1/7 or 1/8?

[shua713]

i am looking into building an ar. is there a big difference wether the barrell is 1/8 or 1/7? i was looking at the m4 chart and they are all 1/7, but i have found a lot of upper groups with barrells that are 1/8. also what are your thoughts on the quality of palmetto? i didn't see them on the chart at all.

[PappyM3]

The Army Marksmanship Unit puts 1/8 twist barrels on the Squad Designated Marksman M-16A4s that they build for some line units. They know their stuff and the rifles shoot pretty dang well. Although, the SDMs aren't really designed to be shooting tracers.

I would feel perfectly comfortable with either twist rate.

[philipeggo]

The way I use the chart is to read the descriptions of features and then apply that to what I wanna buy aka if it has a the things that i find desirable or necessary then ill buy it. The chart is a guide you can use on any purchase .


i am looking into building an ar. is there a big difference wether the barrell is 1/8 or 1/7? i was looking at the m4 chart and they are all 1/7, but i have found a lot of upper groups with barrells that are 1/8. also what are your thoughts on the quality of palmetto? i didn't see them on the chart at all.

[shua713]

thank you for your input. this helps clear things up a little bit. but brings me to the next question. would you want to use lighter bullets with a 1/8 barrell then you would with a 1/7 barrell?

[JasonM]

thank you for your input. this helps clear things up a little bit. but brings me to the next question. would you want to use lighter bullets with a 1/8 barrell then you would with a 1/7 barrell?

no.

twist rate and stability doesn't have anything to do with the weight of a bullet- the issue is the length of a bullet. Regardless of weight, longer bullets need a faster twist to be stabilized.

The tracer bullet that the 1:7 is needed for is a medium weight, but relatively long bullet. A 1:8 will be just fine with heavier but shorter bullets...

[0reo]

Does the twist rate affect terminal performance of the round on target? Would a 1/7 twist upset better / faster in gel then 1/8?

[nimdabew]

Does the twist rate affect terminal performance of the round on target? Would a 1/7 twist upset better / faster in gel then 1/8?

no and no