Muzzle Velocity 4" barrel vs 5" Barrel

[Shuey134]

I'm getting ready to begin reloading .40 cal ammo for my Beretta 90-two. Most of the load information I find has been tested with a 4" barrel, what muzzle velocity can I expect out of a 5" barrel? Will the bullet be traveling faster or slower. Obviously I would need to confirm with a chronograph, but I was just looking for some preliminary data to get started with.

Thanks

[knight0334]

Generally the MV varies 25-100fps per inch. Other factors is burn rate of powders, powder charges, etc.

But for the most part you can average 40-80fps per inch increase of barrel upto about 24 or 26 inches of barrel for rifle cartridges and for handgun cartridges the gain drops off after 16-22" of barrel. The gain after 26" for rifles isn't as great unless you have "magnum" or an "overbore" cartridge like the .220 Swift, 45-120, or something that has more powder than it can burn in a shorter barrel.. The gain for pistol cartridges drops off fast after the 16-20" of barrel, sometimes loosing speed within the barrel.

Figure 40-80fps more velocity between a 4" and a 5" unvented/nonrevolver barrel.

[Bama Man]

ditto at what Knight says.

[GRIZ]

All of what is said is true. However, due even though both barrels were made by the same manufacturer there are variances in bore size, chamber dimensions, barrel wear, and other factors you may find the velocity is higher out of a 4".

I tried this with a Glock 17 and 19. The 19 was running about 50-75 fps with ammo out of thesame box. Tried different types of ammo and they chronographed 50-75 fps faster in the 19.