Velocity Differance

[Jtcolter]

What is the difference in velocity for the LR with 1 5/8`` vs 1 1/8`` Barrel length?

[TwoGunJayne]

Simple answer: Minimal difference. The differences between ammunition and barrel length combos are all jumbled up until about 4" of barrel length. Some rounds will "win from the short barrel," some will "win from the long barrel." It might not even be the same round!

Real answer: Unfortunately, there is no simple answer. It even varies from build-to-build in the same revolver make. Your cylinder gap, your particular load, variances in that loading from even the same batch, from the same brand and maker, heck... from even the same box of ammo.

I've seen over 300 fps extreme spread variance within one box of ammo in one gun. My NAA Mini Master does this with Hornady Critical Defense .22 mag ammo from the same box. It's really complicated. The real answer is a range, a spread of numbers. There are, however, some "good ideas."

Compare a bunch of rounds in several different examples of the same make in both sizes? A graph of chrono results will show spikes and dips, it won't be a straight line. A spreadsheet (like free open-source LibreOffice) is invaluable for crunching the data and you can even make it spit out nice graphs.

The big issues are lot-to-lot variances in an ammo production and the characteristics of your piece  (or pieces) under test. A little cylinder gap change can make a big difference, so stats for my test guns probably won't agree with your test stats. Remember, to make a halfway decent measurement you must do it at least ten times. That would mean ten guns of the same make, plus something called "error analysis" and a total of 100 shots fired through a chrono. Error analysis math is one of the most difficult concepts to first grasp in physics, it's just alien if you've never seen it before. This is what you'd need to calculate the "best fit" line and that would give you a "single number answer." A real-world gun will show high or low near that number, error analysis gives you the "plus or minus X percent" information.

I'm just saying "it's hard, double hard, to give a definitive answer to your question."

Sorry, sir. There's quite a bit more to it than that. 

http://www.ballisticsbytheinch.com/
The "Ballistics by the inch" is a great place to start. They use a solid, non-gapped barrel for their tests. Expect slightly lower numbers through a revolver. It is a great place to start making a spreadsheet and pick your ammo to test from there.

I suggest starting with a spreadsheet, there is much published ballistics data. Unfortunately, it will most likely not be the same in whatever particular individual gun you have. A bigger than normal cylinder gap drops your velocity and can have a major effect.

[TwoGunJayne]

Sorry for the half-written post, forgot this was the FAQ section. I fixed it now. Carry on, gentlemen... 

Edit: Oh yeah, one more thing...

[G50AE]

Welcome to the forum Jtcolter, I hope TwogunJayne's rant did not run you off.

[Canoeal]

This will give it to you straight.

[OV-1D]

  I've always heard Superman is faster than a speeding bullet so just how fast is the quickest factory projectile on the market , not necessarily a 22 by the way ? Inquiring minds need to know .   

[Canoeal]

I am not really sure... but Friday @ the LGS they were talking about some rifle loads that were @ 4100 fps, and that made them flat shooters.

[barrytheprof]

What a great thread. This is the info I've been looking for for quite a while.

Thanks to all.

[Canoeal]

I googled it.  This was the answer:

The . 220 Swift remains the fastest commercial cartridge in the world, with a published velocity of 4,665 ft/s (1,422 m/s) using a 29 grain bullet and 42 grains of 3031 powder.

[Wumbey Goomba]

 

     4/8 difference

[Canoeal]

     4/8 difference