Range issue today, 2 SP and one failure to fully breech.
BTW, I was shooting my normal range ammo, Sellier & Bellot 180 gr FMJ. Also, the gun was perfectly clean when I started shooting today. In addition, at the start of today my XDm had operated flawlessly for a total of 300 rounds. However, that was with the magazine that I have labeled as # 2.
It happened within the first 50 rounds and it was magazine related. In the past I have kept my # 1 magazine loaded with home defense rounds and take the # 2 magazine to the range. I picked up an additional 4 magazines last weekend so today I took both # 1 and # 2 to the range today. Because I hadn't actually cycled the # 1 magazine I decided to shoot with it today at the range. For the first 15 rounds the magazine functioned perfectly. However, on the second 10 round load I had an SP with 2 rounds left in the magazine. The round was trapped between the breech face in the feed ramp on the barrel pointing up. I dropped the magazine, cleared the gun and looked at the problem round closely and didn't see any visual defect so reloaded it and finshed off that magazine. The next batch of 10 ran perfectly. Then on the 4th magazine load, I had an issue where the slide didn't close completely, pulled the trigger and nothing, not even a click. Dropped the magazine, cleared the round from the chamber and looked for some reason why the slide didn't close, absolutely to clue at all, no dents bulges or anything visual, it looked factory fresh. So, I loaded it back into the magazine and on the 9th round out of 10 had another SP identical to the first. At which point I put magazine #1 in the case and loaded up magazine #2. Which ran flawlessly for the next 110 rounds thru the gun.
I also had 3 incidents where the slide didn't lock open on the empty magazine but I believe that was my fault. Two of those failures to lock open were with magazine # 1 and it happened once with magazine # 2. I have been gripping the the gun with my thumb resting lightly on the slide release. When I got home I experimented with how much pressure on the slide release it takes to prevent the slide from locking open and found out that it isn't much at all. This week I plan on working out on gripping my gun with my right thumb trapped in the grip recess under my left hand.
Anyhow, when I got home first thing I did was strip the gun down and gave it a good looking over. Then I got out my Dumore grinder and a felt wheel and gave the feed ramp a moderate polishing. At this point I don't want to go all out in polishing the feed ramp because I am concerned about re-shaping it. Currently, I now have the top 2/3 fully polished with just a slight hint of haze on the bottom third. At the same time I did a very light polish of the entry to the chamber of the barrel, basically just enough to knock down the roughness without changing the size or remove the witness marks from the original machining. Then I did a light cleaning but didn't bother with flushing out the frame.
Next I took moth magazines apart and compared the springs. I am not sure it was the cause but both springs have a slight kink to them on the last coil by the follower and that kink was slightly different. On the spring for the problem magazine there was just a bit more bend to that kink, about 1.5 wire diameters different at the end loop where it contacts the follower. Which means that the problem spring may have been putting a bit more pressure on the rear of the cartridge. My theory is that near the end of the magazine it may have presented the round a bit nose down into the feed ramp, causing it to bounce instead of slide. So, I have now bent the spring so that it matches the spring from my # 2 magazine. I am also thinking about getting some Boeing water soluble paste we use at work and lubing up the follower.
As for the shooting, it went pretty well. Spent most of my time doing failure drills from 20 to 40 feet. At 20 feet I was about 8 out of 10 hitting the target zones with all 3 rounds but my shooting at speed at 40 feet needs work.
I'll be hitting the range again next weekend and will report back here on how well my tweeks worked on fixing the FTF issues with my # 1 magazine. I also think that I'll be testing the function of all 4 new magazines to make sure I don't have an issue with any of them.