A 180 grain bullet leaves the muzzle at 3100fps from a 26 inch barrel in a rifle chambered in 300 Win Mag.Would the same gun with a 36 inch barrel create a muzzle velocity of 3600fps.?

Nope. Only if you put a lot more powder and and a bigger case. In the same cartridge it would probably be SLOWER than 3100 with the same load. At some point acceleration stops and friction takes over.

Akuma,

No need to stop your questions, that's how we learn!

As far as velocity gain/loss, generally, you will gain/lose 30-50 fps per inch of barrel for smokeless rifles and pistols. Then again, you can see +/- 50-100 fps between different barrels/chambers of the same chambering and barrel length.

I don't know at what point you will stop seeing velocity gains in a 300 win mag, but I would expect to certainly see velocity gains on out to 30 inches, or perhaps a bit more. That said, I'd expect to see a 200-300 fps gain for the 36" tube.

If you are going to the expense and trouble of building a long barreled gun, extra long barrels are available but at a premium, I'd want a 300 ultra mag case at a minimum to take advantage of the long barrel.

Akuma-

Why is it your last question?? Stick around.

You would gain only 250fps with 36inches of barrel.

Akuma, the problem with getting a barrel that long is the weight. Without building a custom support near the center of a 36in barrel it's own weight causes it to bend and apply tourque on the action and bedding. Since this is not economical in the long run, add the extra weight the tension and it really isn't worth the extra 250fps. The max barrel length I would use is 30inches.

Why does this have to be your last question?

I ran this through QuickLoad software last night. First I put in a load that gave 3100 fps with a 180 Nosler Partition in a 26� barrel from a .300 Win. Mag. Then I increased the barrel length to 36� and the velocity was only 3280 something.

Next I ran the powder comparison with a 180 grain bullet in a 36� barrel and asked it to list the charges of powder necessary to achieve 3600 fps. Even with the slowest powders at over 125% loading density it needs pressures above 80,000 psi to reach this velocity. The �normal� .300 Win. Mag. powders, like IMR4831, RL-22, even RL-25, need something in the 90,000 to 100,000 psi range to get this velocity. And no, I will not list the powder charge weight necessary to do this!

Forgot to add - the SAAMI maximum working pressure for the .300 Win. Mag. is just over 62,000 psi.

[This message has been edited by Jim in Idaho (edited 03-22-2002).]

I like this forum!

Akuma, look at the amount of help, experience, opinion and downright decency available to you here... I've never met any of the guys who responded to your question (I hope that changes), but I've corresponded with several (heck, Bob and I are downright pen-pals at times!).

Having said all that, stick around, don't be bashful and never quit asking questions... like someone said "you're only as good as the questions you ask."

Brad