Question about a bullet

[Scott]

What is the green gel like line that goes around the bullet in this picture?

Does it effect the way that I'm crimping? Is it only for one type of crimp (roll vs. tapered) and shouldn't be used for the other? And finally, what is the difference between a plated bullet and cast bullet such as this? I understand that one has a jacket, but what exactly is the significance?

I've been using the Xtreme copper plated bullets and have had no problems with them except for an occasional mis-crimp(?) where the jacket peels back and bunches up around the brass lip. But I was looking for something that I didn't have to worry about the jacket bunching up and was cheaper.

TIA.

[pa_guns]

Hi

Another name for the gunk is lube. As in bullet lube. A supposed side effect of using the stuff is to reduce the ammount of lead that gets deposited on the barrel when the round is fired.

The crimp (or lack of) is mainly a function of the cartridge you are loading rather than the bullet. What are you loading?

Bob

[Scott]

.45 ACP and 9mm. The 9mm is both for pistol and for a carbine rifle.

[pa_guns]

Hi

Both the 9mm and the 45 acp headspace on the case mouth. A crimp keeps the case mouth from properly contacting the chamber. You should not put a crimp on either one. You can get away with it on most 45's but it's a definate no-no on a 9mm.

Bob

[Hoser]

You should not put a crimp on either one. You can get away with it on most 45's but it's a definate no-no on a 9mm.

High pressure rounds like the 40 and 9x19 absolutely, 100%, without a doubt require a crimp. When an uncrimped round hits the feed ramp, the bullet can actually get pushed back in the case. This will cause your pressures will skyrocket causing something along the lines of a Kb at the worst and popped primers or blown cases.

When reloading, you have bell the case (slightly more bell for lead bullets) to allow a bullet to go in, you also have to get rid of that bell so it will feed. You want to crimp enough to hold the bullet in place but no so much to hurt accuracy.

Semi-auto rounds get taper crimped and revolver rounds normally get a roll crimp. Two different dies.

[Scott]

All my dies are taper crimp dies and my process is like Tom Freeman explains - bell the mouth slightly to seat the bullet and taper crimp just enough to get rid of the bell. Whether I'm doing too much taper crimp, I have no idea as I haven't really tested the accuracy of he ammo vs. less crimp.

I don't know what the term head space means. Can someone explain more?

Thanks.

[Hoser]

I don't know what the term head space means. Can someone explain more? Depth of a chamber.

[pa_guns]

I don't know what the term head space means. Can someone explain more?


Hi

When you put a round in the chamber you want it to only go in just so far. Some part of the bullet case has to hit the chamber somewhere to stop it moving forward. The distance from that point back to the primer end of the cartridge determines how far the firing pin is going to have to go before it hits the primer. On some cartridges the point that hits is way far back on the cartridge (the rim), on others it’s way forward (the case mouth).

You want the cartridge to fit in the chamber "loose enough" that the bolt closes. You also want the cartridge to fit in the chamber "tight enough" that the brass does not stretch to much when the cartridge goes boom.

On a cartridge like the 357 you force the open end of the brass down into a crimp grove (the cannelure) in the bullet (a full crimp). The cartridge headspaces on the rim so this works fine. If you look at a .357 you can see the brass "bending" into the bullet on a loaded round.

If you put a full crimp on a 45acp the same way you do on a 357 you are going to have trouble. The "mouth" of the round should be taken down below 0.471, but probably not below 0.4685 for most pistols. If you look at the 45 acp cartridge the walls of the brass are straight. If you do not get enough bullet tension with the mouth at 0.468 then the brass probably needs to be tossed or your bullets are under sized.

Bob