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In another post I mentioned a problem with a Federal 510 round deforming and sticking in my Buck Mark. A picture of the casing and other casings I found in my range bag. The one I had problems with is on the right. The one next to it (also federal) has a slight bulge on the base. The others are flat across the bottom. The one on the right expanded enough that it took a cleaning rod to dislodge it from the breech. This is the second time I recall something like this happening. Both times in the Buck Mark. The one next to it has been fired sometime in the last 30 days. I'm not sure if this happens more often or has something to do with the Buck Mark and Federal 510 ammo.

Slightly weak recoil spring , the slide is not always seating or is opening too soon and the pressure rise is bulging the not completely supported case head???? or maybe just some thin brass??? 27F and very frosty here this morning, sunny and 37F at this moment.

Well for the base to expand like that it had to NOT be supported. Which may indicate the chamber is dirty and/or the rounds are sticking. I have seen this in some lead bullets where the lead is maybe a little over size or deformed causing it to stick in the chamber.

Have you tried any different ammo?

I usually shoot a couple types. Yesterday I didn't. The Buck Mark Chamber didn't seem to have any residue build up. Interesting that the slide would close enough to release the trigger, but not enough to support the cartridge base.

Cleaned the pistol and give it another try.


Cold here, also, Len. 41 low and 48 high.

Check the breech face for any lead build up, especially around the corners. This looks like the slide is not fully closed. Other than that your Buckmark pistol may not head space Fed 510 correctly.

R,
Bullseye

have you measured the bullets in that lot with a cliper they might be a bit over spec for the buckmark....or you need a new recoil spring...or a whole new gun!!!!

bgreenea3 wrote:have you measured the bullets in that lot with a cliper they might be a bit over spec for the buckmark....or you need a new recoil spring...or a whole new gun!!!!

Well said, young Greener, now the old guy will bee forced to buy some more new guns. You just gave him the excuse he needed. I will agree with you on the large long bullet hitting the lands in combination with a slightly weak spring, makes sense to me.

Greentop has a couple of used M41's. Wonder what I could get for a BM standard. Obviously, that's the solution.

greener wrote:Greentop has a couple of used M41's. Wonder what I could get for a BM standard. Obviously, that's the solution.

Got ya tinking,eh? What few guns that I have had problems with, that I could not solve with the help of my local smith, I NO LONGER OWN.

I wouldn't initially suspect a weak recoil spring unless there's also evidence of expansion on the sidewalls of the case near the rim. That type of deformation would typically show the case beginning the ejection sequence prior to full detonation and sealing of the cartridge against the chamber wall from a weak recoil spring. If just the back of the case is deformed and the sidewalls are normal, then it would appear to be a head spacing issue as the case is fully seated throughout detonation and just the rear of it is unsupported. Are the original Federal cases in the picture all from the same lot?

R,
Bullseye

I think the other cases are from different lots. Next time out, I'll fire different lots of Federal and track what's been fired. The mushroomed casing looked fully seated. It was also expanded enough that I had to use a cleaning rod to remove it.

Makes sense, with the top of the case mushroomed out like that I doubt the extractor claw had enough reach to grab the rim and pull the case out of the chamber. There's been times where I've had to remove fired, non-deformed cases, and either had to use the rod or a small screwdriver to pry the case loose from the chamber. When they seal, the fired cases seal pretty tightly against the chamber wall. It's the recoil energy that forces them out of the chamber when normally fired, that spent gas causes the casing to act like a piston and pushes the bolt rearwards with great force. The extractor claw just holds the casing in position, it doesn't need to pull the casing out.

R,
Bullseye

I might have finally stumbled across a contributing cause for the problem and the problem I've had with anything but HV ammo in the Buck Mark for a while. I looked at a Buck Mark today at a gun show. The recoil spring guide rod looked straight. Not like this.



Not sure if the guide rods are supposed to be bent in several places, but I think I'll order a new one to find out.

I really don't think it is supposed to be bent, straight makes sense to me.

Looking at that picture it looks like the last part of the rod is bent to where the bolt is not fully closing on the chambered casing. A new one should fix it.

R,
Bullseye