Seat/ Crimp 45acp & 9mm

I have always seated pistol bullets in one die and crimped them in another die: two separate functions. I have bought separate crimp dies to allow this and current die sets have one die that does both. This leads to my question.

In my old age, I like to have one of those RCBS powder check dies on my turret press or other progressive press. This of course takes up a die station and it can work but I am confronted with the prospect of seating / crimping at one die station. Now I got the dies so thats not the issue here , what I am concerned about is how much degradation of accuracy can I expect when I use one die for this purpose for cast bullets.

I am especially concerned with the 9mm as its so fickle with its already tapered case which if improperly expanded will shave lead off bullets. I am concerned that seating while crimping will foul up the bullets and all I achieve is loss of accuracy.

So the question is , with your patience please: Do you use one die for seat and crimp of cast bullet reloads and is there a down side to that practice as I fear there is.

I thank you for your time and experience

Skip

I uses 1 die to seat the bullet and another to apply the crimp to all of my handgun calibers . that is the preferd method by all experts . you can seat & crimp with the same die if there made for it but the results will most likley be inferior to doing it in 2 operations . one thing that might happen is lead shaving . I havent done it in 1 operation for about 30 years so i kinda forgot all the downsides.
as for the powder check die ! ive never used one for over 200,000 rounds loaded and ive never doubled a powder charge so far (nock on wood) you just have to pay attention to what youre doing.
and dont be distracted while doing so ! if so recheck all of your last operations to make sure everything is ok and then procede

When seating/crimping at the same time the boolit is still moving as it is being crimped, this can cause shaving of lead if the boolit does not have a crimp groove, sometimes even if it does have a groove.
I taper crimp 9MM, 45 ACP, 38SP and 357 in station 4 of my 450B

If you have a single stage press you can setup the crimp die in it and add one operation.

Many years ago I went to the separate crimp operation because of the shaving. It took me all of maybe 20 rounds messed up when I changed my technique. Even though I cast for most handgun calibers the 9's are the most finicky (next to 380) with not to much room for error. For 9's in particular I had to use a 38/357 expander to keep my cast stuff to the right size. Just that added .002 on the expander plug made a world of difference for me. All the calibers that space at the case mouth are always crimped in a separate operation and checked in case gauges. But keep in mind I have 3 single stage presses and just set up one of them all by itself for the final crimp.

I load ALL of my ammo with the seat crimp operations separated. I'll go find or buy an extra seater die for a rifle set just so I can do this.

for my .308's and .30-06's I bought a regular set of RCBS dies and then got a Micrometer seater die also.

The problem you run into with the single die approach is that the bullet is still moving into the case as the crimp is closing.

I never got this to work very well even 30 years ago, and would do the bullet seating in one operation and then remove the seating stem and run the cases back thru the die to crimp. That way I was assured of having a perfectly seated bullet and a perfect crimp. best of both worlds.

Here's another point and please don't take this the wrong way.. Unless you're shooting off a Ransom Rest, I really doubt you'll see significant accuracy degradation and I think your eyesight would limit your accuracy more than any losses incurred by seating and crimping in the same operation.

Also the distances you shoot auto pistols at and the size of the targets probably wouldn't warrant bench rest accuracy.

I shot IDPA yesterday and since I haven't been drilled lately I took twelve shots to move six targets on the dueling tree. They were 5" at 10 yds. and I couldn't believe my misses! I actually had one shot where I hit a target that was 2 targets above the one I was aiming at! Pathetic!

In other words I sucked, and the problem was not my ammo.

I couldn't keep focused on the front sight.

I think you're fine seating and crimping in one step for this type of ammo. But if you must have the powder check die, then you'll either have to live with the one operation seat/crimp or get a progressive with an extra station.

Randy

Hi,
Well...I always looked at it this way,revolver ammo I can seat and crimp in one operation. the revolver boolits usually have a crimp groove and is one reason there was a demand from shooters for custom molds. This problem was the OAL of cartridge and the length of cylinders! Obviously everyone is happy on this point now that custom molds are very reasonable and you can get what you want.

On ACP type cartridges you better seat with 2 dies the last one being a taper crimp die so the rounds will chamber!

Don't worry Randy,you got out and shot your pistol with boolits YOU poured and ammo YOU made,with people of a like mind! There's no down side to that!!! Amigo!

Quote:

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Originally Posted by seagiant

Hi,
Well...I always looked at it this way,revolver ammo I can seat and crimp in one operation. the revolver boolits usually have a crimp groove and is one reason there was a demand from shooters for custom molds. This problem was the OAL of cartridge and the length of cylinders! Obviously everyone is happy on this point now that custom molds are very reasonable and you can get what you want.

On ACP type cartridges you better seat with 2 dies the last one being a taper crimp die so the rounds will chamber!

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These are my thoughts also. While I don't usually do it, seating and crimping cast boolits for revolvers in one step works well for me when I have a nice big groove to crimp in. Pistol rounds are a whole different ballgame.

I've made up a bunch of 9mm (300 or so) and seat & crimp with just one die. The downside is having to clean the seating die with spray oil and Q-tips. When it crimps, it seems to squish the lube out.
Of course, I'm enough of a piddler to reset and check dies all the time on a single stage so, that tells you something too.

Ron