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STI .40 Cal With Tight Chamber......


MikieM

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I just got in a new STI Edge in .40 S&W. I loaded about 95 rounds using Winchester (sized, and roll-sized) brass with 5 grains of WSF under a PD 180 grain JHP. Primers are CCI.

Went to the range to give it a try, but before I did I pulled the barrel and plunked a few rounds. They didn't plunk. I had to push them in with my finger to get them to chamber.

Since the S&W's are straight wall cases I tried plunking them backwards (case head first) and they went in fine. Painting the bullet with magic marker showed no marks from the rifling.

The bullets measure .399 on average and are seated to 1.180 inches.

I went to the range anyway and shot the gun. About 20 percent of the 95 rounds wouldn't allow the slide to close all the way, but I could close it by hand. Other than that, the gun would feed and eject the ammo just fine, and accuracy was good.

Has anyone had a similar problem? 

Will the gun shoot in?

Will I blow myself up?

Any help would be greatly appreciated.

 

P.S. This is my first time ever with .40 caliber.

Edited by MikieM
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The first thing I'd do is visually check the chamber with a light to see if there's some gunk/fouling/powder residue/etc., that's keeping it from going into battery.  Then I'd take a nylon bore brush, chuck it into a cordless drill and clean the chamber out. 

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19 minutes ago, MikieM said:

 

.423 inches.

 

I know a .40 s&w chamber is supposed to be .424" (i think, something like that), but I would try tightening your crimp on a couple of rounds and see what that does.  I think my crimp measures .421" if I remember right and think most people are generally in that area.  

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I know a few guys that sent their STI 40 guns to have the chambers opened up a tad because they were so tight.  I had an edge myself but I was lucky and didnt have a problem.

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18 minutes ago, Edge40 said:

I know a few guys that sent their STI 40 guns to have the chambers opened up a tad because they were so tight.  I had an edge myself but I was lucky and didnt have a problem.

 

Looks like that's what I'm going to have to do. 

Sized cases will plunk, but loaded rounds won't. And that's with seating depths all the way down to 1.125 inches.

It's always something, isn't it? 

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A crimp of 0.424 is still a little bit of Bell. Zero crimp would be 0.420 so why not at least use that? There is no reason to still have some bell on the case mouth on loaded ammo. If you are not using any crimp to retain the bullet in the case I would suggest you watch out for bullet setback as it chambers. This is easy to test by measuring the OAL of the rounds before shooting. Then fire a few rounds at a rapid pace and then extract the live round that is chambered and recheck the OAL. If the OAL is dramatically reduced then you are going to need some crimp to minimize that.

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Cha-Lee is right that the crimp should be .420 rather than .424 and that there should not be any bell on the case mouth after crimping.  However, the point about crimp preventing setback is not correct.  It doesn't do that, and isn't supposed to (on a semi-auto cartridge).  To prevent setback you need to have a sufficient interference fit between the case and bullet and that is achieved by using a correctly sized die.  If you crimp to the point that it prevents setback on a case that isn't sized sufficiently, chances are you're going to see a drop in accuracy, or even end up with tumbling bullets.

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1 hour ago, MikieM said:

Fixed it! 

It was the crimp after all, or at least not enough of it. .424 seems to be the magic number.

Darkvibe win todays prize, but thanks to everyone. :bow:

 

You can buy me a glass of bourbon if we ever shoot a match together ;)

 

Glad you got it figured out.

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41 minutes ago, ltdmstr said:

Cha-Lee is right that the crimp should be .420 rather than .424 and that there should not be any bell on the case mouth after crimping.  However, the point about crimp preventing setback is not correct.  It doesn't do that, and isn't supposed to (on a semi-auto cartridge).  To prevent setback you need to have a sufficient interference fit between the case and bullet and that is achieved by using a correctly sized die.  If you crimp to the point that it prevents setback on a case that isn't sized sufficiently, chances are you're going to see a drop in accuracy, or even end up with tumbling bullets.

 

And eventually blow up your gun from setback because crimp isn't going to be sufficient in one round eventually and one is all it takes.

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I never measured my crimp. I crimp it until it plunks in the chamber and push it into the side of bench to make sure no setback. Measure coal before and after. Setback in a 40 with blow up the gun.  Don't ask how I found out about 18 years ago, but I had to replace a glock.

 

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Measuring .421 at the case mouth, and .421 at the case head, just in front of the extractor groove. All rounds plunk in and out of the barrel.

Am going to the range in the morning to try it out. If I don't report in I've had a setback. (I couldn't resist.)  :lol:

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I just got back from the Emergency Room......I mean range, and am happy to report that every thing went fine. Out of 100 rounds there was only one failure of the slide to close.

From this point on I think I just need to get more rounds through the gun. It looks like the crimp was indeed the culprit.

Thanks to everyone for your valued advice.

Mike

Edited by MikieM
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your going to have different length brass.  You will need a case gauge.  You will end up with more crimp then you think you need.  when setting a new crimp die i crimp until it plunks then go a quarter turn more.  If I have trouble gauging after that I add more crimp.  I recently moved to the redding micro crimp so I dont have to mess with stupid lock rings and guessing on adjustments.  If you have roll sized brass the other problems you will run into are not enough crimp and not seating the bullet in straight.  Getting the bullet sitting straight before seating is an important step.  

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I have been using the Lee bulge buster to remove those bulges and then case gauge them. Those that dont fit in the case gauge, do not use at all and just take them apart.

 

Just my two cents

 

And yes, sometimes even if they fit in the barrel when the ammo is reverse side put in but does not fit when projectile head is first.

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I have been using the Lee bulge buster to remove those bulges and then case gauge them. Those that dont fit in the case gauge, do not use at all and just take them apart.
 
Just my two cents
 
And yes, sometimes even if they fit in the barrel when the ammo is reverse side put in but does not fit when projectile head is first.

And/or run them through the bulge buster again once loaded. Using the Lee FCD helps a ton aswell
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I have just purchased a Lee FCD. Will be using it next week.

I've been using my barrel to plunk test the ammo, but will be getting a Shockbottle case gauge for match ammo, soon.

My brass will plunk both ways. Head first and case mouth first. I buy it roll-sized.  

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I have just purchased a Lee FCD. Will be using it next week.
I've been using my barrel to plunk test the ammo, but will be getting a Shockbottle case gauge for match ammo, soon.
My brass will plunk both ways. Head first and case mouth first. I buy it roll-sized.  

Roll sized is the only way to go with 40 brass
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  • 1 month later...

Bought an Edge as a back up in April for my CK (and for Steel and 2X year IDPA) and the chamber is ridiculously tight. Running a U die, bulge buster, FCD, nothing works with this thing. Can run plated bullets crimped properly but, Bayou's run .401-.402 and they will not run at all. Any bullet over .400 is an issue with this barrel. Sending barrel out to open the chamber up, this chamber is stupid tight for its purpose.

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