Whats the ruff numbers on a 77gn SMK out of a 18" 1/8 v/s a 77smk out of a 20" 1/8 tube? (AR15 platform)
18" barrel v/s 20" barrel - velocity for 223
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Re: 18" barrel v/s 20" barrel - velocity for 223
Could someone include numbers for the 24" tubes as well. Building a new varmint rig and was just about to post the same question.
Could someone include numbers for the 24" tubes as well. Building a new varmint rig and was just about to post the same question.
Re: 18" barrel v/s 20" barrel - velocity for 223
The muzzle velocity you get will greatly depend on your specific rifle, temperature, etc.... But, here are the specs Southwest Ammo is giving for their 5.56 77gr SMK loads from their group buy:
20" Barrel: 2800fps
18" Barrel: ~2725-2750fps
Bottom line is there really isn't a dramatic difference. I haven't had a chance to put my MK12 on a crono yet, so I can't give you my actual specs.
The muzzle velocity you get will greatly depend on your specific rifle, temperature, etc.... But, here are the specs Southwest Ammo is giving for their 5.56 77gr SMK loads from their group buy:
20" Barrel: 2800fps
18" Barrel: ~2725-2750fps
Bottom line is there really isn't a dramatic difference. I haven't had a chance to put my MK12 on a crono yet, so I can't give you my actual specs.
Re: 18" barrel v/s 20" barrel - velocity for 223
Based on my testing of my hand-loads, I see a 30-40fps increase from a 20" over a 18". The 20" has a 8 twist and the 18" has a 7 twist and I have heard some people suggest a faster twist reduces velocity (don't know if that is the case).
I see a 150fps increase going from 14.5" to 18", so the increase is more significant there.
Based on my testing of my hand-loads, I see a 30-40fps increase from a 20" over a 18". The 20" has a 8 twist and the 18" has a 7 twist and I have heard some people suggest a faster twist reduces velocity (don't know if that is the case).
I see a 150fps increase going from 14.5" to 18", so the increase is more significant there.
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