Hi there,

I have a super accurate M&P R8 revolver.
The revolver is amazingly accurate and reliable in single action mode.

However, I have a big ignition issue when I shoot in double action mode.

I have checked that the hammer spring is screwed tightly.
I have noticed that the problem occurs with any type of ammo and caliber (.38 or .357), with or without using the full moon clips.

I have also noticed while actuating the trigger, that:
1. The slower I squeeze it, the more likely and frequently the ignition won't happen;
2. The faster I squeeze the trigger, the better chance I have to fire the bullet correctly.

- Is it my trigger pull that is wrong? But then, if I squeeze fast, I lose accuracy, AND I AM NOT Jerry MICULEK , ha, ha, ha :-)
- Is it that particular revolver trigger design (BTW, the trigger pull is fantastic and it goes off so crisply and smoothly at the same time!)?
- Any idea?

Many thanks for your thoughts!
Damo

Did you buy new?
Did you or any one else change the mainspring?

It often happens that the firing pin is too short. Measure the firing pin. It needs to be at least .495 overall length, with .500 to .505 being better.
The gun should fire no matter how you pull the trigger.

Also, different brands of primers take different amounts of force to set them off. Federal is easiest, Winchester next, then Remington, and CCI is the hardest of the American brands. Don't know about the foreign ones.

If you put a trigger pull gage under the hammer, it should take a minimum of 44 oz. to just start to lift the hook off the frame for Federal primers, more for other primers.

@ Bigggbbbruce
Yep brand new and nope, factory set-up

@ Toolguy
That makes perfect sense, both the harder primers and the firing pin length, because actually when actuating the trigger in SA mode, it has never failed since the hammer travel is the longest and spring tension the greatest.

Do you know if I could order a longer firing pin from S&W? Note that I am in Europe and not suré the warranty would work here, or perhaps via the German importer which is quite big I believe.

Thanks,
Damo

S&W does not have longer firing pins. Look at Cylinder & Slide or apextactical.com or midwayusa.com.

OK, the clue is in your detailed description of when you have the problem. The issue is operator error. If you're trying to really finesse the shot, there's a tendency to relax your trigger digit as soon as the shot breaks. This allows the rebound slide to move a wee bit forward and bump the hammer as it's falling. This robs enough energy to cause a misfire. You aren't the first and you won't be the last to have this issue.

What you have to do is make sure you pin the trigger all the way to the rear at the conclusion of the trigger stroke. Every trigger stroke.
It's easier if your trigger stroke is faster, but it doesn't have to be convulsive. I suggest dry fire as a means to polish the skill. Just make sure your handgun is unloaded, by visual and touch inspection. When done, put everything away and do something else.

If you know how to, & are comfortable, I'd check the FP length. I have some .489" long ones that have worked flawlessly for years but that length in a different revolver doesn't work consistently. If you do buy a aftermarket FP get the C&S extended length FP.

Another quick thing you can do first, that's less invasive, is to put a fired primer cup, less the avil, between the strain screw's tip & the main spring, where it touches it. That'll give you a tad more tension on the spring to see if that helps.

If that does help it's not the FP but rather the screw too short or the spring too weak. Worth a try.

.

__________________
Waiting for the break of day

@ WR Moore,

Never thought about this - I indeed never had ignition problems with my Dad's 686 (Hammer pinned FP) in DA mode...

I have dry-fired a lot, with snapcaps in the cylinder, and checked that the FP goes right into the primer by keeping the trigger squeezed.

I have also checked the FP spot mark left on primers of unfired cartridges, and the difference between fired shells and non-ignited ones is, say, subtle, but there is indeed a slight one - so confirming your theory about MY squeezing technique...

I will try and work on my trigger pull and let you know!


@Bluedot and Toolguy,

Thanks for the tips, C&S extended length FP and "washer" trick between frame and spring are on my solution list after practicing my squeezing technique ;-)


Thanks guys!
Damo

Putting a shim on the end of the strain screw is good advice whenever there are misfires. However, when increasing the mainspring tension fixes the problem, that does not necessarily mean that this was the correct or only solution.

There are many areas which can cause misfires, such as short firing pin, excessive end shake, friction on the hammer, or off center primer strikes. If any of these areas is only a little bit out of spec, then increased mainspring tension may be able to overcome the problem, but that does not mean that weak mainspring tension was the real source of the issue.

The firing pin strike on fired rounds will always appear greater than the strike on rounds that misfire. When the round fires, the case and primer are pushed back against the firing pin with the full chamber pressure of the fired round. So the indent on fired rounds will appear deeper than the strike that the firing pin actually makes. On rounds that misfire, you see what the firing pin strike really looks like.

I do not accept that your problem is user error. I do agree that the preferred technique for double action is to pull through smoothly and steadily. But many people slowly pre-stage double action triggers, then stop just before the break, and then squeeze through the break even more slowly. I do not encourage this technique, but it should not cause misfires. If this method does cause misfires, I would suspect that something in the revolver was a little out of tolerance.

I also want to mention that extended length firing pins are a bit controversial. Some people have reported problems with some aftermarket firing pins. I am not an expert on this issue, but I recommend doing some research on this forum to make sure that any aftermarket parts that will be added to the revolver are appropriate for your intended use.

R8's have been commonly reported here for light strike issues but it's almost always a backed out strain screw. ( Mine was.) Just for a data point, I'd try this simple test before talking about replacing parts or sending it back. Try temporarily shimming the spring to strain screw interface with a spend primer cup (or even a piece of match book ). If it works, you can either shim it for good or get a longer strain screw. There are discussions/instructions here for how to do it if you use the search feature.

__________________
Dave

sounds like a slow timing issue to me.

Interim feedback

Thanks to All for your contribution and ideas!

FYI, I have swapped the factory FP for a C&S one.

Result: it dramatically reduces the number of DA misfires.

Conclusions:

1. the factory FP is really, really, short (<.475) while the C&S is really, really long in comparison, and definitely protrudes well enough to hit and mark the primers - HOWEVER, I still had misfires, leading me to the next point;

2. the trigger pull has certainly a part to play here, but I let 3 fellow range friends try the revolver, and only one did not have any misfires.

(Note: I never had any such DA issue in my life, and I have shot the following revolvers: S&W 29 Classic + 686, Colt DS + Anaconda, Manurhin MR73 - the Anaconda bearing the Wislon light trigger pull kit, and the MR73 set at its lightest settings too)

3. Next steps are, a) try the primer cup as a washer between the strain screw and spring, both with the factory and replacement FPs, and b) swap the factory spring for a Wilson one...

This said, I find it sad to have to experience such an issue with a Performance Center gun (No way I can get it back to S&W as I bought the gun from a small local smith here in Europe - and yes, the gun was NIB, still "oily" as it left the factory).

One thing is sure, now that I have a longer FP and still get misfires, the spring tention is definitely too light.
The longer FP from C&S is not an issue for me as I have noticed that my Colt DS, that has a hammer pinned FP, also deeply strikes the primer cup, right in its centre.

Keeping you posted...
Cheers,
Damo