Book vs Powder?

[Quinc]

Thought this was odd

Hodgdon H110 Powder Vs Lyman 49th

.357 Mag small magnum primer:
Hodgdon rec: 13.5gr Bullet: 180gr COL: 1.575 FPS: 1396
Lyman rec: 13.9gr Bullet: 180gr COL: 1.585 FPS: 947

Lyman uses .4gr more powder and gets almost 500fps less? Even the max load from the lyman book of 14.5 only shows 1101 FPS. Maybe Hodgedon is using an 8-10" barrel?

[NotEnufGarage]

Could even be from a lever action rifle.

[Waldog]

Powder companies report velocities that they get from their ballistics lab pressure guns. Pistol cartridges are shot from barrels that are usually much longer than standard guns. Measuring velocity and pressure is pretty much standard electronic measurement and similar from one company to the next. No body uses CUP (copper crush) measurements anymore. What differs, is the length of the test barrels. And, it's different form one company to the next. I read an article on lab testing of 45acp cartidges. The test gun was a Remington 700 action with "swap-out" barrels. All the barrels were like 24" long.

[Bill Steele]

Given that 1400fps should be attainable with a 180gr bullet in a 6" barrel, I would suspect the Lyman's data may an error. Even a 2.5" snubby should get you in the 1100fps range. I don't shoot these hot of loads out of snubbies, so this is just a guess.

[meaty-btz]

Also, not all bullets are the same (COL & COEFFICIENT). Dunno otherwise. I have noticed that loading books have been odd sometimes.

[Sunday]

All the manuals loading data is somewhat different . That is why they recommend to work up loads. Tolerance in powders, bullets, cases, temperatures and measuring equipment.

[Quinc]

I emailed Lyman, I will post what they say if they get back to me.