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1:8 Twist 308 Win

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nralifer View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nralifer Quote  Post ReplyReply Direct Link To This Post Topic: 1:8 Twist 308 Win
    Posted: February/11/2018 at 04:27
Testing this weekend a wild hair idea of chambering a 308 Win in an 8 twist 18 inch barrel to have a gun that has the power of a 3006 and can shoot subsonic and use a 6" suppressor.  So far I have gotten average 2947 fps using the 155 Palma bullet with WLRM primers and 49 gr  Leverevolution. The subsonic load is a 204 gr ICBM in front of 15 gr Trail Boss ignited with the WLRM primer generating an MV of 1081 fps.

Edited by nralifer - February/11/2018 at 04:40
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kickboxer Quote  Post ReplyReply Direct Link To This Post Posted: February/11/2018 at 07:27
Wow... outstanding.  You know, you are going to force me to start reloading again, yet...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: February/11/2018 at 12:58
2947fps out of a 18" 308Win barrel with a 155gr bullet?  

That's faster than is typical for a 24" barrel with 155gr bullets.

One of these days you will blow yourself up.  I've had a rifle blow up in my hands once and I did not enjoy that one bit.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SVT_Tactical Quote  Post ReplyReply Direct Link To This Post Posted: February/12/2018 at 07:30

I did the whole 308 subsonic thing for a bit.... 16" barrel, but found with the blackout now, not much reason to go load 308 sub rounds that aren't as constant as I liked when shooting subs.  a 30cal projectile fired at the same speeds will yield the same results if the same weights.... the blackout bolt gun does it better than the 308 bolt gun when it comes to subs....IMO


Loading the 308 to 30-06 levels you are going to blow something up, just a matter of when.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonoMT Quote  Post ReplyReply Direct Link To This Post Posted: February/13/2018 at 16:11
If I hear a loud boom to the east at least I'll know what it was.
Reaction time is a factor...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nralifer Quote  Post ReplyReply Direct Link To This Post Posted: February/15/2018 at 20:44
Well, guys don't worry. I have been using a similar load for a long time in my 10 twist 308.  The new rifle we tested was one that a friend of mine and I thought up. He sells actions for ARC. The gun has a Proof Research 8 twist and is 18" long. The load is Jason's 155 gr ICBM, with 50.5 grains of LVR using BR4 primers and Lapua small rifle primer loaded to a 2.880 COL. MV is 2960, and grouped 0.30" at 100 yds.  There was no primer flattening, no extraction problem, no enlargement of the primer pocket and no shiny spots on the brass.  The subsonic load was 12.7 gr Trail Boss using a 188 gr ICBM bullet at 1020 fps. It produced 0.5"groups at 100 yds and with 35MOA elevation one could hit a 10" gong 10/10 shots at 300 yds. on a windy day. The 204 gr ICBM did not shoot with consistent velocities I think because the bullet is long and compressed the TB powder which behaves erratically when compressed.  The gun shows the extreme versatility of the 308 Win with good bullets and a tight twist barrel.  The Leverevolution powder is an excellent one and is the reason we get such velocities with our bullets. The 155 gr ICBM and the 150 gr Bulldozer have a reduced bearing surface and when tested against other 150s on the market have a 50 fps advantage in MV.  That Proof Research barrel is one sweet tube. With a 6" suppressor the subsonic loads are quieter than a pellet gun. Fun stuff!! 

  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 338LAPUASLAP Quote  Post ReplyReply Direct Link To This Post Posted: February/22/2019 at 22:49
Interesting.
No one
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: February/25/2019 at 12:34
I triied both of those bullets in my 24" Proof carbon fiber sleeved barrel and I am getting about 3050fps with the 155gr ICBM Palma bullet and around 3100fps with the 150gr Bulldozer.

I still think George's 2950fps out of an 18" tube is a bit hot, but it is not as dangerous as I originally though.

Going to a faster twist rate is an interesting idea.  With the right bullet construction, faster twist will increase lethality.

I am looking at getting a Blackout with a 1 in 5" twist or faster if I can find one.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: February/25/2019 at 13:09
A 5" twist?  Curious about that one, fill us in. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: February/25/2019 at 15:50
Originally posted by supertool73 supertool73 wrote:

A 5" twist?  Curious about that one, fill us in. 

In due time.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Urimaginaryfrnd Quote  Post ReplyReply Direct Link To This Post Posted: February/25/2019 at 19:42
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SVT_Tactical Quote  Post ReplyReply Direct Link To This Post Posted: February/25/2019 at 20:53
Do any barrel makes offer a 5 twist in a 30cal tube? 
"Most folks are about as happy as they make their minds up to be" - Abraham Lincoln
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