QuickLoad questions - revolver barrel length, and porting

[Navy_Guns]

In the program QuickLoad, the software makes no distinction between rifles, semi-auto pistols, and revolvers. As such, it handles barrel length the same for all three - the length is the distance from the breech face to the muzzle.

However, I have a Taurus 450-SS-UL with a "2 inch barrel" according to Taurus that really measures 3.81 inches from the muzzle to the breech face. The length of the barrel (back of forcing cone to the muzzle) measures 2.16 inches. Is it the norm for manufacturers to report revolver barrel length differently from the standard used on rifles and shotguns? When using QuickLoad, I should enter my barrel length as 3.81 inches, right?

Lastly, the final 0.665 inches of the barrel is ported with six holes measuring 0.135 inches in diameter. For when the end of a barrel is ported, especially in a barrel that's short to begin with, is there a "rule of thumb" for how much velocity loss you realize? Of course I could chronograph a load and compare it to the QuickLoad prediction to find out, but somebody HAS to have dealt with this already, right?

 

[243winxb]

deleted, but this might be of interest. http://www.thehighroad.org/showthread.php?t=537410

 

[Navy_Guns]

But in QuickLoad, it uses cartridge overall length, case length, bullet length, and bullet seating depth to calculate bullet travel. If you enter a barrel length of 2 inches, it calculates that your bullet travel is about an inch. I don't think that is accurate.

 

[243winxb]

Deleted wrong info. Navey Guns had it correct , thank you Steve for explaining it. Pays to read instruction.

 

[srsmith]

From the QL 3.6 manual page 62: Barrel length is measured from the bolt face to muzzle. Look at the QL plot of pressure vs barrel length and you will see that the bullet starts not at zero, but at it's position in the loaded catrtridge.
Be sure the gun is unloaded, push a thin dowel into the muzzle until it stops and mark at the muzzle. That is the barrel length for QL.
Since revolvers "leak", the QL models for revolvers usually overestimates the muzzle velocity.

Be Safe and have Fun
-steve

 

[Navy_Guns]

The next interesting quest will be to see how much further loss I realize from the porting (over the cylinder gap loss). I'd think if you entered the barrel length as ending just at the start of porting, you'd under-predict velocity. Enter the full length and you over-predict. The point between the two won't be huge since the ported length is only .665", but it's an itch I've got to now scratch.