SIGforum.com    Main Page  Hop To Forum Categories  Ammunition    Terminal performance max range determinations for 5.56 hunting/defense loads
Page 1 2 
Go
New
Find
Notify
Tools
Reply
  
Terminal performance max range determinations for 5.56 hunting/defense loads Login/Join 
Freethinker
Picture of sigfreund
posted Hide Post
I’m not sure how much it’s generally accepted, but there is a criticism of just firing bullets at lower muzzle velocities with short range testing media to determine the bullets’ performance at distance.

The criticism points out that the spin rate of a bullet is determined by two things: the rifling twist rate and the bullet’s velocity. When a bullet is fired at a higher initial velocity its spin rate at long distance is higher than if it’s fired with a reduced, lower muzzle velocity load. That’s because the spin rate decays more slowly than velocity, and therefore high and lower initial velocity conditions aren’t exactly the same.

As far as I know, the question of whether spin rate upon impact affects wounding effects hasn’t been rigorously determined, but I do know that the question has been raised and that some shooters are therefore distrustful of simply reducing muzzle velocity to determine how bullets will perform at long distance velocities.

In any event, if I were really concerned about the matter, I would do my own experiments with handloads and the media that’s available. Even though something like Clear Ballistics test media isn’t a very good way of determining post-impact wounding effects, it can be used for a degree of comparison purposes by examining the permanent stretch marks. But another cheap and easy thing to try is to use soaked newsprint (newspapers). That’s probably even less realistic as a test medium, but it has one advantage in that the expansion cavities that are formed in the material are more or less permanent. They shouldn’t be evaluated as absolutes, but they can be used to compare the performance of one shot to another.

The method is to take a stack of newspapers (10-12 inches or more), loosely bind them together with sturdy, waterproof tape, and immerse it in water for several hours. (Binding loosely is necessary to allow for the stack’s expansion and to permit the water to soak the interior.)

Set up stacks at different distances and shoot them with your preferred load. Open the stacks and see what things look like inside, especially the differences between a close range shot and one at distance. Also which one penetrates farther? (For a complete answer, more than 12" of dry paper may be necessary.) I try to shoot relatively soon after the stack is removed from the water.

I’ve done a little of that sort of thing, and although I readily admit the medium is far from perfect, I was able to determine, for example, which 223 bullets were more likely fragment and penetrate less than others. I can’t, of course, guarantee that any of that will reveal what you’re interested in, but as I say, it’s cheap and relatively easy. Even if you don’t have a ready source of actual newspaper paper, “blank newsprint paper” is available from a variety of sources, including Amazon.




6.4/93.6

“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 47270 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Experienced Slacker
posted Hide Post
True regarding spin rates. I hadn't accounted for that.
Also, I was apparently not reading well, and ignorant of youtube content. Sorry.
 
Posts: 7472 | Registered: May 12, 2004Reply With QuoteReport This Post
  Powered by Social Strata Page 1 2  
 

SIGforum.com    Main Page  Hop To Forum Categories  Ammunition    Terminal performance max range determinations for 5.56 hunting/defense loads

© SIGforum 2024