school me pls , How we can have a batter performance ?

[Chatrbaz84]

My question is to understand the relation in between
bullet weight , powder burn rate and temperature with the most performance and the highest velocity in multi purpose application with the shortest barrel is possible.

example ,:
lets say building a precision tactical rifle for hunting as well 18 inch short 308
and 556 AR pistol platform for all purposes

my goal is to understand what bullet weight and what type of powder and how much give the best performance(accuracy and volatility) in a shortest legal barrel is possible(556 AR Canadian restricted law 5-7 inch , 308 Canadian non restricted law 18 inch custom barrel not factory)

any though?

 

[Maple57]

Your question is vague, so I will be as well.

Short barrels require fast burning powders to completely burn before the bullet leaves the muzzle.

A longer barrel allows you to run slower powders.

You can run fast powders with heavy bullets as long as the load is developed that way, but velocity will be slow.

The cartridge case is generally most efficient when full or close to full, but that does not mean you fill any case with any powder.

If you want to run a short barrel and get some decent efficiency, then focus on light bullets with faster powders.

If a guy wants a long range rifle, the reverse is true. He will focus on slower burning powders and heavy projectiles with a long barrel.

Also, the barrel twist rate should be selected based on your anticipated velocity and bullet length.

It's important to pair the spin rate with the load. Since your velocity will be low, (due to short barrel) your twist rate should be fast.

 

[Suther]

I find club soda makes for a good batter. Or beer.

 

[Djb1]

We am make boolit go zoom zoom

 

[mareshow]

In most cases for rifle calibers, the shorter the barrel the less powder is burnt behind the bullet in the barrel instead of out of it (read cool flame thrower happening). Generally this is reflected in velocity loss. Typically most agree that its around 50 fps per inch of barrel lost. There's actually some tests out there where a guy cuts an inch off the barrel at a time and shoots some groups. there's some sweet spots for length for all of them. 308 is right around 20" if you want a shorter barrel, 6.5 CM is 22". 300 win mag actually saw a velocity increase at about 26" over 28" which I thought was interesting.

Long story short (pun intended). Shorter barrels do have their merit and some would argue more accurate due to less barrel whip and harmonics. I myself have a 20" 308 that I am quite happy with. That said velocity is king when reaching out to distance as the more you have the less time there is for wind to affect the projectile as well as less drop meaning you can go longer distances. So in your case if you don't take hunting shots further than 300m, a 16" or 18" compact 308 would do quite nicely, But do understand that for longer shots (400m or more) wind will become a much larger variable on whether you take the shot or not. My 308 sees ranges of 500m all the time comfortably but at 700 m, I have to pay much closer attention to the wind. if going with a shorter barrel, understand that a medium burn powder for your caliber would be preferred over a really fast one vs a slower one. Oh and prepare for a flame thrower.

but to answer your question for a non restricted bolt gun, you can have whatever barrel length you want provided the overall length is not less than 26". Just understand that your range will be affected.

For a 223 the same principal is applied. If you're building a fun range gun with no purpose other than making loud booms. then go as short as you want and watch for flames, if building something with a purpose say to 300m (common range length) I wouldn't go shorter than say 12", 10" or 8" would work too but no real point unless its a PDW or range plinker

 

[owlowl]

My question is to understand the relation in between
bullet weight , powder burn rate and temperature with the most performance and the highest velocity in multi purpose application with the shortest barrel is possible.

example ,:
lets say building a precision tactical rifle for hunting as well 18 inch short 308
and 556 AR pistol platform for all purposes

my goal is to understand what bullet weight and what type of powder and how much give the best performance(accuracy and volatility) in a shortest legal barrel is possible(556 AR Canadian restricted law 5-7 inch , 308 Canadian non restricted law 18 inch custom barrel not factory)

any though?

The most performance vs average factory performance for a 18 inch 308 is practically negligible at all ranges you should really expect from 18 inch 308 to perform. No matter how magical you powder + bullet + twist combination might be, 308 18 inch barrel is a short range rifle. Like it or not. At short ranges (300 and under) the difference between most average factory loading and you uber custom hand loads will be close to none for any practical purpose. Would you see a difference in numbers, like velocity and group size? yes, would that make any difference on a real target? No.

If you look at some test results, for instance:

https://rifleshooter.com/2014/12/30...ato-barrel-length-versus-velocity-28-to-16-5/

You might see that bullet weight changes velocities greater than barrel length. 147 gr from 18 inch barrel leaves at 2739 ft/s, 180gr at 2411 ft/s. To push 180gr at 2700 ft/s you would need over 28 inch barrel. If you are after velocity - you have no real choice but lightest bullets possible. Would that matter more than extra energy from 180 gr under 50 yards? Probably not, but everything is a tradeoff. If you really want max performance at longer ranges 18 inch 308 is not that anyway, so why would you even sweat so much about it.

Moreover, no one can really tell you what your specific rifle would like at the end of the day. You might get better group with 150gr or 168 or this powder or that powder, you would have to try it for the specific rifle anyway. But again, if you really care about tightest possible group with highest possible performance 18 inch 308 is not it. In fact the less you get obsessed with performance numbers and more obsessed with your own skill of shooting your rifle in a real conditions the better you will be. This bench rest game of numbers requires different toys all together.

 

[209jones]

Another example is the military developing the SBR type guns for good handling in CQB, not as a sniper rifle. Look at what they are playing with in the US, in the NGSW program. A 223 or 308 can shoot "accurately" to 500 yds +, but, that also depends on your definition of accuracy required, at what range, your skill level and conditions. Some PRS guys like 20" bbls for handling, they usually get a heavier contour to stiffen it. The "unburnt" powder is still making expanding gases when it comes out, so, you aren't really wasting it in a shorter barrel, until you get to a powder slow enough to have actual unburnt kernels blown out, and the normal powders for a 223 or 308 don't normally do that, they're usually completely burnt by the time they hit 14-15". You need to assess what you really want the guns to do for you in practical usage, no one gun will do it all for you. And as others have said, you will be settling for a compromise one way or the other, speed and flat shooting under 300 yds, or speed and a bullet that doesn't perform as well ballistically, past 300yds, or a slower speed with a heavier bullet, that just needs a bit more skill to use at longer ranges, but has fairly reliable ballistics.