A great deal depends on the gun itself and the types of loads used. Blanket statements like "Each inch costs XX feet per second" just don't cut it. As far as the gun goes, I've found cylinder gap to be the single most influential factor in revolver velocity. I have tested several 2 to 2.75" snubbies with tight gaps that were faster over the chronograph than 4" guns with big gaps using ammo from the same box. Whenever I seriously go wheelgun shopping I always carry a feeler gauge. My personal limit is .006" on a rare model, .004" on more common guns.
As far as ammo goes, it's been my experience that loads using heavier bullets will generally lose less velocity from a snubbie than lightweights. The type of powder being used also has a great deal of impact. For example, my long-time carry round in .357 Magnum snubbies has been Remington's 125-grain "Medium Velocity" load. It uses faster powders than the full-power offerings. Chronographed through several
snubbies the Medium Velocity load nearly matches and on one occasion exceeded full-power 125's in the same guns. The full-power loads really don't start to strut their stuff until fired from at least a 4" gun.
For your .38 and .44 Special loads I'd try powders like Unique or Universal for starters. Using lead bullets will also help keep your velocities as high as possible.
Thanks, Bill. From the vast spread in the data that is in Speer there are other factors than barrel length at work, and cylinder gap is most likely a big one. I frequently load Unique and have been looking at it with 200 gr copper plated lead bullets in the .44 S&W spl. I will try the Unique with copper plated lead in the .38 spl as well. Powder burning rate also has to be a factor and pehaps crimping style as well. I'm still hoping someone will be able to refer me to some published data, warts and all.
I worked exrtensively on this with a 2" 44 Special and learned a lot. For any given cylinder gap, you can maximize energy by EITHER using heavy lead or very light fragmentation bullets.
In the 44 Special, a 240 gr lead bullet and Blue Dot got 950 fps at safe pressures - powders in the Unique and Universal burn rate zone will jump pressures very fast with the deep seating depth of the 240s and slower than Blue Dot will just dump pressure out the end of the bbl.
For defense work, the 115 gr X-ploders from Shell Reloading (602) 983-7078 are very good - try 1550 fps using Green Dot!! This is over 600 fp of energy from a 2" bbl with moderate recoil.
When I carry this gun I have the X-ploders in the first 3 cylinders and the 240 gr lead rounds in the last 2. This gives 3 for quick close range defense and 2 for longer range or big penetration if needed.
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