I'm having difficulty seating primers in Hornady 7-08 brass. I can't fully seat primers on my Rockchucker press with reasonable normal pressure. I have to slam the handle so hard, I nearly lift my reloading bench off the floor. This happens with new brass, multi-fired brass with cleaned primer pockets, and fired factory-loaded brass. I use Remington brass for all my other calibers and don't have the problem. I'm using Hornady 7-08 brass because that's all I could find when I first got this rifle. The primer pockets measure the same with both brands. I tried lengthening the post on the primer arm. I tried a different shellholder. I tried my old Lee Auto Prime; I can seat the primer, but it takes both hands to squeeze the lever all the way. What's going on here? Anyone ever experience something like this?

If you have some Winchester primers, they should seat easier. They are softer and what I often load in virgin brass. Especially with tight primer pockets.

What primer?

I use only Winchester WLR primers.

Hornady brass is not usually one of the brands with extra tight primer pockets. And Win LR primers are not known as a wide primer. I think you got a special batch of either primers or brass. Lapua brass and Federal primers are such a tight fit, I had to go to an RCBS bench mount primer seater.

I've loaded thousands upon thousands of rounds over the last 11 years. And I can tell you for sure, the last two years primer pockets have gotten tighter in most brands of brass.

Maybe your just getting weaker in your old age?

I have had the same issue with Hornady brass. I have a primer pocket reamer that I have to use on them

No chance

I use 6.5 CM hornady brass and federal primers and have loaded a ton with zero issues. I'd consider at least buying a 100-pack of another primer brand just for a test. Or a pack of another lot of winchesters to see if it was a one-time issue.

I’ve had that problem with Hornady Match brass, but I don’t think they even make that in 7-08

Out of curiosity have you measured the OD of your Winchester large rifle primers? .210 is SAAMI spec. for LR primers. I measured some of the WLR’s I have. 10 averaged . 2107. Minutely larger than Remington and smaller than CCI and Federal.
New primer pockets I have measured have been in the .208 - 209 range. .2085 is SAAMI spec. As long as they will prime, I would be ok with the primers being a little snug....Potentially those tight primers should net you more loadings in that set of brass.

Once upon a time a wise man told me "if it aint tight it aint right"

On a previous batch of tight primer pockets I ran them through the Dillon swager which added a little radius to the lip of the pocket. They still required a little force to seat but they started a little easier.

Measured several primers: Current lot .210" Another lot of Winchester primers .210" Other, brand unknown primers .210-211"

Measured primer pocket on Hornady brass: .208-.2085"

I will check primer arm, shellholder alignment / operation again...and a couple of other things.

Sounds like your brass and primers are in spec. Check under the rim of your shell holder. Make sure there is not a small piece of trash keeping the brass from going in far enough to squarely line up. Last resort, put I squirt of one shot on a q-tip and dab it in those tight primer pockets. Let it dry three or four minutes. They will go in easier. The danger of that is they will come out easier. One shot won’t hurt primer or powder ignition.
Best of luck working it out Papa45

I inspected the primer arm, post, cup, shellholder and piston slot again. They all looked clean, but I cleaned them again and lubed everything lightly. The seating operation seems a little smoother, but I still have to slam about one in eight primers to get it seated properly. Guess I'll just live with it. Thanks for all the help.