How much do you crimp your handgun loads?

Prof Young · May 27, 2025, 10:01 AM

Loaders:

My lee handgun caliber dies include a crimp die, and I usually do a "light" crimp. That means I screw the crimp die adjusting knob in one half turn after it has contacted the case mouth. A full turn of the knob makes a "heavy" crimp. I'm sure ballistically it makes a difference in terms of pressure, but what kind of difference and how much? I'm thinking I need to try some heavy crimping to see if it makes much difference in accuracy? (Yeah, I know there are many factors to accuracy.)

Talk to me.

Life is good.
Prof Young

**Unclenick** · May 27, 2025, 10:45 AM

Heavy crimps are often necessary in light revolvers to prevent recoil from "pantsing" the bullet out of the case, leaving the bullet sticking out too far and jamming cylinder rotation. Self-loaders don't do that. Instead, they bump the bullet noses with the magazine, so they are more prone to push a bullet in deeper if it isn't gripped firmly enough.

The drawback to heavy crimping is that it distorts the bullet. Does that matter? It depends on the cartridge and bullet. I've seen M2 Ball rifle ammunition that was heavily distorted by its factory crimp, but that would still hit within about a foot and a half at 600 yards. That's equivalent to under an inch and a quarter at 50 yards if you allow that MOA is determined by slow lateral drift, which is proportional to time of flight. So, will you notice that kind of error in a handgun? It depends on the handgun and load. Also, the shorter bullet may have a harder time with crimp distortion. You'll have to test for that.

The other thing a crimp does is increase the pressure at which the case releases the bullet. The late Richard Lee claimed that increasing this improves accuracy. I've seen reports of it going both ways (this would be with rifles, again), with the negatives especially at longer ranges. There may also be an optimal value for each load, or that advantage may be erased if a load is highly consistently assembled.

So, you're in for some experimenting.

totaldla · May 27, 2025, 11:42 AM

Johnny's reloading bench, a YT channel, did a test on 223, 55gr, using a lee FC die to vary the crimp from light to heavy, and then shoot groups. No difference at 100yds. Fun to watch.

I'm not good enough to know if my handgun crimping affects accuracy, but I do know that if I don't crimp enough I can get bullet pull with my 329pd and tie up the revolver. But I don't think this is as much of an issue with steel revolvers.

I did tend to overdo the taper crimp with 9mm - worried about bullet setback. In hindsight it was silly as the Dillon resizing die makes an obvious coke bottle shape for the finished round and I doubt setback would happen. Again, I'm not good enough to know if accuracy was affected.

Sorry for my rambling. When I started reloading 45acp many years ago, folks advocated a heavy taper crimp to improve 1911 feeding. I guess I went forward from there erring towards too much versus too little crimp. Since 99% if my handgun shooting was 25yds or less, I never knew whether or not I was ruining accuracy.

Have fun!

**44 AMP** · May 27, 2025, 01:26 PM

Light, moderate, firm, heavy, etc are all relative terms. Taper and roll crimps are different.

How much crimp is needed depends on the load you are shooting and the gun they are being shot from.

Crimp is applied to assist case neck tension in keeping the bullet from moving before you want it to. How much and what type varies with the individual situation.

Quote:

I'm sure ballistically it makes a difference in terms of pressure, but what kind of difference and how much?

There is no "one size fits all" answer. How much change and what the effects are is dependent on the combination of all the factors involved, the load, AND the gun used. With handguns, especially.

Mike38 · May 27, 2025, 10:01 PM

Prof Young, I also use the Lee crimp dies. I use what would be considered a "medium" crimp for all handgun cartridges, with the exception of .45acp where I use "light" which leaves the case mouth at an OD of around .469 - .470 which is how I was taught to crimp .45acp by many Bullseye shooters.

**Unclenick** · May 27, 2025, 10:30 PM

The effect will vary not only with the cartridge but with the powder burning characteristics. The faster pressure peaks, the higher the peak will be and the more velocity you will get. So, firing enough rounds, if you are having the effect of raising start pressure, you should see the mean velocity increase, but I wouldn't expect it to be by a lot. Instead, look for minimum SD as an indicator of improved consistency. If SD gets worse, you are likely making precision worse.

Recycled bullet · May 27, 2025, 10:48 PM

"I like to seat and crimp in two separate steps.

1) seat the bullet over the powder charge into the expanded case

2) back out the seating stem, and with the ram all the way up into the die, manually tighten- turn the crimp portion of the die with your fingers until there is a hard stop bottoming out against the case mouth. Slightly lower the ram to allow free clearance then tighten the crimp die an additional 1/8 or 1/4 turn. Test this setting on a seated cartridge. Test the completed ammunition in the intended firearm and verify function. Make sure that it fits the magazine. Make sure that it makes the trip from magazine to chamber with no stumbles. Make sure that it freely passes the plunk test, it needs to be able to fall into and out of the chamber without resistance. This adjustment works for me in my equipment for everything from 9x19 to 308 (this works especially well for the soft cast lead pointy plinker bullets in 308 Winchester), H&G 50 wadcutters and 38 Special and 358-429 and 357 Magnum brass. Back it off slightly if it's disturbing the bullet. Add a one additional 1/8 turn if the crimp is not satisfactory deep enough in the groove of the bullet."

**44 AMP** · May 28, 2025, 10:41 PM

My system is a little different. There are a few cartridges I load and use a separate crimp die (taper crimp), for all others I use the crimp in the seater die, and adjust to seat and crimp in one step.

Requires pretty uniform brass length, but once set up properly, it works like a charm, for handgun and rifle rounds that require a crimp.

nuchie11 · May 29, 2025, 05:16 AM

Crimping definitely plays a role, but how much it matters really depends on your bullet type, powder burn rate, and whether you’re shooting revolver or semi-auto.

A light taper crimp is generally enough for jacketed bullets in semi-autos. For revolvers, especially with slower-burning powders, a firm roll crimp helps maintain consistent pressure and prevents bullet creep under recoil.

Nathan · May 29, 2025, 05:51 AM

With autos, tight enough I can load them 5 times with under 0.002” movement.

With revolvers, tight enough I can shoot a full cylinder without movement.

Shadow9mm · May 30, 2025, 09:23 AM

Auto loaders, just enough taper crimp to remove the flare. Revolvers with a crimp groove in the bullet, heavy roll crimp.

**44 AMP** · May 30, 2025, 03:44 PM

How much of what depends on the bullet and the gun.

I have done some testing over the years, and I also load for some uncommon rounds, as well. The .44AMP uses a taper crimp, but it definitely needs a firm one, "just enough to remove the flare" doesn't cut it, for that round. With 9mm and .45acp, I give them a light "kiss" with a taper crimp die. They just feed better that way.

I've tested "standard".38s (158gr nominal 850fps 4") from N, K, and J frame S&Ws. UNCRIMPED fired from the heavy gun showed no bullet jump. From the K frame, sometimes bullets moved. Same ammo from the J frame and they moved alot.

The mass of the bullet and the weight of the gun and the amount of recoil play a part. Even in heavy guns, 44/45 slugs should be at least lightly crimped and heavy crimps are needed for heavy loads. Lighter .38cal slugs less so, but a good crimp is needed in anything more than light loads in a heavy revolver.

AL45 · June 13, 2025, 08:54 PM

Using the Lee crimp die, I do half turn on .380 and .45 acp. On .45 colt standard and Ruger only loads, I do a full turn. I use a redding crimp die for .454 casull, crimp extremely heavy and still struggle with bullet jump locking the cylinder down after two shots.

Ricklin · Yesterday, 12:28 PM

Quote:

Originally Posted by 44 AMP

How much of what depends on the bullet and the gun.

I have done some testing over the years, and I also load for some uncommon rounds, as well. The .44AMP uses a taper crimp, but it definitely needs a firm one, "just enough to remove the flare" doesn't cut it, for that round. With 9mm and .45acp, I give them a light "kiss" with a taper crimp die. They just feed better that way.

I've tested "standard".38s (158gr nominal 850fps 4") from N, K, and J frame S&Ws. UNCRIMPED fired from the heavy gun showed no bullet jump. From the K frame, sometimes bullets moved. Same ammo from the J frame and they moved alot.

The mass of the bullet and the weight of the gun and the amount of recoil play a part. Even in heavy guns, 44/45 slugs should be at least lightly crimped and heavy crimps are needed for heavy loads. Lighter .38cal slugs less so, but a good crimp is needed in anything more than light loads in a heavy revolver.

Thanks for that, the physics of the lighter gun is interesting. It's logical that the heavier projectile and the lighter gun would produce bullet movement requiring a healthy crimp. Thanks for proving that.

Recycled bullet · Yesterday, 12:46 PM

The light guns do function as a bullet puller. This is especially noticeable shooting Magnum loads through a J frame snubby.

Neck tension determines bullet pull. Crimp to help with feeding and provide marginal assistance with bullet pull.

Also crimped ammunition just looks so good.

Resistance to Bullet pull is set in the resizing die.

If you overdo the crimp it may distort the bullet and make it undersized and then no matter how far you roll or taper the brass into the bullet ogive or crimp Groove it can be still be moved with hand pressure due to an undersized section of the bullet.

If done right Crimping can also be a forming operation that will help generate consistency between the individual pieces of ammunition. I think It can help with ignition. I see this on target with 357 Magnum loads providing what I think is excellent accuracy.

I have noticed that my 358-429 hollow point bullets have a very wide and deep crimp Groove. This makes up for inconsistency with case length they all end up consistently crimped into the groove without having to trim a thousand pieces of 357 Magnum brass

.

Evaluate all of your processes that you use to handload your ammunition. A goal may be that the sum total will be of greater value than the component parts. AKA excellent ammunition!

jetinteriorguy · Today, 08:58 AM

In my magnum’s I use the Lee Collet Crimp die. You can apply a good heavy crimp as needed with no danger of over crimping and buckling the case. Plus it’s less dependent on absolute case length and in my experience easier on the case mouth. As far as semi auto’s I just crimp until I can’t get the bullet to move after pushing it into my bench top as hard as I can. This generally doesn’t require a very heavy crimp.

May 27, 2025, 10:01 AM	#1
Prof Young Senior Member Join Date: August 22, 2007 Location: Illinois - down state Posts: 2,508	How much do you crimp your handgun loads? Loaders: My lee handgun caliber dies include a crimp die, and I usually do a "light" crimp. That means I screw the crimp die adjusting knob in one half turn after it has contacted the case mouth. A full turn of the knob makes a "heavy" crimp. I'm sure ballistically it makes a difference in terms of pressure, but what kind of difference and how much? I'm thinking I need to try some heavy crimping to see if it makes much difference in accuracy? (Yeah, I know there are many factors to accuracy.) Talk to me. Life is good. Prof Young

May 27, 2025, 10:45 AM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,722	Heavy crimps are often necessary in light revolvers to prevent recoil from "pantsing" the bullet out of the case, leaving the bullet sticking out too far and jamming cylinder rotation. Self-loaders don't do that. Instead, they bump the bullet noses with the magazine, so they are more prone to push a bullet in deeper if it isn't gripped firmly enough. The drawback to heavy crimping is that it distorts the bullet. Does that matter? It depends on the cartridge and bullet. I've seen M2 Ball rifle ammunition that was heavily distorted by its factory crimp, but that would still hit within about a foot and a half at 600 yards. That's equivalent to under an inch and a quarter at 50 yards if you allow that MOA is determined by slow lateral drift, which is proportional to time of flight. So, will you notice that kind of error in a handgun? It depends on the handgun and load. Also, the shorter bullet may have a harder time with crimp distortion. You'll have to test for that. The other thing a crimp does is increase the pressure at which the case releases the bullet. The late Richard Lee claimed that increasing this improves accuracy. I've seen reports of it going both ways (this would be with rifles, again), with the negatives especially at longer ranges. There may also be an optimal value for each load, or that advantage may be erased if a load is highly consistently assembled. So, you're in for some experimenting. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

May 27, 2025, 10:30 PM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,722	The effect will vary not only with the cartridge but with the powder burning characteristics. The faster pressure peaks, the higher the peak will be and the more velocity you will get. So, firing enough rounds, if you are having the effect of raising start pressure, you should see the mean velocity increase, but I wouldn't expect it to be by a lot. Instead, look for minimum SD as an indicator of improved consistency. If SD gets worse, you are likely making precision worse. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

May 28, 2025, 10:41 PM	#8
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 30,435	My system is a little different. There are a few cartridges I load and use a separate crimp die (taper crimp), for all others I use the crimp in the seater die, and adjust to seat and crimp in one step. Requires pretty uniform brass length, but once set up properly, it works like a charm, for handgun and rifle rounds that require a crimp. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

May 30, 2025, 09:23 AM	#11
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 4,591	Auto loaders, just enough taper crimp to remove the flare. Revolvers with a crimp groove in the bullet, heavy roll crimp. __________________ I don't believe in "range fodder" that is why I reload.

May 27, 2025, 11:42 AM	#3
totaldla Senior Member Join Date: August 11, 2009 Location: SW Idaho Posts: 1,496	Johnny's reloading bench, a YT channel, did a test on 223, 55gr, using a lee FC die to vary the crimp from light to heavy, and then shoot groups. No difference at 100yds. Fun to watch. I'm not good enough to know if my handgun crimping affects accuracy, but I do know that if I don't crimp enough I can get bullet pull with my 329pd and tie up the revolver. But I don't think this is as much of an issue with steel revolvers. I did tend to overdo the taper crimp with 9mm - worried about bullet setback. In hindsight it was silly as the Dillon resizing die makes an obvious coke bottle shape for the finished round and I doubt setback would happen. Again, I'm not good enough to know if accuracy was affected. Sorry for my rambling. When I started reloading 45acp many years ago, folks advocated a heavy taper crimp to improve 1911 feeding. I guess I went forward from there erring towards too much versus too little crimp. Since 99% if my handgun shooting was 25yds or less, I never knew whether or not I was ruining accuracy. Have fun!

May 27, 2025, 10:01 PM	#5
Mike38 Senior Member Join Date: December 28, 2009 Location: North Central Illinois Posts: 2,757	Prof Young, I also use the Lee crimp dies. I use what would be considered a "medium" crimp for all handgun cartridges, with the exception of .45acp where I use "light" which leaves the case mouth at an OD of around .469 - .470 which is how I was taught to crimp .45acp by many Bullseye shooters.

May 27, 2025, 10:48 PM	#7
Recycled bullet Senior Member Join Date: November 13, 2022 Posts: 488	"I like to seat and crimp in two separate steps. 1) seat the bullet over the powder charge into the expanded case 2) back out the seating stem, and with the ram all the way up into the die, manually tighten- turn the crimp portion of the die with your fingers until there is a hard stop bottoming out against the case mouth. Slightly lower the ram to allow free clearance then tighten the crimp die an additional 1/8 or 1/4 turn. Test this setting on a seated cartridge. Test the completed ammunition in the intended firearm and verify function. Make sure that it fits the magazine. Make sure that it makes the trip from magazine to chamber with no stumbles. Make sure that it freely passes the plunk test, it needs to be able to fall into and out of the chamber without resistance. This adjustment works for me in my equipment for everything from 9x19 to 308 (this works especially well for the soft cast lead pointy plinker bullets in 308 Winchester), H&G 50 wadcutters and 38 Special and 358-429 and 357 Magnum brass. Back it off slightly if it's disturbing the bullet. Add a one additional 1/8 turn if the crimp is not satisfactory deep enough in the groove of the bullet."

May 29, 2025, 05:16 AM	#9
nuchie11 Member Join Date: July 18, 2019 Posts: 17	Crimping definitely plays a role, but how much it matters really depends on your bullet type, powder burn rate, and whether you’re shooting revolver or semi-auto. A light taper crimp is generally enough for jacketed bullets in semi-autos. For revolvers, especially with slower-burning powders, a firm roll crimp helps maintain consistent pressure and prevents bullet creep under recoil.

May 29, 2025, 05:51 AM	#10
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,807	With autos, tight enough I can load them 5 times with under 0.002” movement. With revolvers, tight enough I can shoot a full cylinder without movement.

May 30, 2025, 03:44 PM	#12
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 30,435	How much of what depends on the bullet and the gun. I have done some testing over the years, and I also load for some uncommon rounds, as well. The .44AMP uses a taper crimp, but it definitely needs a firm one, "just enough to remove the flare" doesn't cut it, for that round. With 9mm and .45acp, I give them a light "kiss" with a taper crimp die. They just feed better that way. I've tested "standard".38s (158gr nominal 850fps 4") from N, K, and J frame S&Ws. UNCRIMPED fired from the heavy gun showed no bullet jump. From the K frame, sometimes bullets moved. Same ammo from the J frame and they moved alot. The mass of the bullet and the weight of the gun and the amount of recoil play a part. Even in heavy guns, 44/45 slugs should be at least lightly crimped and heavy crimps are needed for heavy loads. Lighter .38cal slugs less so, but a good crimp is needed in anything more than light loads in a heavy revolver. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

June 13, 2025, 08:54 PM	#13
AL45 Senior Member Join Date: December 12, 2012 Posts: 778	Using the Lee crimp die, I do half turn on .380 and .45 acp. On .45 colt standard and Ruger only loads, I do a full turn. I use a redding crimp die for .454 casull, crimp extremely heavy and still struggle with bullet jump locking the cylinder down after two shots.

Yesterday, 12:46 PM	#15
Recycled bullet Senior Member Join Date: November 13, 2022 Posts: 488	The light guns do function as a bullet puller. This is especially noticeable shooting Magnum loads through a J frame snubby. Neck tension determines bullet pull. Crimp to help with feeding and provide marginal assistance with bullet pull. Also crimped ammunition just looks so good. Resistance to Bullet pull is set in the resizing die. If you overdo the crimp it may distort the bullet and make it undersized and then no matter how far you roll or taper the brass into the bullet ogive or crimp Groove it can be still be moved with hand pressure due to an undersized section of the bullet. If done right Crimping can also be a forming operation that will help generate consistency between the individual pieces of ammunition. I think It can help with ignition. I see this on target with 357 Magnum loads providing what I think is excellent accuracy. I have noticed that my 358-429 hollow point bullets have a very wide and deep crimp Groove. This makes up for inconsistency with case length they all end up consistently crimped into the groove without having to trim a thousand pieces of 357 Magnum brass. Evaluate all of your processes that you use to handload your ammunition. A goal may be that the sum total will be of greater value than the component parts. AKA excellent ammunition!

Today, 08:58 AM	#16
jetinteriorguy Senior Member Join Date: April 28, 2013 Posts: 3,465	In my magnum’s I use the Lee Collet Crimp die. You can apply a good heavy crimp as needed with no danger of over crimping and buckling the case. Plus it’s less dependent on absolute case length and in my experience easier on the case mouth. As far as semi auto’s I just crimp until I can’t get the bullet to move after pushing it into my bench top as hard as I can. This generally doesn’t require a very heavy crimp.