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I thought this was a problem unique to my Mark II. But my shooting friend recently bought a Mark II that was near new. At the range my Mark II is very sensitive to misfires, his not as much, but still more than I think acceptable. His is stock. Mine has the Clark bushings, Volqs sear and trigger. I made sure the overtravel is set to lift the sear from dragging on the hammer. I've tried both new stock firing pins as well as the Volqs titanium. The imprints on the rim are noticable but not what I consider strong. His are not much better. I picked up some spent brass from a guy that was shooting a S&W and all I could say was , wow, what a difference. The S&W put a deep imprint.

Ammo makes some difference, Rems are bad, Fed bad but not as bad as the Rems, Winchester are the best but still 1 in 20 miss.

My question is to see if there are anyways to improve the strike force. Reduced main springs are available, but nobody make an XP spring. The new ruger spring I put in didn't make any difference. I've though about stoning both sides of the firing pin, the end that hits the primer, to see if a reduced surface area would allow the same force to drive the pin deeper.

Any ideas?

How old is your pistol?

I have an old MKII and I just put a new #KA57 recoil spring assembly and a main spring assembly in mine. Mine was noticeably easier to cock than my newer MKIIs so I changed out those parts for new.

Not sure how old, but old. 15 years I'd guess. I have replaced the main spring and the recoil spring. Tried both new ruger firing pins and Volqs pins. Clark hammer bushings. Volqs sear and trigger. Bolt face looks good and there are no problems chambering. Strikes are consistent on both rounds that ignite and those that don't.

Welcome to Guntalk!

There's a few things to check. One is how much drag is on the firing pin from the bolt's firing pin channel? Does the pin fit snugly or is it relatively loose.

Next, it might not be a matter of pin inertia but one of pin travel. How far can the pin travel when pushed fully in. It could be that the pin stop is preventing the pin from making a deep impression in the primer rim in order to prevent any contact of the pin and the chamber mouth.

Lastly, how does the chamber look? If there's fouling in the chamber, like if someone has been firing Remington ammo, there could be a ring of lead deposits preventing the case from completely seating in the chamber. When the firing pin strikes the case rim it loses some of its force because it has to drive the case against the chamber mouth. When this happens much of the pin's energy has been lost.

It sounds like you've expended considerable effort into locating the source of this problem. There can be several answers that you may not have tried yet. Unfortunately this problem is different to each particular firearm and this means that more than one remedy might need to be attempted. Sometimes simply narrowing the end of the pin can channel more inertia to the case rim. But one must be cautious when narrowing the pin face as not to shorten the overall length of the pin.

Hope this helps.

R,
Bullseye

If all else fails you may want to try this trick.
This fix has held up for several thousand rounds in my pistol.

http://tinyurl.com/2xjd5z

I wouldn't say the pin is loose, but it slides freely without any binding. Without the return spring it will slide with gravity. I did try to enlarge the stop hole but only took off about 3 thou. Maybe I should try a little more. /the above post mentioned filing the pin face 'blunt' but I think its already blunt. I was thinking filing the sides to make it more narrow. Drilling the hammer and filing with lead would be easy, only Ruger won't sell replacement hammers so I'd need to know its safe to do. The chamber is clean and cartridges chamber easy. But I think I'll polish it with the dremel tool to see if I can improve it.

How much should you enlarge the firing pin hole by, 5 thou?

I would not make a general statement as to how much your firing pin hole could be enlarged. This would take a careful measurement with a caliper gauge to see how much clearance is there with the pin fully depressed against the stop pin. I'd measure the depth of the pin tip below the bolt face.

I would also appreciate seeing a few pictures of spent cases with the pin depressions visible. I was thinking of narrowing the pin footprint on your pin but I'd like to see your pin's impressions first.

R,
Bullseye