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Best twist rate for 7mm-08 with a short barrel?
#6503373
10/20/16 02:41 AM
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Joined: May 2012
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Burton Ranch
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I would like to build a 7mm-08 that can stabilize heavy bullets out of a 16" barrel. Does anyone have any experience with this? Thanks
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503415
10/20/16 02:58 AM
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TexFlip
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1:8.5" twist will work well with 168s. How heavy you wanna go?
Just to make sure that it is done thoroughly, I go both ways.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503422
10/20/16 03:04 AM
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ChadTRG42
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For the 162/168 grain, a 1:10" would be minimum and 1:9" would be best. For the 180 grain VLD's and Hybrid's, a 1:9" is minimum, and even a little faster would be better. For the new 195 EOL, a 1.83" is minimum, but a 1:8" is ideal. http://www.bergerbullets.com/twist-rate-calculator/
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503427
10/20/16 03:06 AM
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Gone to Texas
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503479
10/20/16 03:42 AM
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Burton Ranch
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Thanks, I was wondering if faster than 1:8 would be advisable? Is there such a thing as a twist that is too fast? 180 grn would prob be what I would be interested in. I would be running it with a can if that matters. A side question since you seem knowledgeable with the caliber. I have a ruger m77 hawkeye in 708. What would be the heaviest bullet you would push through it?
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503522
10/20/16 04:39 AM
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Joined: Sep 2009
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ChadTRG42
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If you look at the twist rate calculator link, you can run the numbers with the various twists and stability factors with various bullets. You want something over a 1.4 or a 1.5. For your Ruger, the 180's are a little long/heavy for a 9.5" twist. I'd stick with the 162/168 bullets as my max. Remember, bullet stability is based on bullet length, not the weight. So, the longer a bullet is, the more twist needed to stabilize it.
On your build, if you run a 1:8" twist with a 180 Hybrid at 2650 fps, you have a 1.8 stability factor. That's plenty for that bullet. The issue is getting this to feed in a short action, and getting enough speed for it to work well in a 16" barrel. I know shooters running a 180 grain in a 7-08, but they run long barrels (26"-31") to get the speeds up and seat the bullet out long. A 16" barrel pushing a 180 grain will be moving very slow. A 162 or 168 would be better off to get some speeds up. But it depends on what the goal of the rifle is. Knowing this, it will help.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503641
10/20/16 12:25 PM
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Burton Ranch
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Thank you for all the good info. I would like something compact enough it could double as an everyday pickup gun, but also have hunting applications in west Texas (out to 400 yards). I also enjoy long range plinking, so with any gun I have built if it can hit steal at 1000 that would be a bonus.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503670
10/20/16 12:47 PM
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J.G.
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Mine will be a 1:9", which is a pretty standard twist. I'll work up loads with 154 gr, and 162 gr, then run them down the range. Which ever I like best will be what I stick with.
400 yards, and in will be no problem on coyotes, and hogs. Depending on energy delivery, it will probably be suitable for whitetail.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503712
10/20/16 01:08 PM
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ChadTRG42
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The big debate on the 7mm bullets has always been- do you go lighter (162/168 grain) to get the higher speed for flatter shooting, but lower BC. Or do you run the higher BC (180 grain) at a much slower speed for more drop. There is a middle point somewhere around after 600-800 yards where the 180 grain will out perform the lighter bullets. If the rifle is planned to be used 90% of the time inside of 600-800 yards, then the answer is generally go with the lighter bullet to get your speeds up for the flatter shooting and good bullet expansion. Same principal for the 308 Win. I'll run a 155 or a 168 in my AR-10 to get the speeds up.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: ChadTRG42]
#6503797
10/20/16 02:07 PM
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J.G.
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There comes a point of diminishing returns in any cartridge. Loading super high BC generally means a heavier bullet. And when the barrel is too short to get the high BC up to speed, it's not necessarily a better load. Same is true if your brass can't hold enough powder to get the bullet up to speed.
That was proven with my 7 Rem Mag. I've got a load pushing 180's 3030 fps MV. Chad experimented with the new Berger 195's in the same rifle. Significantly more BC, but the brass couldn't get it up to speed to out perform the 180's. I ran some numbers, and to equal the delivered energy of the 180's @ 3030, the 195's had to leave at 2800 fps MV. Pressure signs began before that velocity was achieved. Thus the 7-300 that is coming soon. More case capacity to push that 195 fast enough. The same holds true for short action chamberings. You won't do yourself any favors by loading a 230 gr in a .308 Win, at least not if you want performance at some distance.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503806
10/20/16 02:12 PM
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ZK-315
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Listening in on this one. Seems like a lot of good info I could potentially use in the next couple of years.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: J.G.]
#6503816
10/20/16 02:16 PM
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Mine will be a 1:9", which is a pretty standard twist. I'll work up loads with 154 gr, and 162 gr, then run them down the range. Which ever I like best will be what I stick with.
400 yards, and in will be no problem on coyotes, and hogs. Depending on energy delivery, it will probably be suitable for whitetail. Would a suppressor on a 16" barrel increase velocity? Also, how much energy is recommended to hunt whitetail?
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Gone to Texas]
#6503824
10/20/16 02:22 PM
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J.G.
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Allegedly it does, though I've never chronographed the same load with and without suppressor. Suppressor length, and type and number of baffles, is certainly a factor.
Round here the ft/lbs I've seen mentioned for whitetail is 1000 or more.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: J.G.]
#6503833
10/20/16 02:27 PM
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Gone to Texas
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6503852
10/20/16 02:44 PM
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Korean Redneck
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Is there such a thing as a twist that is too fast? That's a good question I never thought of. The few times I've had an exact choice of twist, I just got the fastest I could assuming it could never be fast enough.
I'm a dude who likes long barrels!
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Korean Redneck]
#6504015
10/20/16 04:35 PM
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J.G.
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There is such a thing. You can lose velocity, or in extreme cases, over spin a light bullet. Take my 1:8" twist .22-250 that I shoot 75 gr bullets out of. If I loaded 40's and filled the case to book max, the bullet could disentegrate before 100 yards.
One example.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504068
10/20/16 05:20 PM
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Burton Ranch
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Thanks for your insight. Any other thoughts / recommendations for this build based on the intended use and parameters (short barrel / mid-range capability / variety of bullets offered / etc.). I really like the 7mm-08 cal., but since yall seem to have the ballistic and practical knowledge is there a different caliber that could do these things better?
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504092
10/20/16 05:42 PM
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Joined: Dec 2008
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J.G.
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Not necessarily better. If there was a better, I'd build it. But there are other options that will do just as well, just with a different head stamp label.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504129
10/20/16 06:10 PM
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TexFlip
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I have a 16.25" 6.5 CM that is very effective on game out to 400 yards. Getting 2715 fps with 120 grain A-max. My next bolt action build will be a 16.25" 7mm08.
Just to make sure that it is done thoroughly, I go both ways.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504610
10/20/16 11:32 PM
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ccoker
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Cant wait to get my shorty 708 together. Need to check the twist, i dont plan on shooting heavies though, setting it up as a300 and in rifle.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504651
10/21/16 12:10 AM
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kmon11
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Standard twist from Remington when the 7mm-08 was a new round 1:9.25 which my 788 had will stabilize up to the 168gr bullets from its 18.5 inch barrel. I shoot mostly 140gr bullets from it and have for 34 years, figure why change what has been a great combo for 34 years
lf the saying "Liar, Liar your pants on fire" were true Mainstream news might be fun to watch
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504700
10/21/16 12:44 AM
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spg
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This might be irrelevant to your build but I'm getting a 284 built on a finished 28'' 5R bartlein 1/9 and will be shooting 180's. My Smith just set the National Open F class Record with his rifle so I guess he knows what he talking about, I questioned him on the twist rate at the beginning of the build but he assured me it will be a laser beam. We'll see when he gets done with it.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504708
10/21/16 12:51 AM
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Burton Ranch
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Thanks for all the info guys. Sounds like there is a market for short barreled 7mm-08's, now we just need to find a co. that will give us a group discount.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504772
10/21/16 01:27 AM
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Joined: Dec 2008
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J.G.
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My rental rifle is a 20" 7mm-08. The more I shoot it, the more I really like that round. 100-800 every week, is lots of fun. And it's killed everything I've aimed it at.
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Re: Best twist rate for 7mm-08 with a short barrel?
[Re: Burton Ranch]
#6504810
10/21/16 01:54 AM
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dee
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The new eld from Hornady in 162 is salty. At 400yds running 2670fps a 6-11mph wind has no affect on drift. All the 6.5 guys had a .1 or two variation unless running fast and hard.
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