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I have a FN 509T with a Henry Holsters FN 509 Tactical Compensator feeding issue. I have tried both spring. I am using 115g target ammo. What ammo works?
Hotter ammo. Blazer Brass 115 grain runs in my 509T with the Agency Arms 119, but AE 115 and Monarch 115, it will not 100% of the time. I think I ran about 60 AE before I had a short stroke. Another at the 100 round mark. The Monarch is such a mouse fart load, that about 1-2 rounds per mag would short stroke. I didn't feel that shooting much 115 gave me any lesser rise than using it stock without the 119. 124 you should see a better improvement.

All of the above ran 100% without the 119.
 

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The compensator eats up a lot of the energy used to drive the slide. Running lighter ammo with a factory spring is more likely to have issues.

Compensators work on a volume of gas principle, meaning the more gas you give it, the better it works. If you want to run light ammo and a comp, you will need a lighter (than factory yellow) recoil spring. Shooting hotter loads(higher velocity) will produce more linear recoil, but activate the compensator better and give you less muzzle rise. Only problem is that you wind up with a problem going into battery caused by the striker spring pushing the slide back. The Recoil spring has to have enough force to strip a round off the top of the magazine plus an additional X amount of force, that X amount of force comes from the amount of rearward energy is required to cock the striker into the ready position. What this means it that to run your comp reliably with light ammo lilke a stock 115 gr bullet, you would need to run a lighter recoil spring and a lighter striker spring to compensate, but running a lighter striker spring like one in particular out there, causes light strikes due to insufficient force.

Bottom line is this. If you have a big brute like me with lots of experience shooting guns of all varieties, I can make the gun run in most cases because the mass I can put behind the gun allows it to cycle. If your grip isn't perfect and you're not really "behind" the gun and shooting light 115 gr rounds, you're likely to have ejection and feeding issues. Fry some Fiocchi or some Speer Lawman, they're hotter loads with lighter bullets will make the comp work better and likely cycle your slide better. Make sure your barrel and frame rails are well lubricated with plenty of light oil, that will definitely help with cycling.
 

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I load my own bullets and have found that 115 grain loaded with minimum 4.2 grains of powder (Hogdgon Tite Group, recommended minimum is 3.8 grains) with our without yellow spring in my 509 tactical with PMM comp. So maybe try a +P load? I use synthetic grease lightly on the frame rails.
 
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