doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 20 ga 2 1/2” reloading data

I was fortunate enough to buy an in proof 20 bore Harkom boxlock at the Southern this spring with excellent wall thickness. The gun is currently with my gunsmith having some cosmetic surgery. Mechanically it needs nothing. However it is a 2.5” Damascus gun. So at long last now that I am retired I am going to take up reloading my own shells.

An experienced reloader friend has set up my new MEC Size Master for me and taught me the basics. I have been reading and researching the process and feel comfortable reloading 2.5 “ Cheddite hulls using a formula provided to me by BP using Winchester powder. I have a good supply of plastic RST 20 bore hulls and I purchased some primed Cheddite 67mm papers. However, I am hoping to find a bigger variety of recipes utilizing other powders.

Published data for reloading 2 1/2 inch 20 gauge shells appears to be very scarce. A friend shared with me the 16 gauge society’s low pressure reloading file and it is robust. I wish I good find a similar resource for low pressure 20 bore reloading.

Any words of wisdom from the group here?

Thanks,
Dr. P

When you find it, please let me in on it. My 2.5 inch 20 ga Trojan needs similar fodder.


To be fair, I don't think a lot of people have spent much time on developing 2.5 inch 20 ga loads.

Low pressure 2 3/4" loads and roll crimp for the 2 1/2" hull. Or if you have old 2 3/4" Win AA hulls which are no where near 2 3/4".

If you decide to use 2-3/4" AA hulls, I have a 3/4oz LP load with 20/28 that I used in my 2-1/2" damascus flues.

I reload for my 2.5-inch chambered 20-gauge Army Navy. I use straight-wall hulls (mostly Cheddite but also Fiocchi, Federal) cut down from 2.75-inch hulls, Cheddite primers, and roll crimping. I have had a number of loads tested by Precision Reloading. The most useful series I tested used the above components, WSF powder, and BPI brush wads (I now substitute BPI SG20-S wads to avoid lead fouling). I tested shot charges of 3/4 and 7/8 ounce, each with 14 and 16 grains powder, for a total of 4 loads tested. Pressures varied between 5K and 8K PSI. I would be happy to forward the full reports if you PM me your email address.

Thank you Hooky….PM sent!

Dr. P

I concur with Eddie. Roll crimping 2-3/4 data into hulls cut down to 2-1/2 is definitely the way to go.

I drew the max pressure line at 8,000 PSI, when picking data to try.

I should add most2-3/4 in 7/8 loads can be roll crimped with cut down 2-1/2 hulls.