Say a guy has access to a Remington 700 SPS Varmint with its extra long 26" barrel that features a 12 twist. The guy wants the barrel chopped to 20 inches to make the rifle more handy. Problem is the twist. Will the 12 twist stabilize 175 MK if cut off to 20 inches. Without the extra 6 inches of barrel, the velocity will be reduced by 175-300 fps (depending on how much velocity is lost per inch of barrel with a given load). Without the velocity, will the 175 MK stabilize in the 12 twist?
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Simple question: barrel length/twit/velocity/stabilization
- Thread starter dukelog
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I have done some research and from what I found out the 12 twist rate wont affect anything under the 190+ gr loads. Had a similar situation and I decided to cut and thread at 22" and have had no problems 168gr. I have not shot 175gr out of it since I cut it down. So I dont have an actual accounting for the 175gr but my research brought me to believe it would be fine. Hope I helped a little anyhow
Not exactly your twist rate but I did cut my 24" 5R w/ 11.25 twist down to 20" to make it more handy as having a can hanging off the end of 24" barrel was just plain long. MUCH better I can tell you yes...168's and 175's out to 800 = 
A) 1:12 twist is marginal with the 175, 1:11.25 is optimal with the 175 and most people can get away with up to 180-190s with a 1:12.
B) my guess is that you will lose more like 75-110 fps from chopping 6" off the barrel.
B) my guess is that you will lose more like 75-110 fps from chopping 6" off the barrel.
Yes it will stabilize the 175 fine if you whack it off. I've done it plenty and not just read about it on the
Internet.
Internet.
I have a sps varmint with a 12 twist and I cut it to 18in. velocity was cut 300fps from a26 in barrel. I didn't really try the heavier bullets but with 155 sierras I was able to ring steel reliably on a 36 in plate at 1k. MV was about 2625. I didn't really intend it to go that far as my intentions were to have a handy lightweight hunting rifle. I know you were asking about 175s but thought you might be interested in other options.
Buy Bryan Litz's new book on his website or Amazon Smile, which supports the Wounded Warior Project. Great in depth discussion of modern bullet design and shorter twist rates to launch the heavier long bullets. Also discusses how inaccurate chronographs are except the MagnetoSpeed V2. V3 series has apparently been having programming issues! Very interesting read.
I have a pair of AI .260s, one in 24" and the other in 26". My Magnetospeed V3 shows about 60fps loss going to the 2" shorter barrel. Bit different animal than your .308, and not 6" either. There's a thread/article where they lop and inch off at a time and crony it.
I'm not trying to hijack this thread. I actually intend to do a little more research and start a new thread.
A quick google search for this book... which I'm not sure which new book you're describing. He seems to have 3 published in 2014 led me to this article. Ballistic Program Inaccuracies
I'm probably going to have to get the kindle version of one of the litz books and check it out, but in the mean time after reading this article I'm at sort of a loss as to how anyone ever hits anything. The more I learn the more it seems like having A. an accurate LRF (based on the review here Rangefinder Binoculars Reviews & Field Tests: The Models & Specs | PrecisionRifleBlog.com this means the now discontinued Terrapin which costs $2,000 if you can still find one) and according to what you wrote a $360 Magneto Speed chrony and an accurate weather station to even begin to have certainty of making long range first shot hits with any consistency.
You nailed it. The book I was referring to is Modern Advancements in Long Range Shooting (Volume 1). Found the whole read very enlightening. He has more volumes to follow!
If everyone just bought Bryan Litz's books, then there would be far less discussion on this forum.
Seriously though, buy Litz's book, and you will quickly learn you don't know shit about shooting. We've all been using old data.
