I have a Yankee hill AR15, I have fired roughly 2000 rounds through it.
I never had problems with the bolt catch, catching the bolt after last round was fired until recently.
I cleaned and checked gas tube, cleaned and checked gas rings on bolt, checked badlever to make sure it was not hanging up and preventing the magizine follower from holding bolt catch up when quickly charging the rifle by hand.
I was shooting tula ammo yesterday and it worked flawlessly.  So I tried a few mags with five rounds each of my hand loads.
I'm loading a 55gr fmj bt with 25.5 grains of IMR 4064, using LC brass and wsr primers.
When firing my reloads sometimes the bolt would catch after last round and other times it wont. i tried shooting a few mags of my reloads thru my buddy's Bushmaster. His rifle worked perfectly with my ammo and magazines I was having problems with.
So my question boils down to this, could it be possible that I have just worn bolt catch down to far and that the hotter reloads I'm shooting  are causing the rifle to cycle faster and slide over the bolt catch?

Thanks for any help

I tested my buddy's lower with my upper, ammo, and mags. His lower caught the bolt each time last round was fired. So leads me to think my problem is a worn bolt catch. I would hate for that to be the case though since I don't have alot of rounds thru it. But I ordered a few different bolt catches and will install them when I get them

It doesn't seem logical that there could be a direct relationship between your handloads and last round lock-back failure. While I'm not personally familiar with IMR4064, it's mid-way between Win 748 and H335, two propellants I use extensively, and that load should produce ample power for proper cycling. That said, the moment you said "BAD lever", it conjured problems I had with the device, especially in 20-round Gen 2 PMAG's, so where *I* would start is with first different mags if your inventory includes those, and second with re-testing without the BAD lever.  HTH.

I have tried all different mags that I own and friends own...tried 30rd p mags gen 1-3, 30 rd gi mags, and other random polymer mags I have aquired.  My problem was still there. I'm going to remove my B.A.D lever tonight,  hopefully that's the culprit.

It has been for a lot of folks. Strangely, others have used it without trouble, which makes me suspect that the shooter's hold is a variable in the equation. I had problems mostly shooting rested, with 20-rounders, and got so disgusted with the randomness that I shed both the straight-body 20's (Gen 2) and the BAD lever; no problems afterward (and no problems with Gen 3 PMag 20's.

most problems that come from the bad lever are because it was not fitted to the paddle correctly . for mine to work correctly I had to grind off the checkering on the front face of the stock paddle to get the 2 pieces of the bad to come together correctly .. and not one issue since on any of my ar's and they all have a bad on them

That's what's odd...I have fired 2000 rounds through my Ar15 with the bad lever installed without any malfunctuons. The failure to lock the bolt back after last round fired every time started happening recently.  I fired 100 rounds of assorted factory ammo in many different magazines and had no problems. As weird as it seems I'm only having the problem with my reloads on my rifle. My friends ar's have no malfunctuons when firing my relaods. Very strange to me...

maybe your bolt hold open spring is worn out

Removed my B.A.D lever and the problem with not locking the bolt back after last round went away.
crazy I didn't think there was enough extra weight with it on the bolt catch to cause malfunctions.
With the IMR 4064 I'm loading at 25.5 gr, I'm not having any problems with not enough gas coming back through to cycle the bolt.
I have a seekings precision enhanced bolt catch and new bolt catch spring i will install today. :)

I have had a few more failure to lock back after last round fired. I replaced the bolt catch and spring. Guess I will be buying some heavier bullets to load with the IMR 4064 and see what it does.

did you leave off the bad lever or put it back when you put the other new pieces ?