Some readers may be familiar with the crimp creep test I recently conducted on the Ruger Super Redhawk Alaskan chambered for .454 Casull, in which it was discovered that the bullets in some ammunition may actually cause the gun to lock up. I was discussing this test with a friend of mine at Smith and Wesson, and he suggested a similar test be done on their scandium-framed 329PD, a .44 magnum intended for backup/carry purposes. (A review of the 329PD can be found here.) Being a glutton for high-recoil punishment, I agreed.
In brief, crimp creep occurs when a heavy load is fired from a relatively light gun. The recoil imparted to the weapon is great enough that the inertia of the other bullets in the cylinder causes them to advance out of the case slightly. This usually occurs only a few thousandths of an inch for a given firing, though I have seen bullets jump as much as .020″. Crimp creep can occur in any kind of firearm, but I personally have only observed it in revolvers.
The purpose of this test was to evaluate several brands of .44 cartridge for their susceptibility to crimp creep. Originally, I planned to measure the crimp creep by the same criteria as I had the Ruger (to fire control cartridges until the gun locked up because a bullet couldn’t clear the forcing cone). I soon realized, however, that this wouldn’t be a good test. The length of the cylinder in the 329PD would require too many firings to get a bullet to lock up the gun.
Instead, I chose to count the number of firings necessary to cause the Cartridge Over-All Length (COAL) to grow by .050″ over its original length. The figure of .050″ is a bit arbitrary (I pulled a cartridge apart to measures the air space between powder and bullet, and this was the figure I got), but seemed like a useful place to cease testing. As a creep amount of .050″ would still allow the cartridge to be fired, I could also measure, to some extent, the effect of crimp creep on velocity as well, something I couldn’t do in the Ruger test.
- From a pool of ammunition, designate a small number of test cartridges. Identify these cartridges by marking the cases with a felt pen or something similar.
- For each test cartridge, measure the initial Cartridge Over-All Length (COAL).
- Load the 329PD cylinder with the test cartridge and five other (control) cartridges.
- Close the cylinder so that the test cartridge would fire sixth if all six rounds were fired.
- Fire a single round, recording the velocity of that bullet.
- Open the cylinder and remove the test cartridge.
- Measure and record the test cartridge’s COAL, and reinsert the test cartridge.
- Repeat steps 4 through 7. Each time the cylinder is closed, the test cartridge was positioned as the final of the unfired cartridges.
- Remove the spent control cartridge cases, reload and repeat as necessary.
- When the test cartridge COAL exceeds its original length plus .050″, terminate the firing of the control cartridges. (Note: I continued to fire some test cartridges well past this threshold because I wanted to observe the effects of extreme creep on velocity.)
- Fire the test cartridge and record the velocity.
Equipment Used In the Testing
An Oehler Research chronograph was used to measure velocity of the ammunition. Oehler has a reputation for being the top of the line, and after working with it for several hours of testing, I can understand why. Their product is easy to install and use, and delivers accurate, reliable results.
A Starrett digital calipers with accuracy to .0005" was used in the cartridge measurements.
Finally, a pair of Past Shooting Gloves saved the author’s hands from a lot of abuse!
Buffalo Bore 255 grain
Corbon BCHP 260 grain
Corbon DPX 225 grain
Corbon JHP 165 grain
Corbon JHP 240 grain
Hornady 240 grain
Speer Gold Dot 270 grain
Winchester Partition Gold 250 grain
Winchester Platinum Tip 250 grain
Winchester Super-X 240 grain
Analysis and Final Thoughts
It is evident that, as a precursor to gun failure, crimp creep in the 329PD is pretty much a non-issue. Given the number of firings necessary, one would almost have to try to get a bullet to creep enough to collide with the forcing cone. This is in direct contrast to the results of the Ruger test, and speaks well of the 329PD’s suitability as a backup gun.
The effects on velocity, however, are another story. While the extent of the effect was not entirely predictable, it is clear that even minor amounts of creep had a measurable effect on bullet velocity. In some of the test results, you can read across the tables (each row represents a separate cylinder of ammunition) and see the velocity numbers decrease from left to right. (As a side note, I would add that this is the only gun I’ve ever fired where I could actually feel the recoil increase as the cylinder became progressively empty.
Now: how serious a problem is this drop in velocity? That is a question you’ll have to answer for yourself. While slower-moving bullets will certainly drop faster, it’s doubtful that this will be much of an issue in a gun that’s intended to be used for extremely close encounters with extremely large enemies (spelled B-E-A-R-S). A greater concern, however, could be the effect of the reduced velocity on the bullet’s expansion properties. Discussions with some of the ammunition makers suggests that their bullets need to be around 1100 fps to reliably expand, and as the data show, bullets that crept often were considerably slower than this threshold. It was beyond the scope of this test to study terminal performance such as bullet penetration and expansion; perhaps we can address that in another test someday.
I think the bottom line is that you’ll want to acquaint yourself thoroughly with whatever ammunition you choose. Invest in several boxes at the range, and observe the results for yourself. The Buffalo Bore ammunition was the clear winner in this test, but is not necessarily the only ammunition that can safely be used. And, as was the case with the .454 ammunition for the Ruger:
Many readers will notice missing chronograph readings in some of the test reports. This was due to various reasons. Sometimes I wanted to finish a test despite fading sunlight; in these cases, the chronograph understandably became erratic. Also, toward the end of my testing, the beating that the 329PD was taking finally caused the rear sight to fly apart after a firing. Barrel-sighting this gun wasn’t too successful, to say the least. The failure of the rear sight also highlights the importance of frequent inspections for this gun…it is subject to high stress, and you don’t want it to fail when you most need it.
Finally, the author would like to convey his gratitude to Smith & Wesson and the ammunition makers for making this test possible.
If you have any questions or comments, or would like to submit another brand of ammunition for testing, please feel free to contact the author at the author’s email. I welcome your input.