Wiley Clapp GP100 10mm Revolver

I ordered a Wiley Clapp GP100 10mm revolver. Can I also shoot .40 S&W rounds out of this revolver? I heard on youtube that it will not shoot .40 S&W rounds just 10mm and I thought that was strange.

I have a Match Champion in 10mm/40 S&W. I haven't paid much attention to the Wiley Clapp model. What does the Ruger factory site say about it? Mine says it'll shoot both. (And it does.)

The issue here is the two cartridges have different extractor grooves and require two different moon clips. I use those from TK Custom, .032" for the 10mm and .040" for the .40S&W.

My 10 mm Match Champion shoots either with the factory moon clips. I wonder how the 10mm and 40 both use the same shellholder on all of my presses. Bob!!

I use Ranch Products moon clips & they work fine in my MC AND my S&W. I just ordered more Ranch moons for my LCR 9mm, and my MC while at SHOT.

Short answer: Yes. There isn't any reason you can't shoot .40 S&W in this gun. Just be advised you may have to scrub the chambers thoroughly to ensure 10mm will easily chamber.

Well I got the revolver and sent it to Mag Na Port and just got it back. I loaded 25 moon clips up with .40 S&W and out of 150 rounds, 26 of the 40's failed to fire with the standard moon clips that come with the GP100 and that Ruger sells for the GP100. I then loaded up 25 more moon clips with 10mm and all 150 rounds fired with the 10mm ammo. So the .40's will fire most of the time but I will not carry the gun with .40's as they are not 100% reliable like the 10mm rounds are. I will shoot the gun for fun with the 40's. Thanks for all who replied to my original post. God Bless.

The issue is that Ruger marketing decided that people should be able to shoot the 10mm/40sw round without moonclips. And even though this is actually impossible to produce reliably they persisted. So instead of headspacing off the moon clip, like s&w does on theirs, you get this. I would try making moonclips of different thickness that you use caliber specific.