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Lee Factory Crimp and seating depth

I was sitting on my throne (aka toilet) the other night and grabbed a Lee Reloading catalog that I had laying around to thumb through.

When I got to the crimping die, in the description it said something that was interesting. It stated (I'm paraphrasing) that the reason one would seat a bullet to the lands is to create consistent pressure when the round goes off. Using the crimping die negates the need to seat the bullet out to the lands.

Now I reload for an AR-15, a M1 Garand, and my bolts. Based on what Ive read on the interwebs it seems most never crimp for the semi-autos but a few do and swear by it. Crimping for a bolt apparently is never done except for the occasional hunting load.

So.. is this just marketing BS or is there some merit behind this?

In my own experience, I've been putting a light crimp on my AR loads but have not really experimented with crimp vs no crimp.

I have noticed that my reloads on the m1 garand grow ever so slightly if I chamber a round and then eject it without firing so I have been thinking about picking up the crimp die for the garand. I may have to experiment with one of my bolts.
 
I wouldn't (crimp that is) for bolt-action rifles. It adds yet another potentially troublesome variable to the mix and sooner or later will affect neck tension through work hardening the brass.

Having said that, there is evidence it works well and reduces both group size and MV spreads in some cartridges, .30-30WCF being a prime example. Some years back I found it worked well too in 7.62X39mm, a cartridge that has a habit of producing large ES values with everything below absolute max pressure loads.

Gas guns may be another matter of course due to the rough handling the round gets in being chambered.
 
+1 on Laurie's comments! Ain't no way in heck I'd crimp a bolt gun round especially if ultimate accuracy and target shooting is your thing. In fact, I don't even crimp for my AR because I've tested before with and without crimping and my groups are tighter without a crimp on the bullet into the casing. Since I seat the bullet into the lands on some of my rifles, the last thing I want is a form of a restriction on the release of the bullet. Crimping does serve a useful end with Semi-Autos even though I seen mixed reviews even in that category. Guess ya gotta do what makes you happy and works for you.
 
Shynloco said:
Since I seat the bullet into the lands on some of my rifles, the last thing I want is a form of a restriction on the release of the bullet.

I believe the point "LEE" was making is that by using their crimp die you would not have to seat the bullet out to the lands. You could stick with published COAL data.

They said the reason one would seat to the lands it to create consistent pressure. Crimping would achieve the same thing, assuming that is the reason folks seat to the lands in the first place.

I am not a competition shooter and am still relatively new to reloading (about 18 months now). Based on my reading it seems that one of the problems with seating to the lands is having to "chase" the lands as your throat erodes.. seating further and further out.

If one could achieve consistent pressure without having to seat to the lands, then that would seem to be the better approach.

Ultimately I will probably experiment with this myself. I didn't expect to find too many on this board that crimp their loads but I was curious what others thought of "LEEs" claim that using the crimp die would negate the need for seating to the lands.
 
Ultimately I will probably experiment with this myself. I didn't expect to find too many on this board that crimp their loads but I was curious what others thought of "LEEs" claim that using the crimp die would negate the need for seating to the lands.

Experimentation is always good! Remember though that many if not most precision shooters don't seat their bullets so they're into the lands. Traditionally, it was believed that this is essential for VLD and other secant ogive style bullets, although it's since been discovered that VLDs often shoot well with really large jumps of 0.040-0.080". Many tangent ogive bullet designs such as most Sierra MatchKing models are very jump tolerant indeed, and Berger Bullets has recently introduced a high-BC 175gn Tactical OTM in 0.308" that is specifically designed for SAAMI 2.8" COAL .308W rounds used in magazine rifles and with long throats that also remains stable as it passes through the trans and sub sonic flight barriers if used in a 1-10 to 1-11.25" twist barrel. Berger has also moved rapidly into introducing its 'Hybrid' designs that give the long aerodynamic noses of VLDs allied to a tangent nose section to shank junction that makes them very jump tolerant.

So, while the Lee factory crimp die probably increases 'bullet pull' (case-neck grip) and may, in fact probably, makes it more consistent on so-so factory brass, precision shooters get their consistency through choice of brass make, measurement, selection/batching and case preparation. While I don't disbelieve Lee's claims, the crimp die will never deliver the results that carefully selected and batched, neck-turned etc cases will produce when used in a suitably high quality rifle. For the accuracy-orientated deerhunter and similar using out of the box R-P etc cases, the Lee may be well worthwhile trying, although it'll shorten case life due to the extra work-hardening.
 
I use one of the LEE factory crimp dies for ammo used in a slam feed gas gun. Some guns come with the M4 feed lips and devour ammo without any problems. Some guns are not equipped with this and will probably have some issues from time to time getting ammunition from the magazine to the chamber. This die when used properly helps to eliminate bullets being shoved back into the case when ammo is being fed if the gun in question has the older style feed lips. Most powders works their best when at or near maximum pressure, a crimp helps to raise that pressure. If you get one of the LEE factory crimp dies, trash that LEE lock ring and put on a reputable split lock ring of some other manufacture. Also this die works when your case lengths aren't all exact the same also, because it does a "neck down" type of crimp.
 
I did a good bit of experimenting with the Lee Factory Crimp Dies a while back. My experimenting was with old military bolt and semi auto rifles. With most of the bolt rifles they have throats that are a mile long and the bullet has to jump a long ways. I found that using what I call a medium crimp, fingers half way between open and fully closed, worked best. It definitely increased accuracy in 90% of the rifles I tried it with. I was shooting a modified vintage military rifle match we called old men's match. It was bench rested rifles at 100 yards and carbines at 50 yards for score. There were some "Bench Rest" shooters involved and they thought they knew everything. I never told them I was crimping but I did hear them making statements like "That is just stupid taking a perfect match bullet and squeezing it and distorting it and expecting it to shoot accurate." They never could figure out how I was always shooting their paints off in these matches. You never know until you try it yourself.
For the semi-autos I used the crimp mostly for assurance that he bullet did not move but accuracy was also better.
 
I use the Lee Crimp Die on any traditional handgun cartridges, but only crimp rifle cartridges that will be fed from a tubular magazine to prevent bullet set-back from the spring and recoil pressure. Until you get to the big boys (.375 and up) proper neck tension works just fine. Case length becomes even more critical when crimping so that the crimp is uniform. Some may feel it is a benefit, but it's just an unnecessary nuisance for me.
 
Stupid question number 29, wouldn't a smaller expander diameter increase bullet grip. The RCBS AR Series .223 dies have a taper crimp vs the Lee FCD.

Below the Lyman type "M" expander has .003 bullet grip and many AR15 shooters use this expander. Then a taper crimp is applied to aid feeding.
ohIUcpd.png


Below some pistol shooters use a undersize die to increase bullet grip. The cartridge below is wasp waisted and has a slight taper crimp.

MfcwIQB.jpg


Bottom line you do not need to crimp to increase bullet grip.
 
Yes brass springs back, more so, as it is work hardened from shooting, expanding to the chamber, and being resized back down for reloading. This is why many shooters anneal their brass to keep consistent neck tension and accurate sizing dimensions when bumping back shoulders.
I never use the Lee FCD for bolt actions, as I tune the loads for whatever neck tension I am using and try to keep it as consistent as I can.
Is it needed for semi-autos? Tons of people do not crimp them and do just fine. I anneal my cases to keep the neck tension consistent and tight on my semi-auto rifles, and I do lightly hit them with a Lee FCD just for peace of mind, probably more out of paranoia of having a bullet pushed back in the case, than actually really needing it. Be careful with this crimp die as it does not take much of a bump to compromise the integrity of the jacket and bullet, and tune your loads accordingly, because the Lee FCD, like any crimp die, does change the pressure curve, like seating depth, powder charge, or most anything else. YMMV
 
I was sitting on my throne (aka toilet) the other night and grabbed a Lee Reloading catalog that I had laying around to thumb through.

When I got to the crimping die, in the description it said something that was interesting. It stated (I'm paraphrasing) that the reason one would seat a bullet to the lands is to create consistent pressure when the round goes off. Using the crimping die negates the need to seat the bullet out to the lands.

Now I reload for an AR-15, a M1 Garand, and my bolts. Based on what Ive read on the interwebs it seems most never crimp for the semi-autos but a few do and swear by it. Crimping for a bolt apparently is never done except for the occasional hunting load.

So.. is this just marketing BS or is there some merit behind this?

In my own experience, I've been putting a light crimp on my AR loads but have not really experimented with crimp vs no crimp.

I have noticed that my reloads on the m1 garand grow ever so slightly if I chamber a round and then eject it without firing so I have been thinking about picking up the crimp die for the garand. I may have to experiment with one of my bolts.
I have seen substantial improvement in 30-06 and 300 WSM by simply applying as much roll crimp as the bullet:case will tolerate. Each is different and it requires a little practice with the “feel” of resistance to be consistent. But, it works, IMO.

I do have a Lee FCD in my .44 die set. I’m looking forward to using it when I get me some WLP primers.
 
I brought up this old thread to see if anyone could show me some pics of what you would think to be the perfect amount of crimp on .223 rounds from the Lee die. Thanks!
 
I crimp in several of my hunting rifles which use Hammer bullets. These are copper bullets with PDR grooves in them (parabolic drag reduction). The bullets have very little bore friction and the Absolute hammer is a bore rider type in which the ogive doesn't engrave which reduces start pressures even further. I always crimp the AH bullets in order to get consistent ignition. I have experimented quite a bit and found that the AH always benefits from a light to moderate crimp which the normal Hammers may or may not. Having shot Barnes and hammers for about 30 years now I have also found they like plenty of jump. I usually start at .050 off the lands and in every case but 2 my rifle likes this jump. The exception here is my 280AI which likes .030 and my 338 RCM which has a short mag and jumps .2+ depending on which bullet I shoot. With this said, every one of these rifles shoot .5 or better and in some cases under .1. Many hammer shooters crimp everything with great results but I test the effectiveness of crimping. Sorry for being long winded but testing is the only way to know. I crimp all semi auto ammo, period.
I suspect seating into the lands would also prevent primer impulse from unseating the bullet before powder ignition but I have not tested this.
 
I have used it for 9mm, 38sp. A Lee tech said send in a couple 20p dummy rounds and 30 dollars plus shipping they would make me a custom 20p crimp die. I'm considering it.
 

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