anybody have good load data for 16" barrels?

[skyugo]

seems like a lot of loads are based on 20".

you'd reach a point of diminishing returns with a 16 I'd think...

so couldn't you use a bit less powder in a 16" and get the same performance as a larger powder charge?

[jmart]

No. Just use the same data. Figure 30-40 fps less velocity/inch or reduced barrel length. so a 16" will yield 120-160 fps less. That's ballpark.

[skyugo]

No. Just use the same data. Figure 30-40 fps less velocity/inch or reduced barrel length. so a 16" will yield 120-160 fps less. That's ballpark.

so basically any standard load will burn for 20" whether the bullet is in the barrel or not?

seems like there's some room for improvement...

[jmart]

I'm not sure I understand your question.

The 20" barrel gives added velocity, simply because the gas is contained in the longer barrel so it gives additional ooomph for a bit more time. This is pretty basic.

Powders that work in 20" also work fine in 16", for similar bullet weights, i.e., the same slow powders that work best for 75/77 grainers are appropriate for either barrel and the same powders that work best for 55/62 grainers are also appropriate for either barrel.

A general rule of thumb is 25-50 fps/inch of barrel, depending upon the
expansion ratio. .223 is moderate expansion ratio, so 35 fps/inch is a reasonable number. Something like a 45-70 (big expansion ratio) has less velocity loss/inch, something like a 22-250 (small expansion ratio), shows bigger delta's/inch.

The powders burn completely (or damn near completely), but the gas is still pressurized as the bullet exits the muzzle. What you see in muzzle flash is not unburned powder, it's the gasses being exposed to oxygen. Powder selection is based on burn rate and pressure curves for the gas system. While you may think a quicker powder is best (burns completely, less residual gas at the muzzle), it may not be compatible with the gas system/port location to cycle the weapon. Same thing with a too slow powder, there's narrow range of burn rate that dictates what works in an AR, and it's more a function of gas port location and bullet weight than barrel length.

[markm]

so couldn't you use a bit less powder in a 16" and get the same performance as a larger powder charge?

No offense, but that question is frightening. I hope you're not really assembling ammunition if that is the extent of your knowledge on the subject.

[skyugo]

No offense, but that question is frightening. I hope you're not really assembling ammunition if that is the extent of your knowledge on the subject.

i go by my sierra manual for loads... and if i have some crazy idea, i ask lots of smarter people questions first.

by that question i mean basically that you'd reach a point of diminishing returns faster on a short barrel. it seems i'm totally wrong on that account though.

[skyugo]

I'm not sure I understand your question.

The 20" barrel gives added velocity, simply because the gas is contained in the longer barrel so it gives additional ooomph for a bit more time. This is pretty basic.

Powders that work in 20" also work fine in 16", for similar bullet weights, i.e., the same slow powders that work best for 75/77 grainers are appropriate for either barrel and the same powders that work best for 55/62 grainers are also appropriate for either barrel.

A general rule of thumb is 25-50 fps/inch of barrel, depending upon the
expansion ratio. .223 is moderate expansion ratio, so 35 fps/inch is a reasonable number. Something like a 45-70 (big expansion ratio) has less velocity loss/inch, something like a 22-250 (small expansion ratio), shows bigger delta's/inch.

The powders burn completely (or damn near completely), but the gas is still pressurized as the bullet exits the muzzle. What you see in muzzle flash is not unburned powder, it's the gasses being exposed to oxygen. Powder selection is based on burn rate and pressure curves for the gas system. While you may think a quicker powder is best (burns completely, less residual gas at the muzzle), it may not be compatible with the gas system/port location to cycle the weapon. Same thing with a too slow powder, there's narrow range of burn rate that dictates what works in an AR, and it's more a function of gas port location and bullet weight than barrel length.

i think that answers my question. thanks.

[toddackerman]

To answer your question...

I have loaded 27 gns. of WW748 behind a 55 Gn. FMJBT w/c, WW SRP's and Mil. cases for years with great success, but it is a little on the "Warm" side, but definitely on the charts. It also is a very accurate load.

I wanted to find a powder that would perform as well for CQB loads,and use lighter charges to save wear and tear on the weapon, and reduce costs. I have decided to start loading 24 gns. of RAMSHOT Tac with the same 55 gn. bullet.

To me, 99% of what I do is within 50 yds., so as long as the weapon cycles, it's good enough for training.

As always....start at about 10% less than any suggested load and work up looking for signs of pressure.

[skyugo]

To answer your question...

I have loaded 27 gns. of WW748 behind a 55 Gn. FMJBT w/c, WW SRP's and Mil. cases for years with great success, but it is a little on the "Warm" side, but definitely on the charts. It also is a very accurate load.

I wanted to find a powder that would perform as well for CQB loads,and use lighter charges to save wear and tear on the weapon, and reduce costs. I have decided to start loading 24 gns. of RAMSHOT Tac with the same 55 gn. bullet.

To me, 99% of what I do is within 50 yds., so as long as the weapon cycles, it's good enough for training.

As always....start at about 10% less than any suggested load and work up looking for signs of pressure.

yeah i'm shooting 100 yards max right now. so i've been using sierra's 2900 FPS loads for IMR 3031 (22.8gr) or IMR4320 (24.9gr) cycles the rifle perfectly, and seems to be very easy on the brass as well.

basically for a short barrel you're saying you've gotta use a lot of powder to get performance. makes perfect sense.

I'll have to borrow a chrono sometime... see what i'm getting for actual velocity... probably 2650-ish?

[toddackerman]

yeah i'm shooting 100 yards max right now. so i've been using sierra's 2900 FPS loads for IMR 3031 (22.8gr) or IMR4320 (24.9gr) cycles the rifle perfectly, and seems to be very easy on the brass as well.

basically for a short barrel you're saying you've gotta use a lot of powder to get performance. makes perfect sense.

I'll have to borrow a chrono sometime... see what i'm getting for actual velocity... probably 2650-ish?

No you don't have to use a lot of powder to get performance. Mid range loads will shoot sub MOA if you do your job from a 16" barrel.