what is the best type of crimp for rifle loads ? or is it even worth it to crimp , does it help any thing at all ?
best type of crimp for rifle loads
- Thread starter savagehunter44
- Start date
Re: best type of crimp for rifle loads
I even skip that. Controlling neck tension makes crimping unnecessary and avoids the negatives that crimping can cause.
I even skip that. Controlling neck tension makes crimping unnecessary and avoids the negatives that crimping can cause.
Re: best type of crimp for rifle loads
I would go one step further than 427Cobra's comment that a crimp is not required, I would say that a crimp on bolt action rifle ammo is detrimental to optimum accuracy and should not be done. It introduces an additional variable to the mix. Variables are what we take extreme measures to eliminate in our efforts to produce top-notch accurate match grade ammo to shoot in our expensive rifles.
You Lee Factory Collet Crimp afficionados don't start building your letter bombs to send to me just yet. For evidence I would submit that there is no one in any type of competition from F class to benchrest or any other precision shooting sport and is winning, entertains the thought of crimping their match ammo.
However, crimping IS a vital requirement for ammo to be loaded in tubular magazines, heavy recoiling revolver loads, double rifles,military and law enforcement weapons and anywhere else that functional reliability trumps the accuracy requirement.
Paul
I would go one step further than 427Cobra's comment that a crimp is not required, I would say that a crimp on bolt action rifle ammo is detrimental to optimum accuracy and should not be done. It introduces an additional variable to the mix. Variables are what we take extreme measures to eliminate in our efforts to produce top-notch accurate match grade ammo to shoot in our expensive rifles.
You Lee Factory Collet Crimp afficionados don't start building your letter bombs to send to me just yet. For evidence I would submit that there is no one in any type of competition from F class to benchrest or any other precision shooting sport and is winning, entertains the thought of crimping their match ammo.
However, crimping IS a vital requirement for ammo to be loaded in tubular magazines, heavy recoiling revolver loads, double rifles,military and law enforcement weapons and anywhere else that functional reliability trumps the accuracy requirement.
Paul
Re: best type of crimp for rifle loads
for macth ammo, neck tension is all you need, for any conditions combat, cannelured bullet with roll crimp.
you pick.
cheers.
for macth ammo, neck tension is all you need, for any conditions combat, cannelured bullet with roll crimp.
you pick.
cheers.
Re: best type of crimp for rifle loads
I have crimped using a lee collet type die for about ten years. I have heard many claims that crimping kills accuracy. Many of the claims have to do with jacket deformation. On the flip side of the argument is the claim that crimping contributes to more consistent ignition and thus betters accuracy.
I can say definitely, I have no idea…………
A few years ago I took an identical .308 load and crimped 50 and left the other 50 alone. I couldn’t tell a lick of difference between them.
Still curious, I did a similar thing with a 22-250 load, only I did 25 of each. The crimped load shot slightly better by about 3/8”, more interesting is the crimped load had a 20 fps less spread over a chronograph.
I worked up a 7mm Mag hunting load for a buddy. We cut better then ¾” off his load with just crimping.
When I started on a 223/5.56 load (Auto) I always crimped. It made sense on an autoloader. An old fella at the range suggested I try not crimping as they usually shot better. I tried both crimped and not with bullets from 50, 55, 60, 68 and 75. I will honestly admit there were a lot of variables including crimping and I couldn’t tell any difference.
Lastly, I got to thinking maybe the crimped loads have more run out induced by the operation. Took 5, measured them, crimped them and couldn’t see any difference.
I have never been able to duplicate crimping causing accuracy problems in my work. I also don’t crimp the living daylights out of my loads. Now, when I first started loading I had all sorts of problems with a roll crimp, which is very sensitive to case length, that was a negative.
I have crimped using a lee collet type die for about ten years. I have heard many claims that crimping kills accuracy. Many of the claims have to do with jacket deformation. On the flip side of the argument is the claim that crimping contributes to more consistent ignition and thus betters accuracy.
I can say definitely, I have no idea…………
A few years ago I took an identical .308 load and crimped 50 and left the other 50 alone. I couldn’t tell a lick of difference between them.
Still curious, I did a similar thing with a 22-250 load, only I did 25 of each. The crimped load shot slightly better by about 3/8”, more interesting is the crimped load had a 20 fps less spread over a chronograph.
I worked up a 7mm Mag hunting load for a buddy. We cut better then ¾” off his load with just crimping.
When I started on a 223/5.56 load (Auto) I always crimped. It made sense on an autoloader. An old fella at the range suggested I try not crimping as they usually shot better. I tried both crimped and not with bullets from 50, 55, 60, 68 and 75. I will honestly admit there were a lot of variables including crimping and I couldn’t tell any difference.
Lastly, I got to thinking maybe the crimped loads have more run out induced by the operation. Took 5, measured them, crimped them and couldn’t see any difference.
I have never been able to duplicate crimping causing accuracy problems in my work. I also don’t crimp the living daylights out of my loads. Now, when I first started loading I had all sorts of problems with a roll crimp, which is very sensitive to case length, that was a negative.
Re: best type of crimp for rifle loads
I've seen test results posted by guys that swear by crimping, usually with the Lee FCD. The results that come to mind, if they are to be trusted, showed some significant improvements in SD (more consistent velocities) but I noticed their starting SDs were pretty poor to begin with. I guess I can see this - a heavy crimp would allow a more thorough ignition before the case lets go of the bullet, much like in a heavy revolver load. In these cases, I saw their crimping as a shortcut. Crimping is much easier than taking all the steps we usually do to insure consistent ignition and pressures, i.e. deburr the flash hole, uniform primer pockets, weigh powder charges, careful sizing to create consistent neck tension, etc.
And then there's the fact that the Lee FCD actually mashes a cannelure into the bullet, usually unevenly if you pull the bullets after crimping and look at them. If nothing else, it takes any variation in neck wall thickness (and there's almost always some of that) and transfers that to the bullet in the form of deeper or lighter 'dents'. That might work fine for 100 yd loads, but at any distance I can't imagine what damage that dent in the bullets does to your BC and flight characteristics.
Years ago I used to use the taper crimp that comes built into many seating dies, mainly because my reloading manual said to do this when loading for semi-auto guns. I learned that the cases have to be exactly the same length or else the amount of crimp varied from case to case. If I got even slightly too much, especially with calibers like .223 and .308, the case would bulge down where the shoulder ends and the straight case wall begins. It's hard to notice most of the time but it can be enough to keep the round from chambering. After having to pull apart 400 .223 rounds because of this problem, I have never crimped another bottleneck round in 30 years since, even for the violent action of an M1A.
I've seen test results posted by guys that swear by crimping, usually with the Lee FCD. The results that come to mind, if they are to be trusted, showed some significant improvements in SD (more consistent velocities) but I noticed their starting SDs were pretty poor to begin with. I guess I can see this - a heavy crimp would allow a more thorough ignition before the case lets go of the bullet, much like in a heavy revolver load. In these cases, I saw their crimping as a shortcut. Crimping is much easier than taking all the steps we usually do to insure consistent ignition and pressures, i.e. deburr the flash hole, uniform primer pockets, weigh powder charges, careful sizing to create consistent neck tension, etc.
And then there's the fact that the Lee FCD actually mashes a cannelure into the bullet, usually unevenly if you pull the bullets after crimping and look at them. If nothing else, it takes any variation in neck wall thickness (and there's almost always some of that) and transfers that to the bullet in the form of deeper or lighter 'dents'. That might work fine for 100 yd loads, but at any distance I can't imagine what damage that dent in the bullets does to your BC and flight characteristics.
Years ago I used to use the taper crimp that comes built into many seating dies, mainly because my reloading manual said to do this when loading for semi-auto guns. I learned that the cases have to be exactly the same length or else the amount of crimp varied from case to case. If I got even slightly too much, especially with calibers like .223 and .308, the case would bulge down where the shoulder ends and the straight case wall begins. It's hard to notice most of the time but it can be enough to keep the round from chambering. After having to pull apart 400 .223 rounds because of this problem, I have never crimped another bottleneck round in 30 years since, even for the violent action of an M1A.
Re: best type of crimp for rifle loads
For a gas gun, a bit of taper crimp works good. Roll crimps requires all the brass be the same case length, limiting oneself to virgin brass or case trimming after every re-sizing. Moly coated bullets need some crimp even in a mild recoiling 5.56 if shooting from a magazine (not single loading).
Mike
For a gas gun, a bit of taper crimp works good. Roll crimps requires all the brass be the same case length, limiting oneself to virgin brass or case trimming after every re-sizing. Moly coated bullets need some crimp even in a mild recoiling 5.56 if shooting from a magazine (not single loading).
Mike
Re: best type of crimp for rifle loads
I asked this very question of the tech support guys at sierra regarding the 7mm rem mag and was told as long as I was full length sizing it was not necessary.
I asked this very question of the tech support guys at sierra regarding the 7mm rem mag and was told as long as I was full length sizing it was not necessary.
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