M&P 40 Pro doesn't like small rifle primers

[Bill Schwab]

My 1050 and 1911's seem to like Winchester Small Rifle primers, so over the past 12 or so years all 40 & 38 SuperComp ammo has used WSR primers. I just bought a new 40 Pro and like it a lot, but of the 200 rounds through it 3 of the WSR's did not ignite the first time (they had a firing pin dent on their primer). I ran those 3 through the gun again and they ignited the second time. Is this typical of striker fired guns?

[High Lord Gomer]

I've never used small rifle primers in pistol loads but I have had light strike in most of my M&Ps. I now run extra power striker springs in all of my M&P and have had 0 light strikes since. With the Apex sear, I don't notice the extra power striker spring.

[mcracco]

I do believe the cup thickness of a small rifle primer is thicker than that of a small pistol primer and if true the rifle primer would need more energy to ignite. But what's the point of using rifle primers in a pistol in the first place?

[Bill Schwab]

But what's the point of using rifle primers in a pistol in the first place?

WSR primers run smoothly through my 1050, and I only have to stock one size of primer for pistol and 223 rifle. I've used them in 40 for about 10 years, and this is the first problem I've had.

[Bill Schwab]

I now run extra power striker springs in all of my M&P and have had 0 light strikes since. With the Apex sear, I don't notice the extra power striker spring.

Thanks Mike, very helpful. I'll place an order with SSS.

[bigfish]

I have had problems getting winchester ssp to go off all the time in my 9mm pro, but it does have the reduced power striker spring in it. Never any problems with federals. My 40 pro has never had a failure to ignite.

[GlockCanMan]

Once I added the extra power spring my problems went away also. But I was already running Federal Small pistol primers and they are very soft to begin with.

[Bill Schwab]

I'm sending my gun to Dan Burwell for a trigger job and he offers a service for light strikes, here's what he said: "I lighten the striker and set-back the shoulder allowing it to protrude through the breach face further." I'm having that done, and I'll report back afterwards and tell you if the gun ignites Win Small Rifle primers.

[Taylor Murphy]

Thats not a bad idea on using the WSR primers, my hats off to you sir