Quote from Fishobaby on May 2, 2024, 1:50 am

I have no actual experience reloading 350 Legend, but I've thought about it. It seems that you are shooting a revolver with a 7½" barrel. Since the SAAMI minimum length for this cartridge is 2.125", bullet selection should be limited to those which are long enough to have enough of the shank buried in the case. Ideally, I have read, this shank seat depth should be about the same as the bullet diameter, which means bullets should be .772" in length. Sierra has a new #2755 bullet that is 155 grains that they advertise as being for the 350 Legend. I have asked them how long they are because they don't tell you! The picture is at an angle, but to the best of my ability, I have measured the ratio of diameter to length and determined that they are perhaps .695" long, which would leave .280" shank seat depth. I guess that's enough.

I would think that most loaded rounds that are commercially available are designed to be fired from a rifle that has a minimum 16" barrel, so the powder would burn much slower than if designed for a pistol. The "dirty" that you are experiencing could be the result of the short barrel not allowing for complete combustion. You'll want a faster burning powder, but which powder depends upon the bullet weight and length. As far as published data for this cartridge, it might be difficult to find a recipe specifically designed for the shorter barrel.

I would use QuickLOAD or Gordon's Reloading Tool and go "off book" in situations such as this and work up slowly. For instance, *if* the Sierra 2755 is .695" long and 155 grains, I would put that in QuickLOAD and set it to the minimum length of 2.125. It would show that there is .280" shank seat depth. I would set the barrel length to 7½". By trial and error, I find that Alliant Blue Dot powder has a decent case fill of 90.1% and a fast enough burn rate for the short barrel. QuickLOAD predicts 20.2 grains in a case with 36.8 grains of water capacity will produce 49,985 psi, burn all the powder in the short barrel, and would produce 1842 fps velocity from your pistol. QuickLOAD recommends starting 10% low and working-up. I do not know if the bullet is in fact that length, so don't use that load data! A heavier bullet or a bullet seated deeper, or a copper bullet will produce more pressure, so will require less powder. That is a lot of pressure for a handgun. A .357 Magnum has a maximum pressure of 35,000 psi. The 350 Legend has 55,000 maximum! There's a reason that gun weighs 4.5 pounds! In addition, plated bullets are not intended to travel this fast, unless specifically designed for high velocity with very thick plating.

Quote from Fishobaby on May 2, 2024, 4:21 pm

I heard back from Sierra about the length of the 2755. He measured one at .673", not .695" as I had guessed. They sent me a page of load data for an unknown but presumably longer barrel, which I will attach here. Their data for H110 is very conservative, according to QuickLOAD, which also shows 94% of H110 burned in the 7½" barrel. From a 16" barrel, 99% is burned. There is the case with a gas operated semi-automatic that there needs to be enough pressure present at the gas port to completely cycle the bolt. I have experienced incomplete cycling (short stroke) with light charges of fast burning powder, which would not be a factor in a revolver.

The IMR 4227 burns way slow, with only 83% burned in the short barrel. Accurate 5744 only burns 84%. Accurate 4100 burns 96%. N110 is a Vihtavuori powder which burns 96% also, but is bulky and would require a compressed load to approach maximum pressure. My QL doesn't have data for 300MP, which I think is Alliant 300 Magnum Pistol.

The Sierra data shows this bullet loaded to 2.140", which he says is 69% of the diameter and with the cannelure in the case. Other options for the 7½" barrel with the Sierra 2755 bullet loaded to 2.140" and with more complete burn, according to QL:

Vihtavuori N105– 19 grains 88% casefill, 49,243 psi, 1802 fps
Alliant Blue Dot– 20 grains 89% casefill, 48,371 psi, 1821 fps