OAL changed after applying med/heavy roll crimp...

[45acpguy]

Not a noob to reloading by any means, however, this is a new problem I've recently encountered. I just started loading for my .357 mag, .44 mag, and S&W 500 mag. I chosen to use my single stage press, seeing as I don't shoot a whole hell of a lot of either of these calibers.

The issue I'm having is, when I put a semi-heavy roll crimp onto the magnum rounds, the OAL decreases quite a bit as well. Example. I set the OAL for my .44mag rounds to 1.620". After putting a semi-heavy roll crimp on the cartridge, the OAL changes to about 1.605" - 1.600". Will this difference in the OAL creat unsafe pressure?

I started at the lowest powder charge and worked my loads up to about 80% of the max charge. I've loaded about 100rds so far, bumping every 20rds up .2gr as I'm trying to get my "perfect target/plinking load". I'm using 240gr SWC and Hodgdons CFE Pistol.

Obviously, I'm gonna have to accomidate the seating depth for the additional depth the crimp die puts on the projectile. I just don't wanna the last 100 rounds to be a waste...

[pacrat]

Not a noob to reloading by any means, however, this is a new problem I've recently encountered. I just started loading for my .357 mag, .44 mag, and S&W 500 mag. I chosen to use my single stage press, seeing as I don't shoot a whole hell of a lot of either of these calibers.

The issue I'm having is, when I put a semi-heavy roll crimp onto the magnum rounds, the OAL decreases quite a bit as well. Example. I set the OAL for my .44mag rounds to 1.620". After putting a semi-heavy roll crimp on the cartridge, the OAL changes to about 1.605" - 1.600". Will this difference in the OAL creat unsafe pressure?

I started at the lowest powder charge and worked my loads up to about 80% of the max charge. I've loaded about 100rds so far, bumping every 20rds up .2gr as I'm trying to get my "perfect target/plinking load". I'm using 240gr SWC and Hodgdons CFE Pistol.

Obviously, I'm gonna have to accomidate the seating depth for the additional depth the crimp die puts on the projectile. I just don't wanna the last 100 rounds to be a waste...

.015-.020" oal on an 80% book load, should create no unsafe pressure levels in a revolver case that big. Choot em.

Second underlined statement. YES, OAL and crimp, in same die is a balancing act. Between die height, off the shell holder, and position of seating stem inside the die.

Try this shortcut........seat a few bullets in cases to the desired height, without any crimp.

Back off the stem, and then adj die height to make the crimp you desire. Lock die.

Then screw stem in until it firmly contacts seater to already crimped bullet. Lock stem.

Done. You now have the crimp you desire, and the stem is set to the OAL you desire.

JM2c

[45acpguy]

.015-.020" oal on an 80% book load, should create no unsafe pressure levels in a revolver case that big. Choot em.

Second underlined statement. YES, OAL and crimp, in same die is a balancing act. Between die height, off the shell holder, and position of seating stem inside the die.

Try this shortcut........seat a few bullets in cases to the desired height, without any crimp.

Back off the stem, and then adj die height to make the crimp you desire. Lock die.

Then screw stem in until it firmly contacts seater to already crimped bullet. Lock stem.

Done. You now have the crimp you desire, and the stem is set to the OAL you desire.

JM2c

On these .44 mag cartridges, I was actually using Lee carbide dies with the Lee factory crimp die. I haven't experienced the Lee factory crimp die ever altering my OAL. I also use Lee dies on my 550b pumping out 9mm and 45acp, however, I'm only applying a light/mild crimp.

[357magnum]

Crimping your cases should not change your OAL.
Sounds like something is not tight, seating plug or lock ring on the die itself.

[sofbak]

I use the Lee FCD on .40, .45acp, and .45colt but I only put a light crimp on all.

My oal grows by .002 to .004.

You must be putting a really deep crimp on those to shorten them by that much.

Pictures???

[Eljay]

I often see some small OAL changes after crimping. Always good to double check that and not just after the seating stage. I'm surprised it changed that much but I also agree they should be fine to shoot since you're still a ways from max.

[Win231]

My experience exactly; especially with the S&W 500. When I'm setting the crimp, I start adjusting it at the bottom of the cannelure, allowing for the heavy crimp to push the bullet a bit deeper.

[pacrat]

On these .44 mag cartridges, I was actually using Lee carbide dies with the Lee factory crimp die. I haven't experienced the Lee factory crimp die ever altering my OAL. I also use Lee dies on my 550b pumping out 9mm and 45acp, however, I'm only applying a light/mild crimp.

Wasn't aware you were using seperate seat/roll crimp dies.

My Bad

Disregard previous post.

[Bill Steele]

CFE Pistol is a relatively fast powder when applied to magnum calibers, not sure why you would even need anything more than a light crimp. (Not questioning the use of a faster powder, I favor less rude loads in these calibers myself)

I understand the logic of the "heavy crimp" when loading max effort in some of the big bore magnum calibers and slower powders that come with them (although I am a little fuzzy on how this practice might actually hold up under scientific examination), but for faster powders in those same calibers, less has to be more in the crimp department.

PS - most powders exhibit a pressure curve when it comes to load density. Reducing by 20% from max will usually result in more than a 20% reduction in chamber pressure. That is a really big reduction.

[fguffey]

Crimping: Many years ago it was decided applying a crimp while the ram is moving up will result in something getting shorter. The die des not have case body support. There is an entire generation that clams the firing pin striking the primer shortens the case from the shoulder to the case head .005"+ meaning when the case is run up to the top f its travel the case is forced into some kind of a cone I ask: Why wouldn't the case get shorter? And then there are all of the bottle neck cases with bulges at the case body shoulder juncture with only a hint of a crimp.

F. Guffey

[45acpguy]

CFE Pistol is a relatively fast powder when applied to magnum calibers, not sure why you would even need anything more than a light crimp. (Not questioning the use of a faster powder, I favor less rude loads in these calibers myself)

I understand the logic of the "heavy crimp" when loading max effort in some of the big bore magnum calibers and slower powders that come with them (although I am a little fuzzy on how this practice might actually hold up under scientific examination), but for faster powders in those same calibers, less has to be more in the crimp department.

PS - most powders exhibit a pressure curve when it comes to load density. Reducing by 20% from max will usually result in more than a 20% reduction in chamber pressure. That is a really big reduction.

I was told by others that shot the .44 and- especially the S&W 500 a lot, that firm crimps were necessary on these cartridges so the projectile wont start to back out do to the heavy recoil.

[Bill Steele]

I was told by others that shot the .44 and- especially the S&W 500 a lot, that firm crimps were necessary on these cartridges so the projectile wont start to back out do to the heavy recoil.

I think a light crimp will hold anything but a full house load in your 500 and CFE Pistol won't deliver that.

If you have one of those hammer style bullet puller, put a light crimp on a dummy round and see how much whacking it takes to dislodge the bullet. In any case, if they do walk out, they will just jam the action, not the end of the world at the range.

[45acpguy]

OAL changed after applying med/heavy roll crimp...

I think a light crimp will hold anything but a full house load in your 500 and CFE Pistol won't deliver that.



If you have one of those hammer style bullet puller, put a light crimp on a dummy round and see how much whacking it takes to dislodge the bullet. In any case, if they do walk out, they will just jam the action, not the end of the world at the range.

Copy that, good to know! I will lighten the crimp on my 44 mag loads. Should I lighten up on the factory crimp for the S&W 500 as well? That I load with H110, not CFE...

[Bill Steele]

Copy that, good to know! I will lighten the crimp on my 44 mag loads. Should I lighten up on the factory crimp for the S&W 500 as well? That I load with H110, not CFE...

A full house S&W 500 load of H110/W296, 4227 or Lil Gun is a hand full. A light roll crimp will likely still hold the bullet, but maybe only do a few cylinders worth first time out just in case.

PS - The thing most people miss with the "good firm crimp" advice is when you get to the point that the case mouth is pressing against the inside of the cannelure groove, further pressure starts springing the case and reduces neck tension (the interference fit between the bullet and case), thus reducing the overall bullet hold. Lots of old timers (I unfortunately fall into that chronological demographic) get that all wrong.

[45acpguy]

A full house S&W 500 load of H110/W296, 4227 or Lil Gun is a hand full. A light roll crimp will likely still hold the bullet, but maybe only do a few cylinders worth first time out just in case.



PS - The thing most people miss with the "good firm crimp" advice is when you get to the point that the case mouth is pressing against the inside of the cannelure groove, further pressure starts springing the case and reduces neck tension (the interference fit between the bullet and case), thus reducing the overall bullet hold. Lots of old timers (I unfortunately fall into that chronological demographic) get that all wrong.

Excellent advice sir- thank you.