Experiment results--crimping factory ammo

G

Gene Pool

New member
Gentlemen,

I have learned that crimping reloaded handgun ammo generally results in better accuracy than ammo that is not crimped. The other day I experimented with some 45 ACP Winchester factory white box FMJ ammo. I took 10 rounds out of the box and, on 5 of them, I used my Lee factory crimp die adjusted for a "light" crimp. The other 5 I left as they came from the box. Next I loaded them into magazines and fired them off sand bags at 30 feet with the same pistol. Here you see the results--the target on the left is with the un-crimped rounds. The target on the right is the rounds with the slight crimp.

I am not sure what good this experiment did, or will do, or of what value it is, other than satisfying my curiosity.

Gene Pool
 

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Interesting about the accuracy.

Another member did the same with rifle ammo and while not achieving better accuracy, he did notice less extreme velocity spread.
 
I get about 10-15% better accuracy with lightly crimped rounds over non crimped. Proved it to myself a few years ago. This is with both handgun and rifle rounds. Therefore, I crimp my reloads. I takes what, 2 minutes extra to crimp 20 rounds?
 
What was the measurement of your 45 ACP crimp?

I also use a Lee FCD, and I set the die to apply a crimp of 0.470" on 45 ACP.

Bayou
 
I have Lee factory crimp dies, I do not use them but I have them just in case. I am the fan of bullet hold, I want all the bullet hold I can get. When it comes to experiments I suggest someone make an attempt to determine the difference in bullet release in time between a case with 40 pounds of bullet hold and 60 pounds of bullet hold and then measure the difference in pounds between a Lee factory crimp and a roll crimp and a tapper crimp.

All of that in time and distance. A good start would be to purchase R. Lee's book on modern reloading and then read it.

F. Guffey
 
<<What was the measurement of your 45 ACP crimp?>>

As per Lee's instruction sheet that come with the die, I ran the top down to where it contacted the case rim, then turned it another half turn for what Lee says is a light crimp. It's the same crimp I use when I load cast lead and plated bullets.

Gene
 
Gene,

You should repeat the experiment a couple of more times. 5-shot random group error is not insignificant, and getting the same result two more times (or shooting two 10 or 15-shot groups) will rid us of that specter. I don't really expect a different result (reasons below) but it's always nice to please the data gods.

I don't have the 45 Auto CFCD, but even if I did, I don't have your box of cartridges, so the amount of spring-back I got might differ. If you don't mind, do a before and after check across the case mouths of your lot of white box with the calipers and report what you get. 45 Auto SAAMI standard is 0.467-0.473" at the case mouth.

The reasons I think you will see the same thing are several. One is that the old time bull's eye target shooters used to roll crimp 45 Auto into lead bullets, leaving the shoulder of the H&G 68 type bullets sticking out far enough to get into the throat to center the bullet. They reported this produced the best accuracy. I know that spoils headspacing on the case mouth, but these loads, from the photos I've seen of them, would have headspaced either on the extractor or the bullet making contact with the barrel throat.

I try to do the latter thing just by seating out enough to headspace on the bullets. When I started doing it I measured about 40% decrease in group size and reduced leading with cast bullets. I never went to roll crimps because they make the case mouths split sooner. Also, as long as the gun was more accurate off bags than I could hold offhand, I didn't fret about it. For combat shooting it matters even less, as a gun that shoots 4" at 50 yards is as good as one that shoots 2" at fifty yards on those kinds of targets.

An item in one of the gun rags long ago was that folks shooting pistol at the National Matches reported military 45 Auto ammo to be consistently more accurate than its commercial counterparts. It was finally traced to the pitch seal in the military cases holding onto the bullet harder than the case alone did. The added start pressure then made the powder burn more consistently and the barrel time more consistent. In a pistol, how consistent the barrel time is affects vertical stringing. Consistent ignition time affects how much influence any shooter movement errors have. Higher start pressure brought about by higher bullet pull can affect both.
 
I have never heard of NOT crimping pistol rounds. Is not store ammo crimped?.
I ask because I have never bought store ammo before, but I assume all pistol ammo is crimped.
 
<<Is not store ammo crimped?...I assume all pistol ammo is crimped.>>

Apparently the white box Winchester 45 ACP is crimped enough to eliminate the "flair." I miced the loaded rounds and found the same dimension all the way to the mouth of the case. For best accuracy, I load plated 40 S&W that way for my Sig P229.

Gene
 
"Crimping kills accuracy in rifle ammo."

If so, how do you explain the consistent .50-.75" 100 yard groups I get with .223 ammo loaded with a crimp. Crimping bullets w/o a cannelure in random willy-nilly fashion MAY reduce the accuracy potential.

Regarding the OP: the ammo used may have been some older production and the FCD refreshed the case mouth tension making it more consistent.
 
Apparently the white box Winchester 45 ACP is crimped enough to eliminate the "flair." I miced the loaded rounds and found the same dimension all the way to the mouth of the case. For best accuracy, I load plated 40 S&W that way for my Sig P229.
Click to expand...

I built a Johnny Cash ACP45 1911 starting with a Remington Rand slide. It was accurate and liked new, factory over the counter ammo. And then; I started reloading for it. It did not like my reloads, a local reloader told me I did not know how to load for the 45 ACP.

I have at least 10 boxes of military surplus 45 ACP ammo; I measured a few of them and compared the surplus ammo measurements with factory/new Winchester ammo then compared the dimensions to my reloads. My build did not like ammo that had a case that liked like it swallowed a bullet; SO I DID AN EXPERIMENT! I used a RCBS carbide 45ACP full length sizing die to remove the bullet line from my cases. After reducing the diameter of the case by smoothing my cases out my reloads flew through the pistol like factory, new over the counter ammo.

And then I met the reloader at the range with 4 of his 45 ACPs and my 3; no luck, his ammo was not feed. I left the range and sized his loaded rounds with the carbide die, then returned.

My crimp dies will not remove the bullet line, the bullet line give the case the appearance of a snake that swallowed something.

F. Guffey
 
"Crimping kills accuracy in rifle ammo."
Click to expand...

I did not read through all of the responses but I said Lyman said crimping bottle neck cases could be a bad habit. Then there was the ‘ because’; because if the cases length is not the same the amount of crimp can not be the same. Then they said crimping can reduce bullet hold; they said bullet hold because neck tension had not been invented yet. They claimed the bullet is moving down when the bullet is being seated during the bullet seating operation; they suggested crimping while the bullet is being seated can cause the mouth of the case to dig into the bullet and force the neck to expand below the crimp and force the case neck down. They said the neck can expand below the crimp and under extreme conditions the shoulder/case body juncture can upset/bulge.

I am the fan of bullet hold; if I have a rifle that does not like bullet hold it does not get shot. Same for the running starts, I am the fan of the running start; I want my bullets to have that ‘jump’.

And then I visited Dillon in Arizona, they said I should seat on one position and crimp on another. Basically I said I did not need their 4 position press because I use a lock out die for straight wall cases; meaning I was not starting over on another set of dies. It was about that time they informed me they had a lot of reloaders using there press with non Dillon dies.

F. Guffey
 
Your results may be very true; however,
the subconscious is an amazing thing. If science, you have do a double-blind test. The person shooting can not know what variable each set represents. You mind is quite capable of achieving whatever results you "want," without you even being aware of it.
Consider the Ouija board for one obvious way your mind can trick you.
 
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