Home Forums Hunting & Shooting BPCR stupid question on using a compression die

I've got the compression die that BACO offers, i've loaded it into my rockchucker and not sure how to set it up. there's no way that i see to set it up so that you can fully stroke the press so i'm assuming you just set it up for the correct compression when the case hits the die regardless of where you are in the stroke of the handle. If thats correct it seems like a good way to damage the case mouth.

or am i missing something obvious?

Tim

hold it-let me back up a step. it's a shiloh compression die not a BACO.

For what this will be worth. I got mine from Buffalo arms, I think that is BACO.
You need to bell mouth a case before you begin, and if you can, run the slug through a sizer die that is a tad smaller than what you are going to be using.You will be using this to measure with later. Measure your powder and put it in the case, if you drop tube,do so. Have your compression die set aways down so when you stroke your loader all the way down it compresses it a good amount, but not all the way. Pull the plunger out and insert the under sized slug into and on top of the powder charge. Look at where the brass is compared to where you want it to crimp, and it will give you a good idea as how much farther down you need to adjust the compression die.That will get you in the ball park.
Now, if you already have your press set up,for the right crimp and OAL, make a dummy load to use when you re-set every thing. It's saved my butt more than once.

Regards,
Knarley

I've been using a compression die for 20 years and that explanation just mystifies the hell outa me!!

Took the words right outta my mouth, you did.

Paul

I'm a bit baffled myself..what cartridge are you loading?

Sorry, but that's how I do it.
Basically, I compress the powder a bit at a time till I get it where I want it. I use an undersized boolit to check my progress. Once it's where I want it, lock it down. (The compression die adjustment nut) Once you got it where you want, thou art done.
Not so hard, huh?

Knarley

appreciate that, i have my numbers and know how much i need to compress. my issue is that with the shiloh die installed in the rock chucker you cannot set it up in anyway that allows a full stroke of the ram. you literally pull down on the ram while watching for the case mouth to make contact with the base of the die and then stop. seems wrong to me.

Tim went and looked at Shiloh compression die pic. on the site.
Looks to me that your going to have to just play with the adjustment up and down of the die and compression plug until you get the full stroke of the rcbs and get proper compression. Only way to do the process. May need some washers under the die, no telling.

I don't have that one but just play with it until you get depth of die, depth of plug and one full stroke of the RCBS.

I haven't a clue on how that one would work. I'd have to play with it a while. How far down will the adjustable ram go in? OK have an idea, just a guess.
Can you adjust the ram, (the part that goes into the case) to the depth where you want the powder compressed to? If what I'm thinking will work, when the case mouth touches the bottom of the die, the plunger will be inside the case, and your powder will be compressed to that depth.
Your compression depth will be set from the bottom of the die to the bottom of the plunger.

Knarley

Just printed a picture of your die. Bear with me, I don't have the most scientific jargon.

The way I figure this thing works is you adjust the main die into your press with the handle all the way down, a case in the shell holder, and spin your die body in(down) until it touches the case mouth. The plunger, the smaller adjustable rod in the center can then be spun deeper into the case, adjusting how far the powder is compressed. The bottom of the main die, to the bottom of the plunger will set the compression depth, and can be measured.

Now if that's not how it works, again, I'd have no other idea.

Knarley

Just back your die out a few turns at a time until you get your full stroke.

Then mark the threads on the die so you can get close when you use it the next time.

i'll get a picture tomorrow, i guess i'm not being clear. picture a standard sizing die and the way your case goes up inside it. now picture the same thing except the case doesn't go up inside the die and you have to stop your stroke when the case mouth hits the bottom of the die.

OK, Tim take the pics. Will you take the die apart for the pic for me to see how it is built. Pull the compression part out of the die.
I kind of think only difference in your die and others is the others have a side and your does not have the sides. You should be able to remove the compression plug from the die. That's one of your adjustments to the amount of compression you want. the die body and compression plug should be two parts, compression plug screws into the die body and die screws into RCBS.

If die is only one piece then the only adjustment your going to have is how far the die is screwed into the RCBS. That should not be the case though cause you need different compression depths for different bullets.

If the die is only one piece your only going to have the one adjustment of screwing the die in or out. Screwing the die out will allow the ram handle to make the full stroke. By that I mean set up as you normal do with that die, no full stroke, now just screw the die out two or so turns which allows the handle to go down which is closer to your full stroke. Keep raising the die until you get the full stroke.
If that's case, I would call Shiloh on Monday and ask how they use that compression die.

Tim I think your being very clear. When the case mouth hits the bottom of the die and you have not completed a full stroke, what do you do to make the RCBS make a full stroke? You unscrew the die some.
You will see the handle go down closer to the full stroke. Keep unscrewing until you reach the breakover point on your RCBS. Mark the threads so you can go back to that same point.

Well...I'll give this a whirl:

1. What you want is when the bullet is seated to the desired point in the case, you can't have any air space between the powder charge and the bullet.

2. Once you have the target cartridge OAL identified, start measuring.

3. Determine how far the base of the bullet will be inside the case. Also figure out the thickness of any wads, lube cookies, etc, that go between the bullet and charge - these add onto the base of the bullet.

4. Say for example, the base of the bullet should be .800" below the case mouth. The lube cookie is .100" thick, and the wads are .030 thick x 2 = .060". So the base of the projectile will be .800 + .100 + .060 below the case mouth, or .960" below the case mouth.

5. To ensure there is no air space between powder and bullet, I will set the compression die (I use Lyman's for my .45-90's) so it compresses the powder .900 below the case mouth. That means during the final bullet seating, there is a slight final compression of .060", ensuring everything is tight with no air space.

6. The Lyman PC die has a long stem on the plug, so it is easy to get the powder compression you want. I use a Redding Ultramag press.

*************

Not claiming this is the ultimate method, but it allows measurable numbers you can record, and duplicate in the future. So far it works on my guns.

And these aren't revolvers! You don't need to CRIMP!!

When you're usually giving advice about powder compression dies for BPCRs, do you EVER mention wads, or how they factor into using a powder compression die properly ?

As noted by another, what's up with alla' this "crimping", and setting dies therefor ?

GTC

Save yourself some grief take out your plastic and buy a Rock Chucker Supreme.The longer stroke is a no brainer for BPCR adjustment. $149.95 will easily remedy your headaches.

Wrong again... The Redding T7 is the best press for bpcr work.