Barrel length & velocity

How velocity gain would 4 inches of barrel length produce ?

Lets say, a 24? barrel vs. a 28? barrel, assuming hunting loads, 100-120 grains of BH 209 behind a 300 grain sabot ?

Unknown for sure, but I have heard a rule of thumb is 50 fps per inch?

Not so much you might notice..

I heard the same rule of thumb. 50 fps per extra inch of barrel unless you have maxed the load out.

What powder and what load can make a big difference.
A light load of fast burning powder such as Pyrodex P or 777 FFF would not make much difference in velocity between the 24 and 28 inch barrels.
On the other hand a heavy load of RS or 777 might still be burning when it reached the end of the 24 inch barrel.

Think he is talking about a BH209 load of 110gn.

I'm not sure if this even applies to ML's using subs, but In the Remington Catalog in their ammo section they used to have a chart addressing velocity vs barrel length. IIRC it was 10fps in the 1000-2000fps range; 20fps in the 2000-3000fps range and 30 fps per in for the 3000+fps range. Unless you buy a choronograph to prove otherwise, you're looking at approximately 40fps total. So nothing to be concerned with for the extra weight and cumbersome pointability of the longer barrel.

Near as i can tell, from my data of measured speeds; the speed of a 300g Gold Dot pushed by 105g BH is 1795 fps from my X7, and 1855 fps from my Triumph and Accura. I believe the X7 has a 24" barrel, and the Triumph has a 28" barrel; the Accura has a 27" barrel. So, it seems the loss/gain of 4" of barrel is aboout 60 fps.

Thanks Ron, that?s exactly what I?m looking for.
Considering an X-7 vs. Standard Omega (24? vs. 28?)
Primary target will be elk.
60 FPS is not bad, I can live with that.
I sure like shorter, lighter rifles for carrying around the mountains.
A few ounces can feel like a ton after a 8 mile hike at 9,000 ft.

Our hunting camp is at 6100', and our boy does hunt above 8000' in the Talus. I killed an elk up there once; that was enough. It always seemed weird to us that the elk were up there with the pika. Hope you get more than a raghorn, Raghorn.

Roughly 15fps per inch in a 50cal seems to be about right with most subs and common bullet weights.

Very Heavy or light bullets with max or above max recommended loads might vary a bit more.