[Chum]

Clayshooter

Where did you get the .17 info that goes to 24"? I have looked at Bullberry's page and they have data up to 22". And what you said is correct about 16" being the length of highest velocity of the .22lr. It does vary a bit depending on ammo. But if the charts I have looked at are correct the bullet slows after 16" but accelerates back up to very close the same velocity at 24". It's like a double burn rate. I have no clue on what this does for shotguns but the longer barrel defintly helps for sighting. The thing we are trying to plot out is the .22 magnum loads in particular. I can't find any charts that are .22 magnum specific. The .17 is different than the .22lr being optimum at 18-19" so I would have to say the magnum could also be.

The "crack" of a gunshot is the bullet breaking the sound barrier as you said. There are airguns that will do this nowadays. Is that a word? Whether the bullet does it inside or outside the barrel plays a major role in noise level and accuracy. Thats one reason for different velocities of .22lr ammo and one of the main reason for barrels being longer then 16" It gives the bullet time to recover from the effects of breaking the sound barrier. You don't want the loud crack when shooting a .22lr because that means the bullet broke the barrier outside the barrel. Very interesting stuff. If you look up a few posts you will see where I posted a link to a website that has a chart down the page. There is tons of other info.

 

[Clayshooter]

velocity

Thanks for the correction on the 22 vs 24" barrel length. I think I was looking at your exact reference before and found it at Al's Varmint something. The point about inside or outside the barrel is a new one to me. Do I get this right? Are you saying that in a 22 rimfire that the peak velocity is achieved at 16' and then the peak repeats itself again at 24"? Or are you saying that below 16" the velocity really drops quickly, but between 16" and 24 it continues to increase in velocity until 24 inches?

On the 17 HMR vs the 22 Mag I would dare bet a full can of soda that the 17's burn rate would be different than the 22 Mag. My best guess senario comes from the fact that the 17 is reloaded with a relative new powder called little gun (sp?) and the Mag has been around longer and probably has a much different style powder. Too bad that they both aren't reloadable (not really, because one of the attractions to the 17 HMR for me is that I don't have to reload for it). If you could reload them and loaded them both with the same burning rate of powder or the exact same powder, the parrallels between the two might be more similar. The above is not from experience, I can't refer to any publications backing this up, this is pure "Clay" conjecture. I will be glad to be set straight when you guys figure out the answer. Thanks for sharing - Clay

 

[Chum]

Clay

Thats the way I understand it by looking at those charts but the more I read about it the more I don't think it's correct. It seems to be the rule that .22 get a full burn at 16" The chart has alot of blank spots at 24" But the ones that are listed are in bold type. I guess I was invisioning a ca-boom theory. I'm going to have to pick up a good book on this.

 

[Clayshooter]

velocity

I play with a Oehler 35P and am interested in the mysteries of ballistics, I just don't seeing me cutting my 1710D Signature down and inch at a time to figure out the answer to what is the optimum velocity obtainable with a 22 rimfire barrel. Personally, I believe that we all spend too much time talking about shooting and we all would benefit from spending more time at the range with the weapon of your choice practicing basic shooting form and trigger control techniques.

I love this so much that I just have to move my mouth about this subject and when the guys at work get sick of my endless chatter about firearms I have to come home and check the web daily. I know that I need to get a life. I have to get to bed 4 AM comes early.

 

[Elkein]

Portugal Look at winchesters website, they have hundgun Vs rifle ballistics for some of their rimfire ammo. It seems they use a 6 inch revolver barrel though for most of it. rimfire ammo appears to loose 20-40 percent of it's power when fired out of revolvers. ( note that's not velocity. )