case neck tension and
crimp might need to be tight, others light easily and there is no difference. Same with other
variables. I think this needs to be checked with each load, really.

Bill

[Digital Dan]

Some years ago I designed a paper patch bullet of 300 grains, a RFNFB. My purpose was for a 77/44. A short excursion into roll crimping provided the only leading over the course of 1000+ rounds. They are max loads w/ Li'l Gun.

A friend with a Redhawk wanted to try some and they shot quite well. So much so that during the time we were in contact he shot over 100 rds, all taper crimped. There was no dislocation of the bullet due to recoil. They were not kind to hogs.

[fecmech]

A couple years ago I tried the same load of 2400 and 358429 both with a heavy roll crimp and my usual taper crimp. Ballistics were identical with a 10 shot string on each. I have used a taper crimp on all my 38 spl and .357 loads for as long as I can remember. My standard .357 load is 15/296/358429 for about 1250fps and I don't get any bullet movement. It seems to work for me.

[prs]

Yes true PRS, I believe we are in agreement, that brass case sizing specifically in the neck area is critical to proper bullet retention, much more so than the crimp. My .308 M1a comes to mind, no crimp at all, but yet it holds the 168g match king bullet just fine even during the violent stripping from the mag and hitting the ramp into the chamber, with no issues.

ah my Green Dot, been working on my reserve of 13 pounds from 2010, only a few pounds left, but I picked up another 8lber at the gun show a few months back pricely at @$220 but at least I didn't have to pay Hazmat or tax or shipping. I grabbed a 8lber of Red Dot and #9 at the same time, so it was good day :)

WOW! Your powder stores recovered, but your bank account..... Oh well, we can't take it with use.

prs

[bobthenailer]

I use a taper crimp for revolver straight walled cases such as 38/357 , 44/44 mag, 45lc/454 casull for most loads in the 700 to 1,100 fps velocity range and a roll crimp for loads with higher velocity.
For most i have at two crimp dies a taper & a roll . for the 454 casull i have three a taper, med heavy roll crimp for cast and heavy roll crimp for jacketed bullets. i dont like to keep readjusting crimp dies as its hard to reduplicate the crimp exactly. i also trim my brass every so often after being sized first, so brass length is on min spec

[44man]

Once you have case tension things work. I have shot too many revolver loads, heavy by the way, with no crimp but it takes single shot loading. A roll crimp of just enough is needed with heavy loads because it helps prevent recoil pull. You can get away with mouse fart loads with a taper crimp. When you say it will hold 320 to 330 gr boolits in a .44 at over 1300 fps, we might go toe to toe.
I seen factory loaded cast loads with full profile crimps pull .454 boolits with two shots and lock up a Freedom and a SRH.
Yes, a roll crimp with dead soft boolits will not open a crimp so you size and scrape the boolit.
You must understand it is boolit passage that irons out the crimp, it does not "jump" open from pressure.