9mm crimp

[Dieselhorses]

If a 9mm luger fires from a semiauto pistol/rifle, why on Earth do they sell factory "crimp" dies? I accidentally ordered one of these when I was, in fact, meaning to order the "tapered crimp" die. Also, why do they sell .355/.356 bullets when everyone says that they are too small for 9mm, and they prefer .358?

[lotech]

You don't need a FCD if you're doing everything right. I've found a taper crimp die works fine for cast bullets in the 9mm.

.355" bullets will work just fine in 9mm as long as they are jacketed bullets, not cast. Cast bullets need to be a little larger in diameter than bore size and that's not for just handgun cartridges, it applies to rifle bullets as well. Dependng on the gun, .357" or .358" diameter bullets seem to work best. There are always exceptions; maybe there are some 9mm pistols that do well with .355 cast bullets, I'm just not aware of any.

.356" cast bullets will work in 9mm, but you'll likely see less than ideal accuracy and it may be necessary to regularly remove bore leading, but they're safe to use.

[Dieselhorses]

Thanks, lotech for info. Just trying to find the purpose of the fcd. Would the fcd be a "roll crimp"? And would seem to be for rimmed cartridges? Sorry, even if I don't currently use something, i want to know it's applications.

[mehavey]

FCD for rimmed/roll is different than FCD for straightwall rimless (e.g., your 9mm).
I prefer standard roll crimp for former, and only use the latter for cast Legend/Bushmaster (etc)

[lotech]

Thanks, lotech for info. Just trying to find the purpose of the fcd. Would the fcd be a "roll crimp"? And would seem to be for rimmed cartridges? Sorry, even if I don't currently use something, i want to know it's applications.

I have found some very limited usefulness for the FCD when loading .32-20, a cartridge I only load every few years. Winchester .32-20 brass and Remington .32-20 brass are considerbly different in length, at least the batches I have are different. After seating bullets, I don't re-adjust the crimp die for the two different lengths, I just use the FCD. This probably wasn't the intended purpose for the die, but it has worked well for me. If you examine one of these dies and play with it a little on some dummy cartridges, you'll quickly see how you could easily get into trouble by overcrimping, distorting the case neck and resizing the bullet. Many handloaders crimp way more than is necessary anyway. The FCD makes overcrimping much easier. If you can get by without this die, and you probably can, that's the best approach. However, used properly (minimally), it shouldn't do any harm, but only you will know if that's true for your situation.

[Dieselhorses]

FCD for rimmed/roll is different than FCD for straightwall rimless (e.g., your 9mm).
I prefer standard roll crimp for former, and only use the latter for cast Legend/Bushmaster (etc)

So an FCD does something between a roll crimp and a taper crimp?

[mehavey]

https://support.leeprecision.net/en/...mp-explanation
. . . . The type of crimp on the die depends upon the type of cartridge.
. . . . With cases that headspace on the case mouth such as the 45ACP,
. . . . the die essentially reduces the outer diameter of the case mouth
. . . . into the bullet. On other cases, a roll crimp is applied.

and in actuality, two dies can be of completely different design depending on specific cartridge

[Dieselhorses]

https://support.leeprecision.net/en/...mp-explanation
. . . . The type of crimp on the die depends upon the type of cartridge.
. . . . With cases that headspace on the case mouth such as the 45ACP,
. . . . the die essentially reduces the outer diameter of the case mouth
. . . . into the bullet. On other cases, a roll crimp is applied.

and in actuality, two dies can be of completely different design depending on specific cartridge

makes sense. I believe the .45 acp is straight walled but the 9 is slightly tapered so not dependent on head spacing in chamber?

[mehavey]

Both headspace off the mouth.....

When you have rim, headspace off the rim.
When you have shoulder, headspace off the shoulder.
When you neither rim nor shoulder . . .

[Huskerguy]

I guess I am slow today and not completely following your question.

The Lee FCD which I use is a roll crimp for 38/357, i.e. revolver rounds and is a taper crimp for my 9mm. Some people like them, others swear at them and adjust their crimp with their seating die which I also do. The die manufacturer builds that into the die so you aren't going to roll crimp with a 9mm die set.

The crimp on a 9mm, for me, is the most critical aspect of loaded that round. Too much or not enough crimp lead to problems so using the data measurements in a book are key, not just going by looks like I can with a 38.

As for bullet size, the answer given above is spot on. Much depends on the material of the bullet. I reamed my Lee sizing dies out so my coated bullets size right at .3575 which works for my CZs.

[mdi]

"The crimp on a 9mm, for me, is the most critical aspect of loaded that round. Too much or not enough crimp lead to problems so using the data measurements in a book are key, not just going by looks like I can with a 38".


I've been reloading semi-autos for a while and I do not crimp in the "normal" fashion. Since neck tension is what holds semi-auto bullets in place, there is no need to "swage" the case tightly on the bullet. I tried measuring case mouth OD post "crimping", but found little value. I just deflare the case mouth enough to get 100% plunking using a taper crimp die (aka "deflaring die"). This has worked quite well for me on 32 ACP up to 45 ACP in 11 semi-auto handguns. K.I.S.S.! Don't overthink "crimping" semi-auto handloads...

[45_Colt]

If a 9mm luger fires from a semiauto pistol/rifle, why on Earth do they sell factory "crimp" dies? I accidentally ordered one of these when I was, in fact, meaning to order the "tapered crimp" die.

I take it this is a Lee FCD? If so they only sell the carbide FCD for the 9mm (may change down the road).

In this case it does two things. 1st is that it removes any flare from the case mouth via a taper crimping. And depending upon how the die is adjusted, further taper crimp the case mouth into the bullet. Which usually isn't required.

The 2nd part of the Lee carbide FCD is that there is a sizing ring, made of carbide, in the lower part of the die. Its purpose is to reduce the case size, even swage the bullet if oversize, so that every round will seat/plunk into a properly sized chamber.

There is a real mixed response to whether this die is necessary or not. It does have its pulses and minuses. So it really comes down to whether the user wishes the secondary sizing or not.

Doing a separate taper crimp is helpful when seating cast bullets. As it helps prevent the slicing of lead off the bullet as a single seat/crimp die can do.

45_Colt

[fredj338]

They sell 0.356 because people buy them. All my 9mm will run a 0.356, but i size 0.357 just to be sure in multiple, modern guns. I found no accuracy gain or leading reduction with 0.358.

[Dieselhorses]

So, I gather from all responses (which I am grateful for!), that it really depends on what a certain gun likes. From a global standpoint, I'll just treat my 9mm rounds as 45 acp's and do a slight taper crimp. Didn't mention but I'll be shooting these from a BCA 10.5" upper. Starting to wonder if I could load my lighter cast .358 pills for 9mm.

[wv109323]

IIRC, the Lee FCD was originally sold to increase accuracy mostly on rifle cartridges. It was suppose to correct bullet run out. It was to "hold" the case straight and then crimp the bullet concentric with the centerline of the case/bore.
I don't think there is any advantage of the FCD over a taper crimp die on pistol cartridges.

[243winxb]

From Lee

The carbide factory crimp die crimp style is a taper crimp for all auto loading handguns.

https://support.leeprecision.net/en/...ie-crimp-style


The rifle type is different.

[AlaskaMike]

The instructions that come with your 9mm carbide factory crimp die are much more concise and clear than the misinformation and confusion contained in a forum thread.

Just a suggestion.

[Dieselhorses]

The instructions that come with your 9mm carbide factory crimp die are much more concise and clear than the misinformation and confusion contained in a forum thread.

Just a suggestion.

They are. They just didn't say anything about that it's recommended to keep the bullet from entering the case during cycling, affecting accuracy or for pressure purposes.

[charlie b]

Probably because those are the reasons you use a crimp die. The links are Lee descriptions of the crimp dies. Lee does go a bit overboard with the rifle die and accuracy claims. I have had a couple rifle loads that did better with a crimp, but most do not.

I reloaded many years without ever crimping a load. Now I crimp all pistol loads, but no rifle loads (all bolt action).

https://leeprecision.com/reloading-d...tory-crimp-die

https://leeprecision.com/reloading-d...tory-crimp-die

[mdi]

They are. They just didn't say anything about that it's recommended to keep the bullet from entering the case during cycling, affecting accuracy or for pressure purposes.

In semi-auto cartridges the neck tension keeps the bullet in place, not necessarily the taper crimp. I have been reloading semi-autos for roughly 28 years and do not crimp any. I just deflare the cases with the "deflaring die" (aka taper crimp die). With proper neck tension there is normally no set back, at least for the 4 semi-auto rounds, in 9 pistols, that I reload.

There is often a lot of "confusion" in threads about Lee FCDs. There are basically two types; for rifle/bottle neck cases a collet crimp die is used (also for a few straight walled cases, I have one for 44 Magnum). For "straight walled" cases a "post crimping sizing die" is used, an adjustable crimp die with a carbide ring for sizing before/after a crimp is applied. I am using a Lee FCD for my 32 H&R now because that is what came with the set and I haven't researched any profile or standard roll crimp dies. My handloads don't need any resizing but that's what I have for now, and my cast bullets aren't swaged down by the ring...