What types of failures are you getting with 115gr?
Mine took about 400 rounds till the stovepipes stopped.
Ignore the run it wet advice, the rifle, just like any AR needs to be lubricated properly not just drown in oil to where it's oozing out of everywhere.
If it's been cleaned and lubricated the problem lies elsewhere. They come pretty gritty from the factory so a proper scrub is needed to start with.
The factory spring feels pretty soft to begin with and the buffer seems to be just a standard carbine buffer so not much to gain swapping things around in there. I did swap mine out but I don't think it was necessary as it was running well before I changed them, just wanted to fiddle around with it and I already had the parts sitting around.
Are there any weird wear marks on the bolt or inside? Just wondering if there is some excess drag from something not sliding like it should.
If all else fails just stick to the 124gr for another couple hundred rounds and then try the 115 again. My FX-9 is definitely becoming more reliable the more rounds it eats. I don't think I've had a failure in at least 200 rounds with my 124gr handloads and I'm guessing my rifle is up around 600-700 total now.
so it turns out the buffer in the FX9 is NOT a 9mm carbine buffer and even lighter than a H buffer. the buffer in mine weighs about 2.8 oz which is lighter than the 3.8 oz H buffer. The Odin buffer weighs empty 2.8 oz which means making the buffer lighter is not an option ...
its also strange why it runs such a light buffer since it is mostly like a 9mm AR ...
Correct, not a 9mm buffer. Probably because this is not a 9mm AR. This has a shorter receiver and an entirely different bolt. My guess is that they built it to be as cheap as possible meaning no specialized 9mm parts for the common items.
When changing out buffers make sure your replacement is the same length as the original. This is extremely important as one of the guys on this site broke the pin off the top of his bolt (the thing the charge handle grabs and also keeps the bolt from rotating) when he swapped in a different buffer.
One word of caution to all owners, Freedom seems to have messed up the design of the bolt a little, if you run ammo that doesn't chamber fully the gun will still fire out of battery resulting in case failures. I posted pics of mine in the main FX-9 thread when I tried some handloads I had left over from a pistol I sold a couple years ago that bulged and one blew out, I ended up with a piece of brass in my arm.
Follow the manual and stay away from aluminum case ammo and make sure any loads you are going to run pass the plunk test in the chamber, make sure they go in cleanly.
This thread probably should have been added to the 33 page owners thread a little ways down page 1, I'm hoping it becomes a sticky soon. This has all already been talked about.
