My 10mm GP 100 Experience...

[44Blam]

I love this gun. Very accurate, the trigger is very smooth and I just like the feel of it.

Now here is the "yeah but":
Some folks will have you belive that you can shoot 40 S&W out of it... Here is my experience:

I shot 72 rounds of 10mm that were 188 grain boolits going about 1275 fps. They went BANG. And every single one of them went bang...

Introduce the 40s... I've got a nice load I shoot in my glocs that is a 180 grain boolit going about 900 fps (in my glock). It functions flawlessly in the glock.

Load it in my revolver with Ranch moon clips and out of about 75 rounds shot, I got 2 pierced primers and a lot of gunk in gun...



One of the things I think is wrong is that 10mm is a large pistol primer and 40 s&w is a small pistol primer... My glock sets these small pistol rounds properly, but I think the big firing pin doesn't...

[Traffer]

Is there much difference in power of a 10 mm being shot in a revolver compared to a semi auto?

[Todd N.]

Is there much difference in power of a 10 mm being shot in a revolver compared to a semi auto?

In an apples-to-apples comparison, any ammo will be slightly slower in a revolver when compared to a semi-auto with the same barrel length. This is due to pressure losses at the barrel-cylinder gap. However, not all barrels are the same. In reality, the 15-25 FPS velocity loss you MAY experience in a revolver is negligible and you would most likely never notice it.

[reddog81]

Is there much difference in power of a 10 mm being shot in a revolver compared to a semi auto?

The velocity should be about the same as Todd N mentions, however there is a notable difference in recoil. I find that an N frame revolver generally has more kick than the same round in a 1911. The slide moving back and forth kind of soaks up the recoil for full strength loads. However with real light loads I can shoot the revolver faster because it doesn't have the recoil spring moving the slide forward and causing the barrel of the gun to dip.

I have no idea what'd cause the pierced primers. I know shooting 40 S&W in the 10 can cause issues because there are slight variations in the shape of the extractor groove, but I'm not sure how that'd cause a pierced primer.

[Todd N.]

the 40s... I've got a nice load I shoot in my glocs that is a 180 grain boolit going about 900 fps (in my glock). It functions flawlessly in the glock.

Load it in my revolver with Ranch moon clips and out of about 75 rounds shot, I got 2 pierced primers and a lot of gunk in gun...

It's hard to say without having your gun in my hands to examine it closely, but I have a hunch you are having headspace issues with the moon clips you are using. I only shoot 10mm in all of my 10mm guns so I have no experience with these symptoms. However, pierced primers and misfires are a good indicator of excess headspace. I use the TK Custom moon clips in my Super Redhawk and the factory S&W moons in my 1st Gen 610- no problems at all.

On the other hand, my SRH has been rechambered to 10mm Magnum. I still shoot some standard 10mm brass in it occasionally, so that is similar to your .40 S&W usage. Regardless of that, I have no function issues with either cartridge.

There is a thread that started here in the last few weeks about moon clips. I think people were mentioning how varying thickness of different brands of moon clips made a considerable difference in function and reliability. You could also start a very specific thread about this in the Gunsmithing subforum.

[Ramjet-SS]

What I found with my 10mm GP100 is it really loves lighter bullets and the Gun is much easier to control and get quick shots on target and staying on target.

[Petrol & Powder]

As mentioned, some of the problems are head space issues. Varying thickness of the moonclip, the dimensions of the extractor groove on the cartridge casing, the headspace of the revolver (the distance between the rear face of the cylinder to the recoil shield), will all have an effect.

The 10mm casings will headspace on the case mouth and fire without a moonclip but they need the moonclip for the extractor to work.
The shorter 40 S&W casings need the moonclip for headspace and extraction.

[contender1]

I have been using .40 S&W ammo in my MC 10mm a lot. I've not had any examples of pierced primers,, but I have had some light strikes. I also use Ranch moons.
My load is a 180 grn Xtreme plated bullet loaded for USPSA major PF, at 170-171. I use Unique powder, and WW primers.

I may try 10mm brass to see if that cures any light strike issues.

[RJM52]

ZERO problems with the more expensive TK Custom thick clips...

Had at least 50% failure to fire with the OEM clips when using 40 S&W but with the TK clips it hummmms right along....0 misfires...

I've been meaning to get some of the Ranch Products clips as several owners have said they have had no problems when using the .40s with them...but now I wonder... They aren't much money so I'll probably try some one day...

Contender...the 10mm brass headspaces on the case mouth in the chamber so you don't even need clips...they are just for ease of ejection unless you crimp them so hard that they fall off the headspace shelf...

Bob

[RJM52]

Double post...

[contender1]

I use my MC in 10mm with the 40 S&W ammo in USPSA competition. I need the moons for speed.

[44Blam]

I was using the Ranch clips...

Here is a couple pieces of brass - the dent in the primer is very large compared to the size of the WSP primer.


I think I was getting poor ignition (hence the gunk) and it was getting in the extractor and causing the whole cylinder to bind up.

Also, my 40s were printing high - I thought this was odd.

[bluelund79]

I have tried the S&W 40cal moon clips with the same disappointing success as the factory moon clips. 10mm, no issues. I love my GP100, enough that it comes with me into the mountains in a chest rig. Guess my 40cal ammo will get shot out of my old XD, and I’ll just make some practice 10mm that can shoot with my mountain loads. If I could figure it out with 44mag, I can do it with 10mm.

[Todd N.]

I was using the Ranch clips...

Here is a couple pieces of brass - the dent in the primer is very large compared to the size of the WSP primer.


I think I was getting poor ignition (hence the gunk) and it was getting in the extractor and causing the whole cylinder to bind up.

Also, my 40s were printing high - I thought this was odd.

There is nothing wrong with the primer appearance on your .40 S&W brass. You have a firearm that was built to fire a cartridge with a Large Pistol Primer. You are now firing a Cartridge with a Small Pistol Primer in that gun. The tip of the firing pin will obliterate more of the surface of the the small primer than the large one. I can't tell from the picture, but are these the 2 cases that you said have pierced primers? Again, pierced primers are often an indicator of excessive headspace. Taken in combination with your claims of misfires, and many statements from other people trying the same gun/cartridge pairing that you are (this is not the only gun forum where the moon clip thickness is being discussed) with the same issues, the cause AND the solution become quite easy to work out-

Either replace your moon clips with the TK Custom clips, or shoot 10mm ammo in your 10mm firearm. The 10mm/.40 S&W ammo crossover is not as seamless and trouble-free as swapping .38's into a cylinder of .357 Magnums.

As far as the gunk in the chambers, primer ignition is like pregnancy- there's no "partial" or "halfway". Is that crap in the chambers sooty? Grainy? Is it in all chambers you shot .40 ammo from or just a few? Have you shot more than 1 type or load of the .40's? Is this a factory load or your handload? Lastly, if it is your handload, would you give us the particulars of this load please.

I know this is a lot of questions (heck, it was a lot of typing!) but these are the details that will help us to help you.

[reddog81]

Also, my 40s were printing high - I thought this was odd.

Slower bullets are in the barrel for a longer time while the barrel is recoiling. The longer a bullet is in the barrel, the higher the muzzle when the bullet leaves the barrel.

[BigAlofPa.]

I have a blackhawk 10mm. It came with a separate cylinder for 40sw. I like the gun a lot.

[tazman]

Slower bullets are in the barrel for a longer time while the barrel is recoiling. The longer a bullet is in the barrel, the higher the muzzle when the bullet leaves the barrel.

Very true. I experienced this with my 357 mag revolvers when shooting light versus heavy loads. The light/slower loads shot high.

[Jtarm]

I haven’t had any trouble with .40s in my MC with either TK or Ranch.

10mm is pretty much a slow-fire proposition for me, so I don’t even bother with clips.

[44Blam]

There is nothing wrong with the primer appearance on your .40 S&W brass. You have a firearm that was built to fire a cartridge with a Large Pistol Primer. You are now firing a Cartridge with a Small Pistol Primer in that gun. The tip of the firing pin will obliterate more of the surface of the the small primer than the large one. I can't tell from the picture, but are these the 2 cases that you said have pierced primers? Again, pierced primers are often an indicator of excessive headspace. Taken in combination with your claims of misfires, and many statements from other people trying the same gun/cartridge pairing that you are (this is not the only gun forum where the moon clip thickness is being discussed) with the same issues, the cause AND the solution become quite easy to work out-

Either replace your moon clips with the TK Custom clips, or shoot 10mm ammo in your 10mm firearm. The 10mm/.40 S&W ammo crossover is not as seamless and trouble-free as swapping .38's into a cylinder of .357 Magnums.

As far as the gunk in the chambers, primer ignition is like pregnancy- there's no "partial" or "halfway". Is that crap in the chambers sooty? Grainy? Is it in all chambers you shot .40 ammo from or just a few? Have you shot more than 1 type or load of the .40's? Is this a factory load or your handload? Lastly, if it is your handload, would you give us the particulars of this load please.

I know this is a lot of questions (heck, it was a lot of typing!) but these are the details that will help us to help you.

Those cases were not the pierced ones. Thats what a lot of the primers looked like.
The crap is grainy and in all chambers. The load was 7.9 grain aa7 under an 180 grain boolit. I shoot this in my glock and have no crud at all.
I recently bought some tk clips, but these were shot with ranch clips. When shooting the 40s, it bound a lot...

[samari46]

Supposition,is your chamber set up so that only the 10mm cases have something to stop against?. The 40 S&W cases being considerably shorter and no stop have all that energy pushing the cases further into the chamber and even if you do manage get a few to go off all that energy is being wasted on the 40S&W cases getting pushed further into the chamber that could be the cause of getting misfires. Firing pin hits the 40S&W case both igniting the primer and pushing the case further into the chamber. Just keep using the 10mm cases and no problems. Frank