Thread: Show me your lightweight rifle

Originally Posted by Lucky

man those things are light , the short 308 is awesome

I'm sure there's more in the tank with the 130s too

Originally Posted by Gibo

I'm sure there's more in the tank with the 130s too

not really ...... only 48.5g of ADI2206H
The secret to keeping velocity up in short barrels is to use a powder that burns completely inside the barrel.
If I'd stuck with 2209, half of it would be wasted as muzzle flash outside the barrel.

Originally Posted by NIMROD

not really ...... only 48.5g of ADI2206H
The secret to keeping velocity up in short barrels is to use a powder that burns completely inside the barrel.
If I'd stuck with 2209, half of it would be wasted as muzzle flash outside the barrel.

Have you tried?

Originally Posted by Gibo

Have you tried?

Yeah, I think mine was around 3000fps with h335.


Sent from my iPhone using Tapatalk

Originally Posted by MSL

Yeah, I think mine was around 3000fps with h335.


Sent from my iPhone using Tapatalk

I was getting 2995fps with 125gh Accubonds and H335. 16" barrel though.

Originally Posted by NIMROD

The secret to keeping velocity up in short barrels is to use a powder that burns completely inside the barrel.
If I'd stuck with 2209, half of it would be wasted as muzzle flash outside the barrel.

Thats a bit of an old wives tale really & if anything the opposite is true, the fastest velocity will always be achieved by compressing the slowest burning powder you can fit into a given cartridge. If you can select a slower powder that just barely gets you to your maximum pressure with a very full / compressed load, its always going to have better velocity than a faster burn rate powder that doesnt fill the case entirely. Think of it as the projectile getting a short sharp push with the faster burning powder, vs a push that has the same peak force but lasts longer with the slower burning powder. Even with a very short barrel the principal remains the same as the majority of the combustion process/peak pressure happens in the first couple of inches of barrel.

Your 130gr barnes/2206h combination would still need the best part of 30 inches of barrel to be burning the powder charge in its entirety before the muzzle. Peak combustion pressure has a far bigger impact on how fast the charge will burn, drop the charge weight back a couple of grains and you will then need a much longer barrel to burn all the powder. As you go up in powder charge & pressure increases, so does the speed of combustion.

One of the main reasons 2209 would burn more powder after the muzzle in a short barrel isnt so much that its a slower burning powder (although it does have some effect certainly), but the fact that its more dense & you cant get enough in the case with that same 130gr projectile, so you cant achieve the same pressure & therefore burn speed as you would with 2206h. Without the peak pressure going as high, the powder charge burns much slower as a whole & you get the big flame show.

Very insightful thankyou 6.5 CRD...... How would that bigger muzzle flash affect the suppresser life ?
Sorry for highjacking the thread

Originally Posted by 6.5 CRD

Thats a bit of an old wives tale really & if anything the opposite is true, the fastest velocity will always be achieved by compressing the slowest burning powder you can fit into a given cartridge. If you can select a slower powder that just barely gets you to your maximum pressure with a very full / compressed load, its always going to have better velocity than a faster burn rate powder that doesnt fill the case entirely. Think of it as the projectile getting a short sharp push with the faster burning powder, vs a push that has the same peak force but lasts longer with the slower burning powder. Even with a very short barrel the principal remains the same as the majority of the combustion process/peak pressure happens in the first couple of inches of barrel.

Your 130gr barnes/2206h combination would still need the best part of 30 inches of barrel to be burning the powder charge in its entirety before the muzzle. Peak combustion pressure has a far bigger impact on how fast the charge will burn, drop the charge weight back a couple of grains and you will then need a much longer barrel to burn all the powder. As you go up in powder charge & pressure increases, so does the speed of combustion.

One of the main reasons 2209 would burn more powder after the muzzle in a short barrel isnt so much that its a slower burning powder (although it does have some effect certainly), but the fact that its more dense & you cant get enough in the case with that same 130gr projectile, so you cant achieve the same pressure & therefore burn speed as you would with 2206h. Without the peak pressure going as high, the powder charge burns much slower as a whole & you get the big flame show.

These ideas never die. Here we are 10 years ago on the same topic.
https://www.nzhuntingandshooting.co....eve-not-13836/