Lee factory crimp die

[canuck4570]

would like to know the pros and cons of the lee factory crimp die

 

[jimbo88mm]

Pro:
Easy to setup and seems to do a better job then a roll crimp that some seaters have.

Cons:
Adds another step
Little reason to crimp on most loads.

With my M1 and AR I saw no difference. I did seem to help a little on a 243 that had a shot out barrel but that barrel has since been replaced. I currently do not crimp any of my loads.

 

[markm87]

One of the pros for me is that I can put a light crimp on matchkings for our gas guns. Might not be necessary, but mine is in a Dillon. So it's no extra work, and it doesn't hurt accuracy.

 

[Fat Albert]

Since the die works by the shell holder pushing on the collet to form the crimp the die can be trick into crimping longer cases with a spacer(stack of washers) sitting on the shell holder. You can uses a 243WSSM crimper with the right amount of washer to crimp any 6mm case longer than a 243WSSM (243Win-6mmRem-6/284Win-6mm/06). With the 250 Sav die you can do 257Rob-25/06-257 Weaterby. the 308 Win will work with 30/30-30/40 Krag-30/06-300Win mag and 300 Weatherby.

 

[2506]

I shoot a lot of old military rifles and they have looooooog throats. No way to get close to the lands and still work through the magazine. I have found that the use of the Lee Factory Crimp Die really increases accuracy over rounds not crimped for me. It also improved accuracy in my AR and M1 Garand. Even heavy crimps on match bullets DID NOT ADVERSELY EFFECT ACCURACY.

The Lee Factory Crimp Die for pistol round is great. It makes for almost no malfunctioning problems in semi-autos for me.

 

[steve4102]

would like to know the pros and cons of the lee factory crimp die

Which one, the rifle or the handgun?

 

[jlow]

I shoot a lot of old military rifles and they have looooooog throats. No way to get close to the lands and still work through the magazine. I have found that the use of the Lee Factory Crimp Die really increases accuracy over rounds not crimped for me. It also improved accuracy in my AR and M1 Garand. Even heavy crimps on match bullets DID NOT ADVERSELY EFFECT ACCURACY.

The Lee Factory Crimp Die for pistol round is great. It makes for almost no malfunctioning problems in semi-autos for me.

Ok, but has anyone actually done a study to test whether it affects ES and/or SDEV which to me is different than accuracy at least in terms of what is normally done i.e. at 100 yards? It seems that a Lee crimp will likely change the diameter of the bullet bearing surface at least the area inside the case. Not making a judgement call as to whether this is good or bad but asking whether someone has actually done a through study and what are the results?

 

[markm87]

I chrono'd loads with and without the FCD... and with a taper crimp too If I recall correctly. I couldn't find anything that stood out one way or another.

I didn't have a high end Chrono though..

 

[steve4102]

I shoot a lot of old military rifles and they have looooooog throats. No way to get close to the lands and still work through the magazine. I have found that the use of the Lee Factory Crimp Die really increases accuracy over rounds not crimped for me. It also improved accuracy in my AR and M1 Garand. Even heavy crimps on match bullets DID NOT ADVERSELY EFFECT ACCURACY.

The Lee Factory Crimp Die for pistol round is great. It makes for almost no malfunctioning problems in semi-autos for me.

Ok, but has anyone actually done a study to test whether it affects ES and/or SDEV which to me is different than accuracy at least in terms of what is normally done i.e. at 100 yards? It seems that a Lee crimp will likely change the diameter of the bullet bearing surface at least the area inside the case. Not making a judgement call as to whether this is good or bad but asking whether someone has actually done a through study and what are the results?

Here is one.

http://www.accuratereloading.com/crimping.html

 

[jlow]

Thanks! An interesting study. Not quite sure what that first set of numbers are , not labeled? The N-size of the study is pretty small (5) and at least looking at the three main numbers – average MV, ES, and SD, does not seem to have any significant effect one way or the other – thanks!

 

[steve4102]

Thanks! An interesting study. Not quite sure what that first set of numbers are , not labeled? The N-size of the study is pretty small (5) and at least looking at the three main numbers – average MV, ES, and SD, does not seem to have any significant effect one way or the other – thanks!

From the test.
I loaded 50 identical rounds for each rifle, 25 of which were crimped and 25 were left without crimps. I tried to put a reasonably heavy crimp on, although none of the bullets had a crimp groove. I fired all of the them as 5 shot groups, over an OEHLER Model 43 PBL.

The test size was 25 rounds crimped and 25 rounds not crimped for each cartridge for a total of 50 rounds per cartridge.

The first numbers are group size for five rounds. In the 223 un-crimped five shot group 1 measured .523 inches, Group 2 .596 inches etc. for a 25 round average of .618 inches.

 

[canuck4570]

thank you
just received my lee factory crimp die for my 375 h@h

 

[queen_stick]

Thanks! An interesting study. Not quite sure what that first set of numbers are , not labeled? The N-size of the study is pretty small (5) and at least looking at the three main numbers – average MV, ES, and SD, does not seem to have any significant effect one way or the other – thanks!

From the test.
I loaded 50 identical rounds for each rifle, 25 of which were crimped and 25 were left without crimps. I tried to put a reasonably heavy crimp on, although none of the bullets had a crimp groove. I fired all of the them as 5 shot groups, over an OEHLER Model 43 PBL.[/i

The test size was 25 rounds crimped and 25 rounds not crimped for each cartridge for a total of 50 rounds per cartridge.

The first numbers are group size for five rounds. In the 223 un-crimped five shot group 1 measured .523 inches, Group 2 .596 inches etc. for a 25 round average of .618 inches.

Steve,

That's interesting stuff. Thanks for posting the link. Did you write that article?

 

[jlow]

Thanks! An interesting study. Not quite sure what that first set of numbers are , not labeled? The N-size of the study is pretty small (5) and at least looking at the three main numbers – average MV, ES, and SD, does not seem to have any significant effect one way or the other – thanks!

From the test.
I loaded 50 identical rounds for each rifle, 25 of which were crimped and 25 were left without crimps. I tried to put a reasonably heavy crimp on, although none of the bullets had a crimp groove. I fired all of the them as 5 shot groups, over an OEHLER Model 43 PBL.

The test size was 25 rounds crimped and 25 rounds not crimped for each cartridge for a total of 50 rounds per cartridge.

The first numbers are group size for five rounds. In the 223 un-crimped five shot group 1 measured .523 inches, Group 2 .596 inches etc. for a 25 round average of .618 inches.

Thanks for the clarification, I stand corrected. Was too focused on the average/ES/SDEV. Very nice study, seems pretty clear cut that there was no significant changes in all values examined.

 

[Heavies]

I shoot a lot of old military rifles and they have looooooog throats. No way to get close to the lands and still work through the magazine. I have found that the use of the Lee Factory Crimp Die really increases accuracy over rounds not crimped for me. It also improved accuracy in my AR and M1 Garand. Even heavy crimps on match bullets DID NOT ADVERSELY EFFECT ACCURACY.

The Lee Factory Crimp Die for pistol round is great. It makes for almost no malfunctioning problems in semi-autos for me.

Ok, but has anyone actually done a study to test whether it affects ES and/or SDEV which to me is different than accuracy at least in terms of what is normally done i.e. at 100 yards? It seems that a Lee crimp will likely change the diameter of the bullet bearing surface at least the area inside the case. Not making a judgement call as to whether this is good or bad but asking whether someone has actually done a through study and what are the results?

I believe with a heavy crimp, with the LFCD(rifle), the bullet's bearing surface is slightly indented. This indented area is only applied to the top of the case neck to ~1/32" down, and to the area, of the bullet, near the case mouth. I don't think that it effects the bullets accuracy much when used for hunting or semi auto use, but for match/benchrest effects may or maynot appear. Being that benchrest type shooting does not require rough handling of rounds, and generally single loading, the crimp is not really needed. So, IMHO, this die is valuable for field and semi-auto use.

I have seen devices that can attach a torque wrench to the handle of the press, thus enabling one to put an approximately consistent crimp onto the shell. I had made a homemade device to do this very thing, but have not had time to fully test the theory.

 

[steve4102]

Did you write that article?

No, I didn't right it, it was done by the guys over at Accurate reloading.

http://www.accuratereloading.com/