How do I know if I am crimping too tightly?

[thaddeus]

Again, how do I know if I am crimping too tightly or too loosely?

thanks,
thad

[Walt Welch]

Thad; a crimp should be enough so that all traces of the belling of the case mouth by the expander die is removed.

The bullet should be held securely in place by the crimp. The common test for this is to push the loaded cartridge, bullet first, against the loading bench. If the bullet slides deeper, the crimp is insufficient.
An important corrolary of this is that, if shooting a 'small pot' cartridge, such as the 9 x 19, which is VERY sensitive to bullet set back, check the OAL after cycling the loaded round through the action several times. It should not be shortened. Further, at the range, keep the top round in the magazine there for 3 or 4 firings (by ejecting it from the chamber and reloading it in the mag, and putting another cartridge on top to feed into the chamber). This process should not cause the cartridge to shorten either.

Some calibers require a heavy crimp; the .357 Mag and .44 Mag are good examples. A heavy roll crimp improves the precision of bullet pull.

Taper crimp auto pistol cartridges. This is not so much because of the polite fiction that the cartridge headspaces on the case mouth, and a roll crimp will defeat this, but to make the cartridge smooth so it will feed more reliably.

Don't believe me about the case mouth headspacing being a fiction? Well, it is the case. The .45 ACP actually headspaces on the extractor, as that is what is holding the case against the breech face. True, if you drop a .45 ACP round into a bbl. the case mouth will touch the ledge in the chamber.

You see, they have to build in a clearance between the case mouth, as it is really positioned during the firing cycle, and the ledge in the chamber. If they didn't, the slightest bit of junk which got deposited on the ledge would hold the case back, and not let the slide go into battery. Honest.

If you ever reload rifle cartridge cases, I highly recommend the Lee Collet crimper die. This crimps the case from the side, rather from the front, and yields a much more uniform crimp, not at all dependent on case length. I had a lot of trouble with brand new .223 brass varying in length. I could have trimmed all of them, but decided instead to try the Lee Collet die. It worked very very well. Hope this helps, Walt

[bfoster]

Thad... I'd like to expand a bit on a three points which Walt touched on.

1. As you know, in revolver cartridges like the .357 Mag or the .44 Mag the most powerful loads use a large charge of a slow (for a handgun) burning powder. The bullets used for these applications are almost always designed with an appropriately placed cannelure for the heavy roll crimp used- at least if the annunition you want to produce is to conform to SAMMI standards. It is evident on most pressure/time graphs recording the firing of these cartridges that uniformity of powder ignition is improved by the heavy crimp. If you're interested in why, and are willing to suffer a long post, I'd be willing to take a stab at it.

2. In pistol cartridges, a really excessive taper crimp can swage the bullet oversize enough to cause problems. As Walt says, you need enough to hold the bullet in place, and a bit more for the sake of safety. Don't overdo it.

3. Walt is correct about .45 ACP cartridge and chamber dimensions in all except a few very specialized handguns. I might add that if the chamber dimensions are substantially tightened, surprisingly signifigant function/engineering issues arise. For instance, the r&d department of one major manufacturer built a prototype blowback action which had a chamber right at the SAMMI minimum dimensions. It was found that a standard weight slide was about 25% too heavy to function correctly when using SAMMI maximum dimension ammunition. This sort of problem can make a shooter realize what a genius John Browning really was.

regards, Bob

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[The Scandinavian]

Walt: Interesting point about pistol cartridges not truly headspacing on the case mouth. That always had me wondering before! Thanks!

[bear]

Walt, have hear many times to taper crimp auto rounds, I tried this when loading my .45 with 250gr lead bullets, these were loaded fairly warm but can't remember amount of powder (at work now) what would happen is the bullets would work their way out of the case, went to a roll crimp and this stopped, have used a very slight roll crimp on all the .45's that I load now and seems to work just fine, shooting out of a 1911 and a H&K USP.
and load every thing from soft target loads 4.1grs 231 to pretty hot bowling pin loads.
been doing this for over twenty years with the 1911, am I lucky or???? thanks.

[Walt Welch]

bear; I have never had any problems with lead bullets not being held firmly by a taper crimp. While there is nothing wrong with using a roll crimp, be aware that the crimp will then be dependent on case length, so you must maintain a uniform case length.

If I were to hazard a guess as to why your lead bullet is not held firmly by a taper crimp, it would be that the expander plug on the decapping/expanding die is a few thousandths too big in diameter. Walt

[Ed]

Thad- Just want to say amen to Walt's taper crimp advice. I started loading for .45ACP in 1962, and always used the roll crimp that came on the seating dies. With hardball I just set up enough crimp to snug up the case mouth to the bullet and it worked ok, but with 200 or 185 gr lead swc I got too many feed failures on my old pre-war Colt. I thought that was normal for non-throated barrels until I bought a Lee taper crimp die a few years ago. I can honestly say I have not had a single malfunction of any kind with lead bullets of any configuration in either of my guns since I began taper crimping. I know that sounds very unlikely for unmodified 1911's, but I have racked my weak brain and can't think of a single feeding problem since that time. I load 5.5 gr 231 under the 200 gr swc because I get best accuracy with that load, so they get slammed around pretty hard, but I have not had any bullet setbacks as far as I can tell. A buddy has also shot lots of my lead bullet reloads in three of his 1911's with no problems. You won't have to worry about how much crimp to use either, just adjust till you get a fairly firm pull on the press handle at the bottom of the crimping stroke and you're there.

[bear]

Walt, thanks for the info, have a brand new set of dillon dies I can try, the set I'm using now are probably older than both of us, maybe time to retire them. Al

[Dennis Glover]

Thanks guys. This is a subject that I've been dealing with the past few days. Looks like a Lee taper crimp die is in the future for me. I've got a new Kimber that has a real tight chamber and until now crimp or not to crimp was no where close to a question in my mind, but a few miss feeds have sent me searching. Walt thanks for your input I'll place an order in the morning.

[Ray Hawk]

With reference to crimping. Should one crimp a 9mm FMJ or HP? One person told me to take the chamfer tool and give the inside of the mouth of the brass a couple of turns. After the powder has been dropped, seat the bullet. The pressure of the down stroke will push the sides in enough around the lip of the case where you have turned it, that it will hold the bullet in place.

Any suggestions?


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Ray Hawk

[hal becker]

if bullet can be moved into case your not crimping enough,one thing I've learned fast
is all cases have to be same length or some
will be under or over crimped, overcrimped
pushes the neck down into case and ya can't
chamber those rounds, a cheap tool is Lees
case length gauge and shellholder, if cases are too long it wil cut them to size, by hand
and someone posted to me about Midway, they
do have overall case-length gauges for most
pistol cartridges,and a gauge in 4 different sizes that cover 139 popular calibers, I
just printed that from a Midway catalog,

[James K]

The .45 ACP not headspacing on the case mouth but on the extractor. That is a new one on me, and I'll bet it is new to SAAMI also. Since a case held by the extractor may be several hundredths of an inch from the breech or may be right against it, the case mouth and the bullet seating in the barrel leade will be all over the place. I am astonished that you can get good accuracy.

It is easy to crimp .45 cases with lead bullets so they headspace on the case mouth and still have good bullet retention. I have loaded "pin" loads with a 255 grain SWC bullet that were HOT! The crimp always held and the case headspaced on its mouth. (Those loads didn't just knock pins over; the bullets picked up the pins and moved them horizontally off the table.)

[Ray VanderLinden]

Jim,
Walt is right about the .45acp head spacing on the extracor. If you have them all headspacing on the case mouth you had to do a LOT of work to get it there.
If you take any hand full of once fired brass and messure it. You will find that nearly all of the brass is SHORTER than the suggested trim length.
I didn't believe it either. But it's true.

[This message has been edited by Raymond VanDerLinden (edited March 23, 1999).]

[James K]

Raymond and Walt,

Let's try this again. To be actually held back by the extractor, the case would have to be extremely short, as the M1911/A1 has a large gap (about 2mm) between the extractor hook and the breech face. (Go look!) In addition, when a round is loaded from the magazine, there is no real force except inertia that would force the cartridge out against the hook. Of course if the hook did hold the cartridge, the firing pin would still reach the primer; it jumps out a 1/2 inch or more when struck by the hammer, but that is not the way things are supposed to work.

Even if somehow the case is held back by the extractor, it will come back against the breech pretty fast after firing. I suspect that no matter what you say, your cases are really coming to rest against the chamber shoulder. If there is a roll type crimp, the crimp will be part way into the barrel leade. That raises pressures, as both the case mouth and the bullet are trying to fit into a space meant only for the bullet.

Also, cases held by the extractor or allowed to go too far into the chamber may have flattened primers. Here's why. The firing pin drives the cartridge to the limit of the extractor hook, the cartridge fires, the primer backs out into the excess headspace and expands under the pressure, then the case backs out over the primer, flattening it. Looks like excessive pressure. How do I know all this? Easy. I tried it all before some of you folks were even a gleam.

Suggestions:

1. Take the gun down and drop one of your reloads into the chamber. If the distance between the case head and the end of the barrel is less than the distance between the breech face and the extractor hook, the case is being stopped by the chamber shoulder, not by the extractor.

2. If you have an old worn out barrel, cut it in half length wise and see what your loads actually look like in the chamber.

Raymond,

Sure cartridge dimensions vary. That is why good reloaders separate brass by length and adjust the crimp accordingly.

[Ed]

Jim - You sound as though you have been stuffing .45's for quite a few years. I started reloading in 1960, but didn't get a .45 until '62.

I also tend to think the case headspaces on the chamber shoulder. I use a taper crimp die, and I can drop a loaded case into a disassembled barrel and it stops with a clunk against the shoulder. In my guns there is a fairly large gap between the hook and the breech block face. Seems to me the case would stretch a lot if it headspaced on that hook and the case gripped the chamber wall under pressure. On second thought, I 'm not sure there's enough pressure there for the case to grip the chamber wall like in a centerfire rifle, so my whole theory may be wrong. Offhand, I can't think of any way to prove it one way or the other. I don't suppose it really matters as long as you get decent accuracy and reliable functioning, which I do.

The taper crimp makes a big difference in functional reliability in the old Colt I have. The newer 1911-A1 was pretty good anyway on that point, so I don't see much difference with it. Before I got the taper crimp die I couldn't get a tight enough crimp to keep bullets from creeping under recoil in a mod.1950 Smith .45ACP revolver unless I seated them out far enough to roll a crimp into the top lube groove. Same thing happened with .45ACP bullets (no crimp groove) in .45 Long Colt cases for a Ruger SA. Now I can seat the bullets in properly and they don't move. For me, taper crimping is well worth the little extra time and trouble.

[Bottom Gun]

In addition to recoil, the type of powder used is also very important when determining how much crimp to use. Some years ago, I tried some Hogden H110 powder in my .44 mag. I didn’t use a heavy roll crimp and to my surprise, several rounds did not ignite and the primers pushed the slugs into the forcing cone, disabling the weapon.
Not wishing to overwork the brass by heavy roll crimping, I then tried a medium roll crimp with the same results. . . . .slugs in the forcing cone.
Turns out this particular powder has a coating on it which is pressure dependent and requires a VERY HEAVY crimp for reliable ignition.
Of course heavy crimping will shorten the working life of your brass so I have since gone back to using Unique and back to using a medium crimp to prevent the slugs from walking out under recoil.

[Rew]

Well, I'll throw in my .02 worth. if you look at a drawing of the .45ACP case the case mouth is .473"/12.01mm while the case just in front of the grove is .476"/12.09mm making the .45ACP a very slighty tapered case. In a match chamber you are putting this tapered case into a tapered chamber. I think Mr. Browning intended the case to headspace on one or more of the three. Mouth, extractor, and taper. Now I no longer own an Auto in .45ACP but I trim my cases every 3 loads for my S&W 625 and have never had a problem with headspace with or with out the clips.

Rew

[Rew]

BTW I forgot to say I use a slight roll crimp on both the 9mm and the .45ACP with lead bullets and since I don't make jacketed bullet's, Yet, lead is all I shoot.