Ruger Mark III question

[stinkbelly]

I am a 4H shooting sports leader and we use several different Ruger Mark III pistols. On all of them, when you pull the bolt back, with the magazine out, there is a little resistance about half way back. It seems normal since they all have it. What is causing this resistance?

The reason I ask is because one of them has quite a bit more resistance than all of the others. That one doesn't seem right. The resistance is at the exact bolt position as the others, it is just more.

I have taken them apart looking, but can't figure it out. When I take out the swiss army back of the grip, the resistance goes away on all of them. So I am thinking it is the swiss army part or something that it puts pressure on.

I want to make sure that if that one has something broken or worn that it gets fixed.

[stinkbelly]

I guess you guys are stumped too.

[Gunnyart]

You might have a stiffer mainspring in that one. Try swapping it from one gun to the other and see if the problem follows it.

[WhiplashTX]

The resistance you are feeling is the slide pushing down on the hammer and compressing the main spring. The swiss army part you are referring to is the mainspring housing and as Gunnyart suggested you can try swapping it between pistols to see if it makes a difference.

[stinkbelly]

I took two Mark III pistols apart last night and interchanged their main spring. The one I am having issues with became worse. The other one worked flawlessly with either main spring.

As I played around with them it appears that the resistance may be the hammer like Whiplash said. It appears to push the hammer strut into the main spring every time you pull the bolt back even if the pistol is already cocked. The top of the hammer had two rub marks that didn't look normal. Both main springs felt like they had the same resistance by hand (pushing a screwdriver into them). I am wondering if there is an issue with the pivot point of the hammer.

[WhiplashTX]

The bolt will over rotate the hammer pushing it past the sear so that it catches every time. That's why you feel the resistance even when it's already cocked. The issue could be caused by several things. As you mentioned something could be milled wrong in the frame or upper receiver. The hammer itself could be out of spec or the bolt is out of spec. You could try swapping bolts and see if it follows. Next I would try the upper receiver. The hammer would be the last thing to try but requires completely disassembling two pistols. Regardless, if it's anything but the hammer the cost to fix it would be a lot more than sending it back to Ruger. Have you had any issues with it cycling?


I have a 22/45 Lite and it has a couple of minor grooves in the hammer face where the bolt rides across the top of it. I don't have another Ruger to compare it to so I couldn't tell you weather it's resistance is higher than normal. I do shoot a lot of subs through it and have never had any cycling issues even with the lower power loads.

[stinkbelly]

I have no issues with it cycling. Honestly I haven't played with that one much in the past to see if it has always been this way. It is just different than all the other ones.