I have an 1893 Marlin in 32-40 that has been with the family since it was bought new. WHen my grandfather passed away it was given to me, and I wanted to shoot it some. I loaded up some blackpowder loads for it since I was unsure if it was smokeless safe or not. The load shot very consistently and accurately with one problem. The primer likes to back out of the case a little bit on each empty case. The brass is brand new winchester brass, so it is not a problem of excessive fireings on the brass. Is this a headsace problem?

Most likely you are just experiencing the very low pressures that black powder produces.

It wouldn't hurt to get headspace checked, especially if it is a takedown.

Welcome, and enjoy your new/old Marlin!

I am thinking about trying some light smokeless loads. Had a few people tell me to try a light load of AA 5744 or H110.

Don't know about AA5744, but I would not go around experimenting with light loads of H110.

Don't know about AA5744, but I would not go around experimenting with light loads of H110.

Both powders are listed for the 32-40 in one of my loading manuals. I do not mean less than starting loads, it is just that these two loads listed produce significantly less pressure then most of the other ones. Falling below start loads with 110 is a big no no

If you have published load data - by all means, use it.

My 32 special seems to like 6-7gns of Unique.
Unique is my go to cast load powder, seems to work quite well in most anything.
I wouldn't worry too much about excessive head space as stated your load is not pushing the primer back in under low pressures of the BP.

45th edition of Lyman Reloading Manual has load data for the obsolete 32-40 Marlin made the 93 until 1936.170gr Rem jacketed bullet H.P.C.I. # B822826: 2400 13gr vel 1124 to max 15gr vel 1379. Other powders IMR 4227,4198,3031,4895,4064 & Rx 7 Accuracy load IMR 4198 20gr 1422 fps.factory duplication load IMR 4198 18.8gr 1284 fps.Also data on 164 gr cast with gas check and 184gr cast with gas check using unique,2400 & IMR 4227 If you need this data I can print a copy & send it to you.