Top Ad

Collapse

Announcement

Collapse
No announcement yet.

How many RPM's is a bullet rotating fired out of a barrel with a 1:10 twist at 2700fps ? I came up with 3240 times per second or

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • How many RPM's is a bullet rotating fired out of a barrel with a 1:10 twist at 2700fps ? I came up with 3240 times per second or

    How many RPM's is a bullet rotating fired out of a barrel with a 1:10 twist at 2700fps ? I came up with 3240 times per second or 194,400 PPM's am i correct?

  • #2
    I come up with the same numbers. 2700fps X 12" = 32,400 ips divided by 10" = 3240 rps X 60 = 194,400 rpm.
    I do not have the formula for this, so I'm using common analysis and everyday math skills.
    I hope we're right.

    Comment


    • #3
      Close enough. Anything you hit with said bullet will not care about the rpms.

      Comment


      • #4
        Ditto~99 +1

        Close Enough.

        Comment


        • #5
          No wonder the old .223 rifles with 1:9 twist would not stabilize the heavy bullets. I did a comparison and it takes 16% more revolutions to stabilize a 75gr in 1:7 twist over the 55gr in the 1:9 twist. I had a rifle with the 1:9 and it would keyhole the heavy ones.
          The difference in the example is 705 feet per second increase in revolution for the 75gr. Just curious.

          Comment


          • #6
            Also, at a lower velocity, the heavier bullets would have a slower rpm twist.

            Comment


            • #7
              99explorer
              the example i used was
              55gr 3200 velocity 1-9 twist revs per second 4266
              75gr 2900 velocity 1-7 twist revs per second 4971

              Comment


              • #8
                The math checks out, without rounding up for fractional differences.
                Can we assume the 1-7 twist at 2900fps stabilizes the 75-grain .223 bullet?
                I have a friend with the same problem.

                Comment


                • #9
                  i used 75gr in the example, heaviest i have loaded is 62gr and they shoot fine.

                  Comment

                  Welcome!

                  Collapse

                  Welcome to Field and Streams's Answers section. Here you will find hunting, fishing, and survival tips from the editors of Field and Stream, as well as recommendations from readers like yourself.

                  If this is your first visit, be sure to check out the FAQ for information on posting and navigating the forums.

                  And don't forget to check out the latest reviews on guns and outdoor gear on fieldandstream.com.

                  Right Rail 1

                  Collapse

                  Top Active Users

                  Collapse

                  There are no top active users.

                  Right Rail 2

                  Collapse

                  Latest Topics

                  Collapse

                  • Reply to Fawns
                    by FirstBubba
                    Fawning season and "leaf" season pretty much coincide here. By the time does start dropping fawns, the trees and understory have leafed out...
                    Today, 11:01 AM
                  • Fawns
                    by MattM37
                    How's your local herd doing? Around here I seldom see many fawns in May, but everything seems to be a couple-three weeks ahead of schedule and we'll...
                    Yesterday, 07:21 PM
                  • Reply to The Constitution or The Big Lie?
                    by rock rat
                    Better Lab.

                    I agree that it's hypocritical to get upset over Jan 6 but not the summer of 2020. There were differences though. Floyd riots...
                    Today, 11:00 AM
                  • The Constitution or The Big Lie?
                    by rock rat
                    We've had almost 250 years of a peaceful transition of power. Our constitution is mostly about how we elect and who can be elected or appointed to the...
                    05-22-2022, 07:24 AM
                  • Reply to Georgia Primary (this one looks to be fun)
                    by jhjimbo
                    What are you talking about?
                    Today, 10:57 AM

                  Right Rail 3

                  Collapse

                  Footer Ad

                  Collapse
                  Working...
                  X