Some had problems with the rotary primer system on the 650. Kept clean, it worked fine but it need to be adjusted right.
To answer the complains, Dillon changed the primer unit for the same system as the 550. Well, they forgot the moto..if it’s ain’t broken..don’t fix it..many prefer the 650 over the 750. I do prefer the 650.
I have a 550, 650 now and a Super 1050. I think the 750 is a fine machine except that if you tasted the 650, hard to prefer the 750 thereafter just because of the primer system seem better on the 650.
I have the 650 for over a decade. I didn't load much with it compared to others. Close to 10k rounds but I always fear of primer detonation. But it's been functioning fine just a few rouge upsidedown primers. Maybe a few crushed ones and no detonation but I don't remember anymore. Too long ago. That said, I pay special attention if seating the primer feels 'off' but I still reload with ear muffs on.
I recently bought a750 so that I can have small and large primer presses setup at all times. It gives me a piece of mind now that I won't have to worry about full tube detonation. I did some dry runs with the primer system. Seems good to me except that when the tube is down to 1 or 2 primers, it will not always feed it. Don't know if that's normal but I doubt I'll let it get that low anyway when I'm reloading for real. Or maybe after a few hundred reloads, things will smooth out and break in properly.
UPDATE: I reloaded 30 rounds of 500 mag. Powder charger needed lots of tweaking. The rod that pulls it back down is bent in a wrong angle. Compared with a spare rod, the angle is off causing the powder arms to come in contact with the powder charger frame. It got hung up all over the place. Did lots of adjusting, lost the nylon square washer that sides the powder bar in and out. No idea where it went. The nylon square washer went missing for a bunch of rounds, causing even more binding and marred the powder charger frame by the time I caught it. H110 powder everywhere. lol! New starline brass incredibly hard to flare with powder funnel flare. Had to two hand the upstroke and hoping nothing gets destroyed. Gotta say, nothing bad happened. Tough machine. I thought 223 rounds were hard to resize and flare, but 500 mag is bad with the dillon powder funnel flare. The Lee flare is much better but unfortunately, unable to incorporate it.
I experienced 2nd fired cases behaved much better. That said, powder got on the primer seating cup. Now I see small powder impressions on the face of the primer. Now, that's alot of force to seat the primer. Doubt that'll do anything overall, but it's annoying as heck when there is no way I can keep the 750 free of powder on its surfaces because of the sudden jolt when the case becomes free. Other than that, the primer feeding system works reliably until I get down to the last few. It may or may not grab a primer from the tube.
Final UPDATE (I think): I did some reading after having a terrible time with new starline cases sticking to the powder funnel. After some reading, reloaders said to rub a tiny bit of case lube on the powder funnel. I thought about it doing it before but opted not to since it is suppose to be free of case lube. I guess a little wouldn't hurt and boy did it make a difference. I thought I was going tear the cases apart but the starline cases popped out unharmed.
