Home Forums Hunting & Shooting Custom Rifles & Wildcats 7mag build barrel length and twist?

I’d like to go with 25 inches for a blend of speed and handling. I need to shoot copper bullets, so they will be longer then lead equivalents. Something like the 168 grain Barnes TTSX. Can I get away with a 1:9 inch? Or do I need 1:8? Which would be better in a slightly shorter, 25 inch barrel? Or is that a bad idea altogether?

I’m sure the 1:9 would be fine, but if it’s a custom install, I’d go the 8 twist just in case. 25 should be a great compromise, but the same could be said for a 23.

You need an 8 twist for that bullet (it's actually a LRX). I built my 7mm mag with a 9 twist but if I had it to do over I'd go 8.

25” works, and 8 twist is the way to fly

Right, the 168 Barnes is the LRX. My bad.

If I had to drop down to 150 gr, would 1:8 be too fast? There are definitely more lead free options in 150 gr. I probably don’t really want to build a rifle around just one bullet choice now that I think about it.

8” will work well with any common bullet choices in 7mm

An 8 twist is the way to go. It will handle 150gr monos just fine.

8 twist, 26 inch barrel

This is a sporter, field carry, build. I do not want a long, heavy bbl. I’ll be carrying the thing more than shooting it.

Generally speaking, if on the fence, are you better off with more twist out of a slightly shorter bbl, or does it matter?

I would avoid building a 7RM with a barrel shorter than 24". I don't want to put up with the increased muzzle blast and the loss of velocity. I also have found that I don't do my best shooting from field positions with a light 7RM. ie, less than 8.5Lbs or so. I carry my rifles in the hope that I'll get to shoot them and a slightly muzzle heavy rifle seems to work best for me. Oh, I might go with an 8 twist.

The barrel length doesn't matter when it comes to twist. More twist is better than too little, any supposed accuracy loss with light bullets and fast twists is theoretical at best. The only time a fast twist might hurt accuracy with light bullets is if the bullet is poorly balanced which isn't the case with most good bullets today. I've got an 8 twist .223 that shoots 40 gr ballistic tips into one ragged hole, it wouldn't do that if fast twists caused accuracy problems. More and more long 7mm bullets are coming out, Barnes has the 168 gr. LRX, Berger now has a 184 gr. and Sierra has a 197 gr. Years ago a 9 twist would handle most any 7mm bullet but today that's not the case. You're not going to hurt anything with an 8 twist instead of a 9 but you will limit your options if you go with the slower twist. It's a no brainer in my opinion.

I agree with you about the 24" barrel. Mine's 24" and I wouldn't go longer for a hunting rifle, it wouldn't even bother me if it were an inch or two shorter. The velocity loss is overblown but longer barrels are significantly more of a pain to carry.

Unsuppressed I would go 8 twist and 24".

My current 7RM has a 23" barrel and I wouldn't want it any shorter. If building I would go 25" as a compromise. A 1 in 9 will be good for everything up to the 195 Berger but some of the Custom makers are producing 200 grain bullets so I would go 1 in 8 just in case I wanted to experiment. If in doubt get a 26" barrel and you can hack it down if it is too long for you.

I shoot a 23” barreled 7 Rem Mag.... and I like it a lot. I chopped it from 26”” to 23”.... and lost only 40-60fps depending on the load. It still shoots 160/162s at 3k+ pretty easily, and handles way better than it did at 26”. It weighs 8lbs on the nose, and recoil is not bad.... it’s spunky, but not bad. I’ve shot the 145 LRX at 3200+ out of the 23” barrel... though I’ve never shot a critter with one.

I’ve got a 7RM that is currently getting rebarelled. I cooked the 21.5” barrel and will be going 24” on the next one. The balance of that rifle is great, but it could use a touch more muzzle bias, hence the additional length on this next barrel. The extra velocity won’t hurt, either. Handling in the woods is nice with shorter barrels, but blast becomes an issue, as it was with this last 21.5” barrel. IMO, 23-26” is about right on a 7Mag, depending on the type of build.

24” 1-8 twist .

What action?

Hint................

I have rifles in 7x57mm Mauser, 280AI, 7mmRM, and 7mmSTW.
I like a 140 gr Nos Bal Tip or 140 gr Nos Accubond.
I would tolerate a 139 gr Hornady SST.

I have killed animals with 162 gr SST and it kills them, but I want a lighter bullet.
I have killed animals with a 120 gr Nos Bal Tip, and it kills them, but I want a heavier bullet.
I have killed animals with 180 gr VLD hunting and it does a terrible job. I have to shoot many holes in them to stop them. Little pencil holes.

If I cut an inch off both ends of the barrel blank, on the rifle will be somewhere between 23" and 29". They all work.

I'm running two 7mm Rem Mags, both with 24 inch tubes. One is a 9 twist that shoots 180 Bergers well. I like both but wouldn't mind having a 25 or 26 inch on the next one. 24 would be my suggested minimum for an all around setup, with 25 maybe slightly better. 9 twist is great.

My 7mm mags have 26 and 27 inch barrels.. Never wanted anything shorter..