In magnum calibers do you think barrel length has a signifigant effect on terminal performance of bullets?

Depends on the powder. The WIN 296 loads in .357 are much faster in my 8 3/8 barrel.
The reduced loads with fast powder (HP38) don't lose so much in shorter barrels.
So slow powder and long barrels give higher velocity. IN my 3" model 65, I see no point in using the 296 load, because there is little velocity advantage and lots of blast.

Then the question becomes "What velocity does your specific bullet need to expand?" Some hollow points don't expand at low velocity.

Most manufacturer data on velocities is taken from a 4" vented test barrel to simulate firing from a revolver so what you measure over the chronograph in my experience will be very close to what they list.

Your change in velocity will usually be 50 to 75 fps per inch of barrel length from 4" in revolvers with 2" to 8" barrel lengths. While a longer barrel than 8" will show increased velocity the gain per inch begins to decline so an 18" barrel on a .357 mag carbine is unlikely to yield an increase of 700 fps over a 4" barreled revolver but rather a 400 fps increase is more likely.

I can tell you that a Remington .357 125 gr. SJHP goes about 1450 fps. from a 4" barrel and yields around 580 ft. lbs. of energy. The same load delivers 1600 fps./700+ ft. lbs. from a 6" tube. That's a big increase in energy. As long as the bullet isn't pushed past the maximum velocity it's designed to operate at, I'm guessing it will be more effective, however the biggest plus for me is increased sight radius because shot placement is more important than power.

It depends on the guns in question and the load in question. Terminal performance depends on the bullet used, the medium into which it's shot, and the velocity at which it's launched.

Barrel length may affect velocity, one of the components of terminal performance. Depends on the load and the gun that are in question. I've had a 6" King Cobra tube shoot a given .357 Magnum load (180-gr hardcast, max with Blue Dot) only a dozen fps faster (1242 fps) than a 3" S&W 65-5 gun (1230 fps). (This, frankly, shocked me.) The same load was about 400 fps faster in a 20" carbine. I have a friend whose 4" Model 19 always shoots slower than his 2.25" SP-101 - with any load.

I've played with this sort of thing a lot, and in my considered opinion, the only way to say anything for sure about an individual gun and an individual load is to get out the chrono. Seriously.

True story. We go on a call to a townhouse. This guy is sitting in his chair on the second floor and a bullet rips thru the wall about 6" from his head hits the wall across from him. He calls the police, we assume it came from next door, so we order the tenants of the next unit out at gunpoint. We find it came thru both their walls. We order the tenant of the next unit out (end one). We find the entrance hole on the exterior of the building and determine the shot was probably fired from outside the building and an upwards angle (from a passing vehicle we summized). Went thru the exterior sheating and aluminum siding, some 2x4's, 5 or 6 layers of drywall. When I dug the slug out of the wall, it looked to be a .40/10mm FMJ, totally intact/undeformed.

Robo,
I'll bet everyone ordered the Kevlar bath tubs after that?
For SLEEPING in!

in one of the older Speer reloading manuals that had the chronograph results with different loads and barrel lengths in revolvers. there doesn't appear to be rhyme nor reason for why the varied so much other than being different guns. the only way to know for sure is buy a chronograph and shoot your loads with your guns over it

quote:

there doesn't appear to be rhyme nor reason for why the varied so much other than being different guns

I think the rhyme and reason become more obvious when you know how fast or slow a particular powder burns. In my actual testing slow burning powders gain more significantly with longer barrels, but faster burning powders show much less improvement with the same longer barrels.