Loss of velocity 44 special in 44 mag chambers

[mickbr]

Its probably been asked a lot of times before but the search term is so long its difficult to get anything specific to come up :)
Thanks if anyone has data or even youtube vids relating to velocity difference of a 44 special case in a 44 special chamber vs same case in the 44 mag chamber. I know its not a world changing amount, just interested to know.

[Petrol & Powder]

The short answer is technically, No.

The case will expand to fit the walls of the chamber when fired and the nose of the bullet will enter the throat before the base of the bullet clears the casing.

The difference in length between the 44 Special chamber and the 44 mag chamber is shorter than the length of the driving bands of the bullet. The only additional volume appears after the base of the bullet reaches the beginning of the throat. At that point we're talking the volume of a "ring" that is the thickness of the brass casing and .125" long. While there is some additional volume in play, it's a tiny amount.

[tazman]

Any such difference would be small and very difficult, if not impossible to measure. Finding two handguns with the exact same cylinder size and barrel clearance, not to mention bore smoothness would be hard to do.
There is undoubtedly, more velocity difference due to inconsistencies in production than would come from the difference in chamber length.
As Petrol & Powder stated, the difference in volume is very small.
I ran tests with loads of my own in different length barrels and often found the barrel length often didn't make a lot of difference. In one instance, with a particular revolver with an 8 3/8 inch barrel, it normally tested slower than a 6 inch barrel with the same load.
Differences in individual guns matters a lot.

[Larry Gibson]

Years back when I had access to a couple 44 SPL revolvers and a couple similar 44 Magnum revolvers, all S&Ws, Chronographing the same 44 SPL loads in both [factory, Skeeter's load (429421/7.5 Unique) and 16 gr of 2400 under the 429421] produced essentially the same velocities given the variances test to test variation and the differences in the revolvers. The 44 magnum revolvers did give, within a few FPS, consistently higher velocity with the 16 gr 2400 load. This was assumed to be because while the revolvers had the same barrel lengths (4") the Magnum revolvers had the slightly longer cylinder/barrel length.

BTW; those four S&Ws were tested using a Ransom Rest with the target at 50 yards. We found essentially the accuracy of the 44 SPL loads fired in the 44 Magnum revolvers was also essentially the same as when fired in the 44 SPL revolvers.

[Wally]

I have a 6.5" M-24 and a 7.5" Ruger SBHK. Shooting .44 Spls in both, I find the Ruger is more accurate. The cylinder throats in the M-24 are larger than .431"; in the Ruger they are at .4295".