Over Crimped?

[m00se]

While loading 40 S&W tonight I measured my cases after flaring and then after crimping. I'm flaring them to about .425 - just enough to allow the bullet to seat. But my crimp was only bringing them down to .424 or .424, so I tightened it a little. I ended up with crimps at .418-.421. Then I checked the SAAMI spec (should have done that first) and noticed that the case mouth should be .423. But the spec also says the case can be -.008. If I'm doing the math right, I'm still in spec. There are no signs to trauma to the bullet, and the case mouth is not buried in the bullet. The crimp was done with a Lee FCD.

Since this is the second batch, I took the load up by .2gr to 6.1gr of CFE pistol with a 180gr plated bullet. I'm still .4gr below the max charge, and the max produces a little under 33,000 psi at 1.125 OAL. Mine are 1.126-1.129. Any thoughts on whether these bullets are safe to shoot?

 

[Jim Puke]

Based on the figures you provided, these rounds should be safe. If in doubt, as a reloader, always follow your gut feeling...it is there for a reason...to keep you safe.

Also, remember, with autoloaders, enough taper crimp to remove the flare is all the crimp that is really needed.

 

[Cheesewhiz]

I don't reload .40 SW but I have used headspace gauges and although not perfect they can help you get to where you need to go.

http://www.amazon.com/Lyman-Reloading-Pistol-Cartridge-Gauge/dp/B005I0IUPY/ref=sr_1_fkmr2_1?ie=UTF8&qid=1411997861&sr=8-1-fkmr2&keywords=lyman+headspace+gauge+.40

Some semi-auto barrels have a strange leade (Glock is one) and if the round doesn't headspace correctly that leade can act as a clamp. Even if you have a safe load and length, the leade will clamp into the case further down, not allowing the case mouth to expand and release the bullet as it should. This could cause excessive pressure and a case blow out may occur. This seems to be a fairly common thing with Glocks and .40 SW reloads, it is not an unsupported chamber issue but a round that went too far into chamber and turned the case into a balloon.

This is a video posted by a guy that finally finds the real reason his .40 Glock blew up, he had posted several videos blaming the barrel and it's design and many other things but in this one he gets it right, well sort of. He tosses out a few bad words, so be warned.

http://www.youtube.com/watch?v=u5oa3D4SDzs

 

[m00se]

Thanks for the link, Cheesewhiz. My over-crimp isn't as severe as the diagram in the video, but I'm not sure if they will headspace correctly. I may chalk these up as a "learning mistake". I re-measured OAL and discovered that they are longer, by as much as .004 or .005 (1.130 instead of 1.125 or 1.126) after the crimp than they were after being seated. Now I have to wonder - did the crimp pull the bullet out slightly, or did the bullet stretch? And if it stretched, did it just stretch outward or did it also stretch into the case, which would affect case volume?

 

[powder smoke]

Cheese, Thanks that vid really helped me out. Going to load my first acps shortly timing is good for me
I read and some have advised me but seeing it helps, never loaded rimless cases before. ps

 

[Rick Courtright]

This is a video posted by a guy that finally finds the real reason his .40 Glock blew up, he had posted several videos blaming the barrel and it's design and many other things but in this one he gets it right, well sort of.

Hi,

Interesting video--thanks, Cheese!

One thing the gentleman mentions down in the comments section is that his case itself may well have been overlength. That could certainly contribute to a crimping problem over and above any other causes.

So one of the messages I got out of that is the reminder to always measure your auto cases, after sizing, before priming or taking any other steps. A simple "go-no go" gauge is adequate--you don't need to take the calipers to each and every one! I only load one auto caliber, the 9mm, and it seems my cases "shrink", a phenomenon I've seen discussed elsewhere, but with range brass, I have found some that are overlength. It's rare for me, but, as the gentleman showed us, it only takes one to ruin your day!

Rick C

 

[Cheesewhiz]

This is a video posted by a guy that finally finds the real reason his .40 Glock blew up, he had posted several videos blaming the barrel and it's design and many other things but in this one he gets it right, well sort of.

Hi,

Interesting video--thanks, Cheese!

One thing the gentleman mentions down in the comments section is that his case itself may well have been overlength. That could certainly contribute to a crimping problem over and above any other causes.

So one of the messages I got out of that is the reminder to always measure your auto cases, after sizing, before priming or taking any other steps. A simple "go-no go" gauge is adequate--you don't need to take the calipers to each and every one! I only load one auto caliber, the 9mm, and it seems my cases "shrink", a phenomenon I've seen discussed elsewhere, but with range brass, I have found some that are overlength. It's rare for me, but, as the gentleman showed us, it only takes one to ruin your day!

Rick C

Rick - Take a look down this page to powder smoke's thread "New to me .45."

I made a post in which I mention a discussion I had with a Winchester Ammunition rep at the NRA Annual
back in 2011. My specific question was in regard to semi-auto cases (I was concerned solely with .45acp)
shrinking. This was something I noticed due to my extremely anal nature when reloading.

I measure cases after full length sizing. Sure enough, some of them are shorter than they were for the
previous loading. The Winchester man said that this happens frequently when cases are loaded to full
power or a bit hotter. I've yet to load an honest-to-goodness "+P" load for my .45acp, but I do load full
power loads. Not every case will shrink, but enough do to get your notice if you are indeed paying attention.

My guess is that the opposite is probably also true: guys who load nice, soft shooting loads (Bullseye shooters)
probably have no case stretching to speak of. - DixieBoy

I have a .010" rule with my 9mm cases. I load so much and at higher levels that I batch test. When samples taken from a certain batch of cases reach a shrinking length after sizing of more than .010", they all get pitched.

 

[Jimbo357mag]

Thanks for the link, Cheesewhiz. My over-crimp isn't as severe as the diagram in the video, but I'm not sure if they will headspace correctly. I may chalk these up as a "learning mistake". I re-measured OAL and discovered that they are longer, by as much as .004 or .005 (1.130 instead of 1.125 or 1.126) after the crimp than they were after being seated. Now I have to wonder - did the crimp pull the bullet out slightly, or did the bullet stretch? And if it stretched, did it just stretch outward or did it also stretch into the case, which would affect case volume?

When you crimp a bullet the OAL of the cartridge is going to grow a little. I think it would be a good idea for you to chamber those rounds by hand and see if they seat on the case mouth. That is the important thing. I've heard that called a 'plunk test' because of the sound the cartridge makes when it is dropped into the chamber.

 

[m00se]

When you crimp a bullet the OAL of the cartridge is going to grow a little. I think it would be a good idea for you to chamber those rounds by hand and see if they seat on the case mouth. That is the important thing. I've heard that called a 'plunk test' because of the sound the cartridge makes when it is dropped into the chamber.

I was thinking of doing exactly that. If they chamber correctly I may go ahead and shoot them.

 

[Cheesewhiz]

A plunk test is a good way to find the maximum possible overall length of a reloaded round with a given bullet in a given barrel of the pistol you are reloading for. A plunk test in a barrel's chamber is a lousy finished round/case gauge.

 

[m00se]

A plunk test is a good way to find the maximum possible overall length of a reloaded round with a given bullet in a given barrel of the pistol you are reloading for. A plunk test in a barrel's chamber is a lousy finished round/case gauge.

I agree. But in this case, I also disagree. In the video you that you linked, the problem was that the mouth of the round went past the chamber and in to the leade. Since that is one of the things I am concerned about with my over crimped rounds, the plunk test is a valid way to check to see if that is happening. And it isn't happening - all 12 rounds chamber correctly and cannot be forced in to the leade. I didn't let the slide slam them home, but I did press hard on every round, and then I tried to "wiggle" them past the chamber. I may try letting the action chamber each one. If the slide pushes the case past the chamber I would expect the slide to be harder than normal to operate, and there should be evidence on the case mouth.

I'm still not sure I'm going to fire these rounds, but this discussion is helping me learn more about reloading.

 

[Rick Courtright]

I agree. But in this case, I also disagree. In the video you that you linked, the problem was that the mouth of the round went past the chamber and in to the leade.

Hi,

mOOse, don't worry, be happy: cut loose with a couple of bucks and eliminate the doubt!

Gauges of this type are popular and handy to check your sized cases for maximum length. You can do the same job with your calipers, but these make the job quicker. The first one is just for pistol/revolver brass, the second one also handles rifle brass.:

http://www.midwayusa.com/product/150213/lyman-e-zee-case-gauge-pistol-and-revolver?cm_vc=ProductFinding

http://www.midwayusa.com/product/559802/lyman-e-zee-case-length-gage-ii?cm_vc=subv1559802

Once you've got the round loaded, this type gauge should help put your mind to rest:

http://www.midwayusa.com/product/276502/le-wilson-max-cartridge-gage-40-s-and-w?cm_vc=ProductFinding

Such gauges are made for most every cartridge we're likely to run into on a daily basis, and should probably become part of your "specialty" tool collection sooner than later when dealing with a "known to be persnickety" round like the .40 S&W.

And I'd guess you've already got an "eraser" for any questionable rounds you find? While this one's from RCBS, you'll find many similar versions:

http://www.midwayusa.com/product/685703/rcbs-powr-pull-impact-bullet-puller-kit?cm_vc=ProductFinding

Rick C

 

[Jimbo357mag]

I agree. But in this case, I also disagree. In the video you that you linked, the problem was that the mouth of the round went past the chamber and in to the leade.

Hi,

mOOse, don't worry, be happy: cut loose with a couple of bucks and eliminate the doubt!

Gauges of this type are popular and handy to check your sized cases for maximum length. You can do the same job with your calipers, but these make the job quicker. The first one is just for pistol/revolver brass, the second one also handles rifle brass.:

http://www.midwayusa.com/product/150213/lyman-e-zee-case-gauge-pistol-and-revolver?cm_vc=ProductFinding

http://www.midwayusa.com/product/559802/lyman-e-zee-case-length-gage-ii?cm_vc=subv1559802

Once you've got the round loaded, this type gauge should help put your mind to rest:

http://www.midwayusa.com/product/276502/le-wilson-max-cartridge-gage-40-s-and-w?cm_vc=ProductFinding

Such gauges are made for most every cartridge we're likely to run into on a daily basis, and should probably become part of your "specialty" tool collection sooner than later when dealing with a "known to be persnickety" round like the .40 S&W.

And I'd guess you've already got an "eraser" for any questionable rounds you find? While this one's from RCBS, you'll find many similar versions:

http://www.midwayusa.com/product/685703/rcbs-powr-pull-impact-bullet-puller-kit?cm_vc=ProductFinding

Rick C

Those are great but none of them address the problem of over-crimping a semi-auto round to the point where it slips past the lip of the chamber. (see edit) What would be needed, and you could make it yourself, would be a piece of steel or hard plastic with the correct size hole drilled into it. You could put the bullet into the hole but the case mouth would not pass through if correct. If the case was over-crimped the case mouth would slip into the hole opening just like in the chamber.

edit: Actually the L.E. Wilson Max Cartridge Gage 40 S&W http://www.midwayusa.com/product/276502/ does address the crimping issue. Too much crimp and the finished round does not sit level.

 

[Rick Courtright]

Those are great but none of them address the problem of over-crimping a semi-auto round to the point where it slips past the lip of the chamber.

Hi,

Agreed to a point, Jimbo: this is one of those cases where it's not the tool but the technician that makes or breaks the process...

As another poster mentioned, the amount of crimp required for a rimless pistol case is usually "just enough" to remove the bell. If there's not enough crimp, the round shouldn't fit into the gauge, so one simply adds "a touch" of crimp as required until it does slip in properly, and the case should stop in the gauge to indicate if it's overlength. There's a shoulder in there for that purpose which I believe is the same thing you're suggesting we "need."

The way I understood the gentleman's explanation of his Glock's kaboom, it was the COMBO of overcrimping AND overlength case that created the problem. Bad QC on his part? Had the case been of proper length but overcrimped, it could have expanded normally in the chamber on firing. No worries. But it appears his was confined by the leade, so it couldn't expand normally. Big worries! Now, Wilson claims their gauges meet SAAMI specs, so if your ammo passes with them, it should work in any SAAMI spec chamber. Despite any particular Glock idiosyncracies, their chamber still meets those specs, doesn't it? If I misunderstood, someone can set me straight...

Wilson has a quick video that may help 'splain their gauge's use better: http://www.youtube.com/watch?v=u8Xr1hYCDnM

As with many procedures, the operator should be able to easily develop a "feel" for what's right, what's not, when using the gauge. Adding a little "art" to the "science?" Of course, a ham handed operator is not the tool's fault!

Rick C

 

[m00se]

I think I misunderstood Cheesewhiz's original point about the case gauge. None of my over-crimped rounds are longer than 1.135 OAL. Case length on each round is .845-.846. Saami spec for .40S&W case diameter is .4231, -.008. Unless I'm mistaken, that allows a case diameter of .415 to .423. Even over-crimped, my cases are still at least .419 at the case mouth. However, I'm unclear as to whether the -.008 spec applies to the case mouth as well as the rest of the case. In my situation, a case gauge would not have revealed anything I didn't already know from measuring with my caliper. However, if I had more than a dozen rounds to measure, the gauge would be a lot faster. I'll probably pick one of for future use

And I guess this takes me full-circle back to my original question - will my crimp cause a dangerous increase in pressure? The rounds are to spec, have a relatively light charge, and appear to chamber correctly (which in this case means the case does not slip in to the leade). Unfortunately, I think the correct answer to my question is still "maybe". I'm not willing to risk my fingers and gun on a "maybe".

Jimbo - I don't have an "eraser" yet. Yay... something else to spend money on

 

[Chief_10Beers]

I don't reload .40 SW but I have used headspace gauges and although not perfect they can help you get to where you need to go.

http://www.amazon.com/Lyman-Reloading-Pistol-Cartridge-Gauge/dp/B005I0IUPY/ref=sr_1_fkmr2_1?ie=UTF8&qid=1411997861&sr=8-1-fkmr2&keywords=lyman+headspace+gauge+.40

Some semi-auto barrels have a strange leade (Glock is one) and if the round doesn't headspace correctly that leade can act as a clamp. Even if you have a safe load and length, the leade will clamp into the case further down, not allowing the case mouth to expand and release the bullet as it should. This could cause excessive pressure and a case blow out may occur. This seems to be a fairly common thing with Glocks and .40 SW reloads, it is not an unsupported chamber issue but a round that went too far into chamber and turned the case into a balloon.

This is a video posted by a guy that finally finds the real reason his .40 Glock blew up, he had posted several videos blaming the barrel and it's design and many other things but in this one he gets it right, well sort of. He tosses out a few bad words, so be warned.

http://www.youtube.com/watch?v=u5oa3D4SDzs

Excellent! A must watch for anyone who loads for semi Auto, Rimless Cartridges ........................................

PS: This should be made a sticky..........................

 

[m00se]

There is a very simple procedure for determining how much taper crimp should be applied and it's defined slightly differently in different load manuals, or not listed. That is to find the case-wall thickness within a couple of millimeters of the case mouth, double it, add the diameter for the bullet you're actually using then subtract the amount of taper crimp you want to apply. The typical range is .002 - .003". You really need to determine what you need. The paramount concern is eliminating set-back. That is mostly the function of a properly sized expander that should be .398" diameter or slightly smaller. That ensures good case-neck tension, but a good taper crimp helps and aids functioning by eliminating the square edge at the case-mouth on a loaded round.

That's how I got in to this mess I measured my bullets at .401, then measured case thickness at .01. The only problem was that when I read .01 my brain registered .001, so I kept tightening the crimp looking for a finished diameter of .403 at the case mouth. Something didn't seem right when adding more crimp wasn't making much of a change to the case diameter, so I stopped.

Further measurements indicate that the case mouth may be as small as .415 - it's hard to measure the tip of the case with the caliper.

My first batch was crimped to .424 and I had no issues with set back or feeding, and my rounds did not change length at all when crimped. Since the most common answer I see *anywhere* on the net and in reloading manuals is to crimp to remove the bell and no more, I think I'm going to re-adjust the FCD to crimp to .423. If they pass the set-back test then "zero" crimp is fine with me.

So definitely "plunk" test, but also "push" test by pressing the nose of the bullet into the wooden top of your reloading bench. With proper case-neck tension and a good taper crimp, the bullet will not setback. If it does even by a thousandth or 2 apply slighty more taper crimp and also make sure your expander is at least .002" smaller in dia. than the jacketed bullet you're using.

I have a reloading bench? Someday I will have a bench. For now I use a Lee hand press.

 

[m00se]

Accuracy does indeed matter. I'm probably overly cautious with my charge weights and OAL - still trying to figure out how a round occasionally comes out .001 short. It was a mathematical error and not carelessness that caused me to over-crimp, but I'm sure some would argue that the mathematical error was careless as well.

I'm only flaring to .424 or .425 - just enough that the bullet doesn't fall over when I set it on the case mouth. Some of them sit very slightly "crooked" but that doesn't seem to affect the seating. The case is not visibly flared, but I can feel it with my finger and I can see a tiny black band between bullet and case when I look straight down on the seated bullet. Crimping to .423 removes the tactile "lip" and the black band.

My first batch was crimped to .423 and set-back was not an issue. I'll check this batch for set-back as well and if they pass the test I'm sticking with .423. I measured my PDX-1 factory ammo - .423 at the case mouth.