Crimp And Pressure Warning Signs Questions?

[Chills1994]

Okay, I did a search for "crimp". Then I did a search for "pressure signs".

Instead of starting two different threads here in the BEginner's forum, I figured I just post 'em all in one.

The search on crimp gave quite a few pages of results, but basically I want to know is:

When you measure your loaded round with your dial vernier calipers, do you use the narrow knife edge part on the shiney ring at the case mouth (the shiney ring is where the crimp die pressed it into the bullet)?

OR, do you use a case gauge only, and go with that, adjusting the crimp die until the loaded round drops in and out just fine?

What kind of dimensions are we talking about here for:

Jacketed bullets in:

9mm?

40?

45?

How about for lead bullets in same calibers?

I hear people talke about pressure signs, but what are they? Do they just refer to the empty shell casing?

Thanks,

Chills

[AlamoShooter]

Chills

What loading book did you start with? If you do not have a book like Hornady's big book or Sierra, you an get an older copie from Ebay. this will give you most of the common Knowledge information. Not that any question on the forum is not ok it is just that information is power and you should be able to filter out good advice from bad.

The most common sign we use for presure is the 'primers' = if the primer is blown to pices as the brass ejects, thin that would be HIGH. normaly it starts with the primer going flat and you can not see the grove from brass to pimer.

To mesure the loaded round for crimp you need somting better than the calipers. yes the final round should just drop in the case gage and fall out. = for normal action shooting that is.

if the crimp lets the bullet move when yo push the round lead end into a wood bench = thin it is too light. for the Auto and revolver a too light crimp will let the lead part of the bullet float in the brass and jamb up when it is on the ramp -auto- or as the clylinder turns -rev-.

to mesure the crimp you would need a micromiter to do it right. ' No real need to '

You could use a bullet puller a kenetic one is good, with it you can wack a block like you are trying to pull the bullet. if it comes out easy you may want more cirmp if when it is pulled and you see a deep ring on the lead = thin tha tis too much.

With the plated bullets like the Berry or Rainer if you mark up the bullet with a hard crimp the groups coud go to as big as 24" just form too much crimp. A book will not tell you that part though. Plenty of photos are availabel of what too much presure looks like. I can take some if you like or I could mail you some old brass. just send a PM

Jamie

Edited January 31, 2006 by AlamoShooter

[XRe]

The most common sign we use for presure is the 'primers' = if the primer is blown to pices as the brass ejects, thin that would be HIGH. normaly it starts with the primer going flat and you can not see the grove from brass to pimer.

I'll add to this - sometimes you see some primer smear, which, as it gets dramatic, looks like Jamie describes, almost as if you've poured molten metal into the primer pocket (which is roughly what's happened, at that point). A slightly flattening of the shoulders of the primer is generally OK because of the dynamics involved when the gun is fired (the primer actually backs out, and is then reseated by the case moving backwards against the breech face immediately afterwards). You may also see some primer flow around the firing pin head into the firing pin tunnel - which may then get scraped off as the case is extracted.

Primer flow and severe flattening are to be avoided, no doubt. However, that said, if you're using Federal primers, they seem to exhibit those signs prematurely, and you can't really use them as a gauge. A harder cupped primer (Winchester, CCI - I've never used Remingtons...) would give you a better idea of what's going on.

To mesure the loaded round for crimp you need somting better than the calipers.

You'd like to use a micrometer, to prevent misalignment. However, I use calipers very carefully, and don't seem to have a problem. It's just delicate, and you should measure several time to be sure - right at the extreme end of the case. And, recheck anything that doesn't immediately make sense...

As Jamie says, crimp somewhat depends on the bullet and load - some magnum loads *require* a strong crimp to insure complete ignition of the powder charge. For action pistol sports, though, rarely would you need something real strong. As Jamie said, make sure you don't have a setback problem - not only can it result in jams, but it can also cause pressure spikes and - in a worst case scenario - a detonation/explosion. If you have that problem, you may also check your size die, and insure that it's sizing the case properly to provide proper bullet "pull" or tension - crimp can't solve all of those problems.

In my .40 loads, I crimp to .420 - which is basically a thousandth under the size of the bullet plus 2x the thickness of the brass. That seems to keep everything correct. Brian will tell you that the purpose of the crimp die is just to remove the bell you already put in the brass, and that's a good starting point. If you need a lot of crimp, something else is probably wrong...

With my Open gun, I crimp about 2-3 thousandths - it seems to help with ignition, and doesn't hurt accuracy in that gun. I crimp my .38 Super Comp loads to .378 (the brass is thicker than the .40...)

[Front Man]

I happened to run on to a factory loaded 38 Super a couple of years ago and took it home to compare the factory crimp to my own reloads.

The factory loaded stuff had a lot more crimp than I use and I think I use a lot!

I'd rather sacrifice a little accuracy in favor of safety.

FM

[RC1]

Here is a quote from BENOS,(Mar 28 2005, 04:23 PM) , that might be helpful

"Back in the ol' days, when we didn't have the luxury of crimping as a separate operation, we'd adjust our combination seating/crimping die to remove the flare, hopefully without cramming the case mouth into the bullet too much. Then Mike Dillon came along and built machines that seated and crimped in separate stations! Wow - crazy stuff. And then he even started making dies that crimped auto-pistol cartridges correctly, that is to say didn't actually "crimp" at all, but simply removed the flare from the case, laying the (flared) case mouth perfectly flat against the bullet.

Unfortunately, somewhere during the taper crimp die's evolution (from the roll crimp die), no one bothered to rename it so as to not mislead folks, for generations.

Roll crimping should do just what the name implies - the case mouth is slightly (or sometimes drastically, in the case of a heavy recoiling revolver) rolled into the bullet's cannelure. Which helps prevent the bullet (in the unfired rounds) from moving forward in the case in a revolver. Since revolvers typically headspace on the rim, as long as the roll crimp doesn't deform the bullet's bearing surface, no harm is done with even a heavy roll crimp.

Since autoloaders headspace on the case mouth, however, the case mouth should never be crimped so that the case mouth penetrates into the bearing surface of the bullet. So in the case of an autoloading pistol, the "taper crimp die" should never actually crimp the case mouth into the bullet in any way whatsoever. The roll of the taper crimp die is to remove the flare previously applied to the case (in order to seat the bullet without shaving copper/lead) - returning the case mouth so that is snug down on the bullet, but not crimping the case mouth into the bullet at all.

After some experience one can learn to "see" (without tools) if this has been done correctly. (Either too much or too little.) But until then a good set of calipers will guide you as you adjust the "Flare Removing" die. Using the thin part of the calipers (near the tip), measure the loaded, flare-removed round's case mouth at the very end of the case. The result should be the sum of the bullet's diameter plus 2 times the case mouth's thickness. (Usually .010" for most cases. So in the 40 S&W, the Flare Removing measurement should be approx. .420". Or at the tightest, .419". And be sure to "roll the case mouth around," so you don't just measure it in one spot.

Actually (taper) crimping the case mouth into the bullet almost always results in a loss of accuracy. Not removing the flare enough results in malfunctions. Some gunsmith's will recommend "taper crimping" more than what was previously recommended, and that is easy to understand as to why.

If you remove the flare precisely as outlined as above and your pistol (still) has any sort of feedig malfunctions, I can say for sure that crimping the case mouth more is not the solution. Once I learned how to properly set this dimension, I never experienced any malfunctions due to not enough "taper crimp" in over 20+ years of shooting 20-40,000 rounds/year."

be

[Chills1994]

Alrightey then!

My Speer manual is about 10 years old now. It seems like the only thing it says about crimp is that autos get a taper crimp and revolvers get a roll crimp. It also says that semi-auto rifles should have their rounds crimped into the bullet's cannelure.

That's about all it says. Or at least, what I remember of it.

That reloading manual came with my Rock Chucker reloading kit. That was when I used a combination seating AND crimping die. That was w/ RCBS's 3 die pistol sets (size/decap, belling, and then seat/crimping). So it was about a year and half ago when I got a 550 that I learned they actually made separate crimp dies.

Now, my 550 is on it's way to getting completely tweaked.

Why did I even bother buying Dillon's 3 die set?

Soon I'll be runing an EGW/Lee Undersize decapping die, a Redding micrometer adjustable seating die, and then a Lee Factory Crimp Die, with a Uniquetek micrometer screw for the Dillon powder measure.

The only thing Dillon left in the toolheads will be the powder die.

Anyhoo...thanks for your replies.

This is such a great internet forum!

Chills

[jkrispies]

Chills,

The EGW/U-die and Redding Competition Seater Die combo is an AWESOME route to go. If you want to save a little money, though, you might want to hold off on the Lee FCD and try your current crimp die out for awhile first.

In my relatively limited experience, I've found that the only time my rounds won't chamber is when they're seated into the brass cockeyed. For that reason I've gone with Redding, which seats the bullets perfectly straight everytime. Frankly, I'm getting of the mind that an FCD is basically a band-aid that covers a mistake that shouldn't have been made in the first place, and the Redding prevents that mistake from happening.

For the record, if I need to purchase a crimp die for a caliber that I don't already own, I'll most likely opt for the FCD... but I'm not currently bothering to purchase an FCD to replace a crimp die that's already sitting in my toolhead. At least that's been my experience so far, but maybe I'll change my mind in another week.

Just my $.02,

John

[blackdragon]

I don't crimp my ammo unless it won't feed! Never have!

Ivan

[Front Man]

Damn!

I was set in my ways; now I have to rethink everything!

That's what I love about this place!

FM

[JimP]

I use both a caliper - and a case gague to get the tool head set up. Then I use the case gague on every cartridge before I box them up and store them. If they don't drop in and out easily - I check the case and pull the bullets. I also keep a couple of factory shells - usually winchester - with the same type of bullet I'm reloading - and use it as a " QC" finished cartridge. I just keep them in a fishing lure box - and store my case gagues in the same box with the QC rounds. Personally, in the XL 650, I like the Dillon carbide dies - and have thousands of cartridges thru the press in 9mm, .40, .45 , .44, .357 etc