Due to inability to find the powders I would like to use I worked up a load for powder I had sitting: Herco. Posting results in case it might be helpful for someone that can find it.

Fiocchi Hulls - Cut to 2.60" (OK so not exactly 2 1/2", but that's what my cutter was set to)

Fiocchi Primers - whatever primers come in Fiocchi primed hulls - I _ASSUME_ they are Fio616, but I don't know because the bags are not marked.

Powder - Herco, an old can I had laying around. I tried 22, 22.6, and 23.0 grains. The lower charge weights did not have consistent enough velocity for my liking, and I am posting the 23.0 grain load.

Wad - SG16

Shot - 420 grains (OK - not exactly 1 oz either!!) of lead 7 1/2 chilled.

Overshot card

Crimp - Roll crimped with PRI roll crimp tool to +/- 2.4"


Results per pressure testing at Precision Reloading:

Average Velocity 1,273 fps Standard Deviation: 19 fps Extreme Spread: 52 fps

Average Pressure: 6,797 psi Standard Deviation: 337 psi Extreme Spread: 810 psi

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Thoughts: This roll crimp load required 1/2 grain more than published fold crimp loads to achieve published velocity, but did so about 1,500 psi less than loads as published by Ballistic Products

I was not happy with the extreme spreads of lower charge levels, but I am confident this load is still safe in my 1920's Belgium SxS

Time will tell whether this powder might result in "bloopers" if re-tested in cold weather. Hopefully not, because ammo and powder is in short supply.

Hope that helps. You are responsible for your own loads, and load development. Check loads against published data. I am not responsible for you hurting yourself, this load appears safe in MY gun.

Thank you for posting.

I shoot a lot of 2.5" shells in my old shotguns. That seems like a pretty good hunting load. Does Precision publish any of the loads they test for customers?

How is Herco for temperature sensitivity when the temps are cold?

That's a great question. I wish I knew what to expect in the cold. I know Herco is a slower burning powder and lower pressure loads and slow powders can be an issue in the cold. Unfortunately I'm a bit stuck with what powder I have available. According to this http://www.armbrust.acf2.org/primersubs.htm the Fio primers are middle of the road on the "hotness" scale......whether that will be enough to overcome any cold sensitivity IDK.

I was concerned a bit with the wide extreme spreads at lower charges, so that doesn't bode well. Perhaps a freezer test with a few loads over the magnetospeed are in order before hunting season. If I can manage a test run I'll post results. I only have 100 of these primed hulls and I hate to waste many not knowing about supply.

I only found steel and bismuth load manuals on the Precision Reloading website, so AFAIK they do not publish tested lead loads.


BTW Dukxdog I've enjoyed your reports and great pictures from your hunting camp you've posted on the forums over the years!!!

I picked up a keg of Herco at a recent gun show. I have SG16 wads, etc so can duplicate your load then put in the freezer to find out.

***Thanks for the mention of my pheasant hunting house. I love it out there in South Dakota as do the guys who come to hunt.

OK, so I was able to load 10 rounds of the above load and do some cold soak testing. The results were not great. The load lost slightly more than 10% velocity between 70 degrees and 32(ish). I've never done this before so I don't know what to expect exactly.

Ambient Temp: 46 deg

Chrono: MagnetoSpeed V2 set to "shot/slug"


Sanity Check: 2 shots of RST 7/8 with an advertised velocity of 1,125 fps

Shot 1: 1,064
Shot 2: 1,091

Ambient 46 degrees Shot Test - Load from OP - Fiocchi - 420g pb 7 1/2 - SG16 - 23.0 g Herco - Roll crimp to 2.4"

Shot 1: 1,207
Shot 2: 1,179
Shot 3: 1,161
Shot 4: 1,183
Shot 5: 1,146

Average: 1,175
SD: 23

Cold Soaked Test - Load from OP - Fiocchi - 420g pb 7 1/2 - SG16 - 23.0 g Herco - Roll crimp to 2.4"

Procedure: 5 rounds placed in the freezer overnight. Rounds transported to the range in a cooler with cold packs. Barrel and receiver cold soaked for 5 minutes with cold packs before starting the string, and for 2 minutes between each shot. Do not have a non-contact thermometer, but I believe the freezer and cold packs are well below freezing, but who knows.

Shot 1: 1,125
Shot 2: 1,164
Shot 3: 1,100
Shot 4: 1,129
Shot 5: 1,167

Average: 1,137
SD: 28


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Thoughts: The load lost considerable velocity from room temp down to 46 (approx 100 fps), and another 40 fps when cold soaked down near freezing. I'm a bit disappointed it lost that much velocity, but I know low pressure loads are reputed to be temp sensitive. The loads shoot, and velocity SD doesn't seem to indicate it has become unstable at below freezing temps.