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.

I agree if you want to spend another $149.95

You're right!!

FallCleaning by Rick Mulhern, on Flickr

Best money I ever spent, and I have Sharpsman to thank for his apt advice years ago.
That 149$ will pay you back 10 fold in the convenience factor alone.

nice squared away lash up there, Señor.

GTC

Ok back to topic. You raise the cartridge in the press all the way. Screw the die body in till it almost touches the shell holder. Then you go about setting the depth of the compression stem. You need to have a slight bell on the case mouth to make sure the stem enters the case smoothly, but then you need that slight bell to keep from shaving the bullet base when seating anyway.
If you're loading patched bullets, then get the next size smaller compression stem.

Ranch 13-appreciate your comments but thats exactly my issue. Here's the procedure
1. At full stroke screw down the die until it just touches the shell holder
2. Set depth of compression by dialing or extending the compression stem down (.51 for our situation).
3.insert charged case with wad
4. compress charge-here's where it goes south. you can only raise the ram enough so that the cartridge mouth makes contact with the die. the die is not designed to allow the case to go into the die body. You have to stop raising the ram mid stroke once you make contact with the base of the die.

Ok so that die is designed so that it does not support the case, so just adjust it to compress the powder the proper amount with the ram fully raised.

Now we've come full circle. you can't fully raise the ram with the die threaded into the press.

with no die installed and a 45/70 case in the shell holder and the ram fully raised the case mouth is about an 1" above the top of the press.

Sounds like one hell of a problem you have there.

My guess that' s how it works then. When the mouth of the case touches the die, you are there. Some times on the die I use, the mouth of the case catches the die as it enters, possibly messing up the case. Your die is not going to do that. Set your depth and give it a try.

On another note, to the barkers in the cheap seats.........
Oh, I guess I'm supposed to mention WADS. If you use them, you'll know what to do. And as far a CRIMPING if you want to crimp, go ahead. I like to be able to take the shell BACK OUT of the gun if need be.

Regards,
Knarley

Tim, grab hold of your full length re-sizing die for a bit,....picture the cylindrical "plug" that protrudes from the bottom of your BACO compression setup mounted instead on top of, and threaded through, into the upper / neck portion of your FL die.
The FLR die would of course be bored out, so's to allow the neck some clearance .
Folks have been explaining that sorta' setup,....NOT what you have there,....I really don't know why BACo is even calling it a "Die",....it's not. Using the term die infers that the case will ENTER the thing,...not butt up against it.
To my knowledge hat setup has always been called a "compression plug".

GTC

Maybe this will provide a bit more clarity,....

The custom powder compression die on the right is posed upside down,....mentally flip it around, and one can readily see how much of the thing protrudes ABOVE the fave of your Rockchucker's 7/8-14 bushing,....
Midway between the threaded prtion, and the micrometer head would be about where the floating "plug" sits,....in other words right in the neck area of your case.

Hope this helps



GTC

Mr Crossfireoops,
Mr. Tim doesn't have a BACO it's a Shilo.
The write up on the Shilo states that and I quote:
"You can see everything that's happening". So what I see as happening, the case goes up, over the compression plug/plunger, compressing the powder untill the case hits the bottom of the main body of the "die" and stops. The "plunger" protruding down is what compresses the powder.

With a BACO set up, as you describe, the shell case goes into the "Die" where the "plunger" compresses the powder charge. The problem with the BACO set up is you CANNOT see what is going on, and the case mouth can be distorted by either the "Die" mouth OR more often, the edge of the "plunger" that one cannot see.

I am using the term "die" loosley as the part that screws into the main press body, for it could be called many things. The press doesn't need to have a full stroke to do it's job with the Shilo set up, but it would certainly be nice as at least a reference.

The OP, Mr. Tim was asking about setting his powder compression set up. Wads, crimping, lube,grease cookies, neck tension, and all the other "voodo" that we do, is also part of the loading of BPCR, can be touched on at a later date.

One step at a time, one step at a time.

Regards,
Knarley

Angels dancing on the head of a pin.
Nomenclature dispute,....
Small beans, as I've never BOUGHT a die from either outfit,...I make all of my own. That Micrometer die's a good example, as is the 2.6 body die beside.

There are more than a few folks posting here that use all sortsa' tooling and parts built here, as well.

You might want to quiz "Mr. Tim" about that.


.....the plungers in those dies are WAY to sharp / squared off on their lower radius,....putting a nice round profile on those edges STOPS the case mouth deformation bug DEAD in it's tracks. Having a wad seated with a slightly concave upper face means squat.

GTC

unfortunately i think this is designed to be used without coming to full stroke. i believe i'll just buy a compression plug (as you have all described) that fits an RCBS expander die. My intent was to make sure i wasn't missing something obvious which it appears i'm not.

Appreciate all the input and opinion.

Tim

Tim - hopefully this might help clarify what you are looking for . . . First picture is of my assembled compression die - set up for a 45-90. Second pic is of the compression die with the "plug" removed and set beside the "body".

Assembled die


Die with plug removed


Mine is a "custom" die made by a friend of mine (not positive, but I think the body is from an FL die). The body is an extra he had laying around and he made the plug. It is adjustable by moving the "ring nut" on either the top (plug) piece or on the bottom (body) piece. For a 45-70, either the top "ring nut" would need to move toward the top of the plug 0.4", or the bottom "ring nut" would need to move toward the top of the body 0.4". The bottom of the compression plug has a slight chamfer to avoid dinging up the mouth of the cartridge. This die allows the cartridge to be inserted into the die as far as necessary to get a full stroke of the press. adjustable for everything from 45-70 to at least 45-120 . . .

Hi Otter,

the problem is that that is not what i'm looking at. the shiloh die does not support the case (the case does not go into the die but stops at the base of the die.

I should have said at the onset that i've been reloading for 10 years or so and have a good grasp of the basics. but this situation is something i have not run into before.

Appreciate your input-

Tim

Reading the description of Shiloh's compression die it says something to the affect that it keeps everything out in the open where you can see it.
Then looking at the picture, it becomes rather evident that you screw the die into the press until you see the bottom of it, then adjust the compression stem to compress the powder to the desired depth. So no you would not raise the ram completely, you will have to go slow and pay attention or yes you may mash a case mouth in if you jam the ram up without looking at what you're doing.
Did you call Shiloh and ask them about how to use the die?
Were there no instructions included with it?

i haven't called them and unfortunately it came in nothing more than a plastic bag.

Appreciate all the comments.