Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Site Notices
Posted: 5/20/2003 6:07:51 PM EDT
Hello, would a 16" rifle with a 1 in 7 twist shoot the 69,72,75 and 77 grain bullets better than a 20" 1 in 9 twist? Thanks
Link Posted: 5/21/2003 12:59:48 PM EDT
A 20" 1/9 may or may not work with the 75 & 77gr. It does in some people's guns, it doesn't in others (like mine). It'll work fine with the 69gr and probably with the 73gr. The 16" 1/7 will work fine with all of them.
Link Posted: 5/21/2003 1:36:50 PM EDT
[url]ammo-oracle.com[/url]
Link Posted: 5/21/2003 2:10:27 PM EDT
If your just looking to throw em all downrange get the 1/7, but if you want accuracy there are better twists out there.
Link Posted: 5/21/2003 2:48:03 PM EDT
Originally Posted By Jetlag: If your just looking to throw em all downrange get the 1/7, but if you want accuracy there are better twists out there.
View Quote
Please explain this comment to all the people getting sub .5 MOA from those rounds and using that twist please.
Link Posted: 5/21/2003 3:10:59 PM EDT
So, that ammo page says that a 1:9 twist will stabalize a 40-75 grain bullet with a lead core. But if the bullet is steel it is longer for the same weight and a 62 grain steel bullet is as long as a 75 grain lead core.
Link Posted: 5/21/2003 5:01:23 PM EDT
Its more complicated than that for example the 77 grain ammo is shorter than the 75 grain ammo due to the more taperd shape of the 75 grain ammo and there are air pockets at the tips of those bullets too. A 1/7 twist 16" barrel will stabilize a 75 grain bullet better than a 20" 1/9 twist. I think that answers your question. The 1/9 stabilizing the 75 grain round is a lie perpetuated by Bushmaster so they wont have to switch to the 1/7 twist. It will stabilize a 69 grain bullet in every barrel lenght though.
Link Posted: 5/21/2003 6:11:35 PM EDT
Originally Posted By DevL:
Originally Posted By Jetlag: If your just looking to throw em all downrange get the 1/7, but if you want accuracy there are better twists out there.
View Quote
Please explain this comment to all the people getting sub .5 MOA from those rounds and using that twist please.
View Quote
1/7 may work fine but it spins the bullets faster than necessary, which is not a good thing.
Link Posted: 5/21/2003 7:17:31 PM EDT
Originally Posted By Jetlag: 1/7 may work fine but it spins the bullets faster than necessary, which is not a good thing.
View Quote
Not trying to be a smart ass, but why is it not a good thing if the 1/7 is getting .5 MOA? What difference does it matter how fast it's spinning make if it's producing those kinds of results?
Link Posted: 5/22/2003 7:12:01 AM EDT
I certainly would not encourage someone who is achieving such accuracy to dump their setup, but when someone is starting fresh why not pick a twist closer to what is optimal? A bullet spun too fast is less accurate than a bullet spun just right, that's just the way it is.
Link Posted: 5/22/2003 10:19:44 AM EDT
[Last Edit: 5/22/2003 11:18:21 AM EDT by Yojimbo]
I guess it boils down to whatever you find as accepatble combat accuracy. To me a 1/7 shooting .5 MOA is probably even 4 to 6 times better than what I feel would be acceptable in a combat carbine. So I would say it more than meets the requirements. I really don't believe a .25 MOA accuracy difference or whatever will be missed in a combat situation.
Link Posted: 5/22/2003 10:50:03 AM EDT
So jetlag what twist would you suggest for 75 grain ammo if not a 1/7?
Link Posted: 5/22/2003 11:39:00 AM EDT
1/8. Looking back at what I originally said "if you want accuracy", that seems to imply you would get inaccuracy out of a 1/7, and that was definitely not my intention. The question was pretty vague. To come up with a concrete answer a lot questions still need to be answered. What rifle? What chambering? Factory ammo or hand loads? Velocity? At what distance? Air density? Seriously. Some are implied, some are not. We can take educated guesses and give a general answer, as I did. But I simply did not want to leave it at that, so I mentioned there are better twists for that range of bullets, and there are. There are no simple answers and I didn't want it to appear as though there were.
Link Posted: 5/22/2003 11:55:11 AM EDT
can a 1/8 do what the 1/7 can?
Link Posted: 5/22/2003 12:11:57 PM EDT
I thik jetlag was implying a 1/7 twist would over stabilize the bullet at long ranges. Then again the shorter the barrel the lower the velocities and the slower the RPMs so a .223 pressure loaded 75 grain round from a 16" barrel would have less RPMs and be less over stabilized than a 20" barreled 1/7 twist rifle firing 5.56 pressure ammo. The 1/8 twist is great for longer barrels but I dont think he will be giving up anything using the 16" barrel and 1/7 twist. I am pretty sure "if your just looking to throw em all downrange get a 1/7" implies a lack of accuracy though. [;)]
Link Posted: 5/22/2003 12:16:25 PM EDT
Originally Posted By FMJ: can a 1/8 do what the 1/7 can?
View Quote
In regards to...? M856 and 100+gr bullets? They are better off used through a 1/7.
Top Top