Novice's experience with the Ap5-p
I decided to buy the Century Arms Ap5-p a month or so ago. I wanted to use the gun with a can, of course, so I changed the LP to a 90 degree to get the best of both worlds. Immediately the trouble began. I had double feeds or FTE with every mag, especially while unsuppressed. I began scouring the subreddit for solutions. Changed the extractor and the spring, which didn't help. If anything, I was jamming every 2-3 shots. I changed the ejector lever. Bought HK mags. Nothing. I tried both 115 grain and 124 grain ammo. No difference. I disassembled, cleaned and oiled the gun many times, checked the pic rail clamp, checked bolt gap. I reviewed armorer videos on YT trying to find the small detail that I was missing.
Yesterday, I was at the range with an engineer friend. He wanted to shoot the AP5, but I told him it was a lemon. We tried it regardless, with many jams ensuing. He did notice one thing: Using the suppressor with the factory locking piece, it did seem to cycle better for a few shots. I jumped back online and realized a piece I missed: Breaking the gun in with 9mm 124gr NATO ammo. I didn't know Nato ammo was spicier. I startes paying attention to my ammo's FPS. My 124 gr was rated 1090 FPS, too weak to cycle a new stiff MKE spring. I went out and bought Winchester 9mm NATO fmj, rated at 1200 fps and went to the range.
It worked. I had about 300 rounds through the gun, but plagued by failures. I ran 150 rounds of 9mm NATO ammo through it in an hour. I had 2 jams on the first 50 shots, but the latter 100 went without issues, and that's with both MKE and HK mags. It even began cycling 115 grain 1100 fps rounds with one or two FTE in a whole box. The gun started shooting softer and straighter. It's like a switch flipped to make it work. Trying the previous 124 gr 1090 fps ammo resulted in constant jams again.
Moral of the story: Break the gun in with the correct ammunition. Most posters here do the same thing I did. Have a few jams, and then run to change every lever and spring available. It seems dumb in retrospect, but I rarely saw specific ammo types discussed. I hope this helps other new owners.