7mm twist rate?
- Thread starter DDoug
- Start date
I was thinking the 9 would be better just wasn’t sure. Probably not shoot anything heavier. Thinking the 175s would be about right.
I use a 1-8" twist in my 7mm-08. It'll stabilize everything out there right now, even if I don't push 'em out fast.
It might be a little faster than needed, but with todays tighter tolerances, the tight twist doesn't matter as much as it used to. 162's stabilize just fine out of my 7mm-08 and accuracy is very good with them.
162 from short action 308 bolt face, 180 from mag bolt face
but im really looking at an 8.5-7.5 gain twist for either
assuming you're at 5k elevation yeah you'd probably be fine. but the 9 twist is slow for a 7mm. why limit yourself to high elevations or certain bullets when an 8 twist would get it done everywhere and better
I run 1-9.5 24” and 1-9 22” in 7RM and 7mm08 never had a problem stabilizing any bullet up to the 168. Never tried heavier than that. With that said I’m waiting on a 1/8 for a new 7mm08 18”. Just to round out the collection and experiment. The only steadfast rule I’ve experience when it comes to twist rates is as the barrel gets shorted the twist should get faster. You can plug in the ELD-x info into Bergers twist rate calculator and see what it says. Hope this helps.
Most of my older 7mm's are 9T.
I have one 8.5T
Newer ones are 8T
My 9T 7 SAUM handles the 162 A-Max fine, 9T 7 WSM handles the the 180 JLK's just fine. Running 9 T's in a couple 7 LRM's shooting Hybrids. 284 wIn 9T runs the 180 Hybrids just fine.
New barrels will be 8.5T or faster for me though
I have one 8.5T
Newer ones are 8T
My 9T 7 SAUM handles the 162 A-Max fine, 9T 7 WSM handles the the 180 JLK's just fine. Running 9 T's in a couple 7 LRM's shooting Hybrids. 284 wIn 9T runs the 180 Hybrids just fine.
New barrels will be 8.5T or faster for me though
This is jut my opinion, but the only time I think you need faster than 1:9 is if you plan to shoot the Berger 195 eol bullets. I shoot Berger 180 vld hunters and 175 eld-x out of my 1:9 twist 280 ackley and they both perform great.
How well do they do past the transonic range on a cold sea level day wth that twist?
Because I've shot 7mmRM/WSM for 40 years with a 9 and 8.7 twist barrel between roughly 1295-8600 foot elevation and never experienced a problem with either 168, 175, & 180 grain bullets. I can push them from 3050-2950fps depending on bullet out of my 7WSM. When I had George at GAP build my 7WSM he suggested 1:8.7 twist and it has suited my hunting needs. If the Op wants to run an 8 twist...run an 8 twist. Shooting a 7SAUM (26" barrel) with a 175gr ELD-X he could possibly push it to 3000fps taking greater advantage of the bullets BC. I've pushed 180gr Berger Hunting VLD's to 3023 fps out of my 26" barrel but I've found it shoots best around the 2950fps range.
From the Op's post (type of bullet) it sounds as though its a hunting application and not an ELR rifle.
All my 7mm bbls are 1-9, whether they're on a 7-08 Improved 30*, straight 284, or 280 AI. So far, haven't shot anything heavier than S168MKs out of the 7-08, but two 284s & the 280AI are shot most often with Berger or JLK 180VLDs, as well as Berger 180 Hybrids. Had not considered a faster twist rate, since the only way I can get more than 2800fps with the 180s is to use RL17. Doubt going with any of the heavier 7mm bullets would net me any worthwhile advantage over the 180s, since I'm not an F-Class shooter.
