Bullseye wrote:The bottom edge of the bolt face should have a slightly rounded edge and not be capable of digging into the bullet nose as it rides over it.
This picture shows a typical Mark III bolt face. You can see the edge where the case rim is picked up out of the magazine has a slight bevel to it. No sharp edges should be found here.
The magazine follower spring could be weak too leaving enough slack for the bolt to drag the bullet nose upward. The tension should be great enough to prevent friction from moving the underlying cartridges.
R,
Bullseye
I want to give an update regarding my Cobalt, but first, I want to say "thanks" Bullseye for the website. It truly has been an invaluable resource over the years.
Yesterday I installed a TK bushing and their slingshot mod. Nice updates but it did not affect the gun's reliability to any degree, nor did I expect they would.
Today I made two trips to the range and spent three sessions working with the Cobalt trying to get it working properly.
Last night I did some closer comparisons of your picture above with my bolt, along with comparisons to my MkII bolts. The lower edge of my bolt face did have a sharper edge so I took a small jeweler's file and put a slight radius there and polished the surface. Nothing dramatic, just enough to see if this was the problem. Well apparently it was because today I did not get a single double feed with any ammo, last two rounds or otherwise. I fired at least 400 rounds. I'm not sure if it was a symptom or a cause, but I'm calling that one solved!
I have also been getting rounds that are sometimes feeding too high and hanging on the top of the chamber or on the roof of the receiver. I remember reading somewhere on here that this can be caused by rounds not sliding easily under the extractor as they are stripped from the magazine. To help facilitate this I put a very slight radius on the "bottom" of the extractor at the edge, very similar to the pic above and the factory extractor. This did not seem to help much, but at least it didn't get worse! Upon further inspection I noticed a slight burr on the horizontal edge of the bolt face recess just below the cutout for the LCI. I lightly filed the burr (or sharp edge) away until a cartridge rim would slide more easily into the recess on the bolt face and under the extractor. This made a noticeable improvement. It actually runs flawlessly on Federal Auto Match and Federal Champion, a dramatic improvement from the initial outing!
I would say the gun is about 94-95% now. I still occasionally get a round hanging on the top of the chamber but this happens only with Mini-Mag HP's and Rem Golden Bullets, which are also HP's. The fact that both are hollow points may be the issue. I need to check to see if I can find some round nose Mini-Mags and try those. Yeah I know, good luck huh?
Except for this 22/45, I don't own Ruger Mk III's any longer because I prefer the Mk II's. The last two I did own, I don't recall having any functional issues with either of them. Though I do recall sending one back to Ruger because the receiver had somewhat of a loose fit to the grip frame. Even so, it worked great and it was always the "other guy" who had problems with their Ruger 22's. Not this time, mine has been troublesome at best. I wanted one because I think the concept is great, it's very light, and I think it will make a great host for a suppressor. This particular one has proven to be remarkably accurate and, despite the heavier trigger, it's every bit as accurate as any of my Mk II's, including both of my Government models!! This is why I have stuck with it, trying to fix it, and not traded it on another. I still don't have full confidence in it like I do with my other Rugers, but I'm still working on it...
Thanks to blue and Charles for the input. Thank you again Bullseye for the website.