44 Mag - how much crimp

[stoneke]

I have been reloading for my 5" 629 Classic and finding quite a variation in accuracy. Two loads are better than all the others (to include mild 200 and 240 gr Oregon Lazercast loads). The best is the 240 Speer jacketed SWC (.430") with 23 gr. H110 (mag pr) at 1307 to 1332 fps. This load has as heavy a crimp as I dare with a Lee crimp die. The second best is a 200 gr Nosler HP with 22.5 gr AA#9 at 1381 to 1445 fps. Five shots @ 25 yds measure 1 1/2" with a sixth shot flyer out another inch. I crimp this load as heavy as I can into the cannelure, but less of a crimp than the 240 load.
Question: Does the Nosler jacketed bullet with the cannelure, and those loads with faster burning powder require less of a crimp than a full house SWC bullet with a defined crimp shoulder? Any first hand experiences out there that could lend some direction?

 

[Drail]

Over crimping will not gain you anything and will cause case mouths to split from overworking and deform bullets (which will afeect accuracy). Are you asking about how much crimp in the interest of affecting accuracy or are you experiencing bullets pulling forward under recoil? A moderate crimp should be all you really need.

 

[cochise]

Stoneke,I found the length of the brass is very important to the crimp and to the pressure build up. I use RCBS roll crimp dies and they work fine for me. The pressure to crimp, on the lever, isn't all that much; so long as the adjustment of the die is correct. You need to "feel" the seating and crimping as you pull the lever. Basic reloading skill.

I do change the depth of the die in the press when I use lead vs jacketed. The crimping pressure remains the same. I've loaded Nosler, Hornady, Speer, Sierra, and ooddles of LSWC. They all work the same but die adjustment is necessary for each one.

I don't know if I quite explained my self enough. I hope I got the idea across.

 

[stoneke]

The Lee die claims that you can't overcrimp with their product. I find that you can first get a nice roll crimp and then adjusting farther, you will get a "crimped belt" on the top of the crimp. I guess that I need to try a little less crimp and see what the accuracy tells me.
Any further suggestions are most welcome.

 

[Bottom_Gun]

I agree with Cochise. The length of your brass will determine the consistency of your crimp, which affects your accuracy. I found sorting my brass by length and adjusting for it helped my accuracy. I normally crimp hot loads a bit more than target loads. Also heavier bullets, depending upon your load, will sometimes require a heavier crimp than lighter bullets due to the increased recoil.
I also discovered (the hard way) that some powders such as H110 require a somewhat heavy crimp to ignite reliably.
Experimentation is the key. Keep checking the unfired rounds in your cylinder to make sure your slugs aren't walking forward under recoil.

 

[Fishslayer]

The Lee die claims that you can't overcrimp with their product. I find that you can first get a nice roll crimp and then adjusting farther, you will get a "crimped belt" on the top of the crimp. I guess that I need to try a little less crimp and see what the accuracy tells me.
Any further suggestions are most welcome.

It's been explained to me (someone correct me if I'm wrong) that the "belt" is a sign of overcrimping.

I believe the Lee die you refer to is the LFCD AKA Lee Factory Crimp Die AKA Taper Crimp die. This is a taper crimp die and a completely different animal from the seating/crimp die, which puts in the roll crimp.

As has been mentioned, case length is the major factor in getting a good consistent roll crimp. I bought the Hornady trimmer & my .357 is much nicer now. I recommend a trimmer of some sort.

You should not need to use both roll & taper crimp. The LFCD has a sizing ring in it which will ensure that the round will go in the chamber.

The roll crimp serves two purposes. It helps slower powders build pressure for efficient burning and keeps the other bullets in the cylinder from moving forward under recoil. If this happens they can actually bind up your cylinder.

 

[dla]

You can squash things pretty tight with the FCD. Since you are using a Mag primer, I don't think you would have cold weather squib problems with that H110 load without the heavy crimp. 2400 and AA#9 are much faster powders and they don't benefit from a heavy crimp.

You might want to evaluate your present crimp by checking for bullet pull. Start with a full cylinder, fire one shot -> inspect the remaining 5, fire another shot -> inspect the remaining 4, and so on. I don't think you'll have a pull issue with the mountain gun but it doesn't hurt to check. In general, I've found bare lead to be more slippery than copper, and I've never experienced severe bullet pull with jacketed.

I like the FCD because I don't have to trim brass to the same length to get a consistent crimp. I load for a 329pd and I use a Dillon SDB for volume production. Often I will run the rounds through the FCD just to be sure.

 

[Fishslayer]

. 2400 and AA#9 are much faster powders and they don't benefit from a heavy crimp.
.

Every magnum load I've ever seen with 2400 recommends a stout roll crimp.

Not sure just how much faster 2400 is than H110 but it's only 8 slots faster on the Hodgdon's chart.
Burn Rate

 

[fredj338]

With uberslow powders, a good crimp & high load density give best results. It's one reason I have moved back to 2400 for my magnum handguns. It seems more uniform when not loading right at max. H110 & W296 seem to want to be max or nothing for most uniform results.

 

[dla]

Every magnum load I've ever seen with 2400 recommends a stout roll crimp.

Not sure just how much faster 2400 is than H110 but it's only 8 slots faster on the Hodgdon's chart.
Burn Rate

2400 is a lot faster than H110. You don't need a mag primer with 2400. I wonder if the "stout roll crimp" isn't more to prevent bullet pull, than to raise start pressure.

 

[Fishslayer]

2400 is a lot faster than H110. You don't need a mag primer with 2400. I wonder if the "stout roll crimp" isn't more to prevent bullet pull, than to raise start pressure.

That could be. I know that Alliant actually lists a recipe on their website for Blue Dot in a .45ACP which would tell me that a taper crimp is OK with slower powders. I've never tried it.

I've fired some overcrimped 2400 loads & I'll confess I'm not a good enough pistol shot to notice if there was any difference. Nothing blew up tho...

I'll go ahead & make up a few taper crimped .357s with 2400 & see what happens. The experts say I'll get chunks of unburned powder everywhere but ya never know.

 

[Rodentman]

I find that I need to trim my hot loaded brass (not very often) but it is necessary to do this to get the bullets seated to the proper depth for crimping in the cannelure. Also, the case length will affect the amount of the crimp. Brass needs to be virtually the same length unless you want to adjust the seating die as you go.

 

[buck460XVR]

As mentioned by others, with H110/W296 you need a firm, consistent crimp for consistent ignition to get the best accuracy. Since consistent crimps are dependent on consistent case length, I do this by either sorting brass by length or trimming brass.

 

[Shuz]

Folks, in my experience with the .44mag and cast boolits, I've found that case neck tension is far more important than any degree of crimping, When I first got my 329PD about 6 years ago, I was experiencing extreme boolit jump to the extent that the cylinder would get tied up after just 2 shots. I tried the Lee Factory crimp die and that did not help at all. I then contacted Dillon, and had them send me a smaller diameter expander plug for my Square Deal B. The boolit jumping problem disappeared.

 

[dla]

Folks, in my experience with the .44mag and cast boolits, I've found that case neck tension is far more important than any degree of crimping, When I first got my 329PD about 6 years ago, I was experiencing extreme boolit jump to the extent that the cylinder would get tied up after just 2 shots. I tried the Lee Factory crimp die and that did not help at all. I then contacted Dillon, and had them send me a smaller diameter expander plug for my Square Deal B. The boolit jumping problem disappeared.

You bring up a good point about neck tension - and I might just give Dillon a call about the expander. Do you know if it is standard item?

However I've never had a problem with the FCD crimping into the crimp groove - it holds and I too shoot a 329pd. But I much prefer to just "load and go" with my SDB and not have to fiddle so much with the roll crimp or run the finished rounds through the FCD for insurance.

 

[BruceM]

"I've found that case neck tension is far more important than any degree of crimping"

Yep!

It's a mistaken notion that the amount of crimp is the determining factor in uniform combustion of slow burning propellants and eliminating bullets "jumping the crimp". Neck tension due to a correctly sized expander is the controlling factor. Crimp is the last & worst line of defense relative to these problems.



Bruce

 

[Shuz]

You bring up a good point about neck tension - and I might just give Dillon a call about the expander. Do you know if it is standard item?

However I've never had a problem with the FCD crimping into the crimp groove - it holds and I too shoot a 329pd. But I much prefer to just "load and go" with my SDB and not have to fiddle so much with the roll crimp or run the finished rounds through the FCD for insurance.

dla--I don't know if they "catalog" different expander sizes, but all I did was ask for a smaller one than the one I had and they sent me a much smaller diameter. It's been quite a while now, but I think the one they sent me measured .003 less than the one I had been using.

I'm with you, the SDB is designed for "load and go" and I don't wanna have to mess around with a Factory Crimp Die in another press.

How's your 329PD top strap gas shield holding out?

 

[dla]

dla--I don't know if they "catalog" different expander sizes, but all I did was ask for a smaller one than the one I had and they sent me a much smaller diameter. It's been quite a while now, but I think the one they sent me measured .003 less than the one I had been using.

I'm with you, the SDB is designed for "load and go" and I don't wanna have to mess around with a Factory Crimp Die in another press.

How's your 329PD top strap gas shield holding out?

Since I switched to Ramshot Enforcer exclusively, the shield shows very little wear. The only powders that cut the shield are H110/W296 and LilGun. Enforcer is a little slower than AA#9 and 2400, so it gives higher velocities than those two. I lose a little velocity by not using H110/296 & LilGun, but that doesn't matter to me.

What I've learned is stay away from the abrasive powders and the 329pd cylinder, throat and shield hold up fine.

S&W329pd Information

 

[Rodentman]

I use a Lee universal flaring die for all my brass (except the .45 which is too short for use in this die.) I flare minimally for all calibers. I agree that crimp isn't gonna substitute for neck tension, witness the .357 sig.

 

[Nemo288]

Yep on the Lee expansion die (which I polished down .000a bit).
They seem to smaller than the rest which is good. A Very small
flare on the case, just enough to accept the bullet.
I use a Redding TiC sizing die, the Lee expansion die, Redding
seat die and the Redding's profile crimp. This is the best crimp die
I have ever used. Once set up for copper with cannelure it also
works for lead Keith type bullets. Recommended.
The taper crimp is only needed for lead bullets with no shelf
like some of the plated offerings.

If you can see a slight bulge where the bullet is lodged in the case
then you have good friction. If not you are over expanding the case
mouth.

Another trick to all this is to trim cases to exact length.
There is no way in hell you can achieve a consistant mouth
or crimp without length being exact.

I trim every 3 or 4 loadings.

Notice the bottom 2 cartridges and the slight swell at the bottom
of the bullet. This is what you want.

---
Nemo