Home Forums Hunting & Shooting Ask The Gunwriters 7x61 With 12" Twist

I've a new Schultz & Larsen M60 with a 12" twist that I am testing. Does anyone here have experience with heaver bullets, i.e., over 140 gr. in this caliber? The most common factory load is the Norma with 154 gr. slugs, but I wonder if that weight will stabilize. I'm looking for advice to get me off on the right foot.

Bandu: Back then the 7mm Weatherby had a 12 twist,too...as did the 270 Weatherby IIRC. The S&H was a contemporary.They were all about the Weatherby concept of light bullets and high velocity then,and lots of Hornady's were used.

All my 7mm's have been 10 twists or faster,so can't speak to a 7mm tube that slow, but stuff of 160+ gr may not stabilize;especially some of our modern and very long bullets. I would stick with 154's and under. Phil Sharpe was no dummy and if they loaded 154's they should work.

Hope this helps.

I have a 7mm Wtby. with a 12 inch twist.

The 140 grain bullets work just fine, but I trued some boat tail hollow point match bullets in 168 Sierra, and I think, 162 Hornady.

The 12 inch twist would not stabilize either one, but I had loaded them down to about 2700 FPS. 3000 FPS, or as fast as you can get them to go might stabilize them. The only way to know for sure is to try them.

Years ago I played with a 7mm Wtby for a while it had the 12 twist barrel and it would stabilize a 160 Sierra. Never tried anything heavier though. Mostly used 139gr. Hornady. These days most of my 7's have 9" twist barrels.

Thanks to all of you for the great information. I have some Norma 154s to evaluate and I'll try them first, before I start reloading operations. From your various comments, it appears that the velocity and perhaps the form of the projectile determines the stability at this slow twist. If the rifle will handle 140s, then I'll be happy.

B-

Some years ago I had a 7mm Rem Mag with a 1~11" twist. I didn't know what the twist was, so I loaded 160 gr. bullets. And guess what? they shot all over the place. I immeadiately pulled the barrel and measured twist and then I knew why. The rifle and I parted company!

I have always thought that a 7mm Mag was at it's best with 150-160 gr. bullets. I have other rifles to shoot the 140s in. But then I tend to favor med to heavy bullets for caliber. (Whether it's right or wrong - it's the way I am, and I make no apologys for that!)

Were I in your shoes, I think I'd try various bullets and see what I can find. Specifically; I'd try the 154 gr. Hornady round nose. Or any other blunt-nosed bullet. Likely the shorther bullets will work better. If you like the rifle, I'd not off it until I had exhausted all possibilities... YMMV

GH

Interesting. I have so much to learn. Good luck with your efforts.

I bought a 7x61 S&H on a commercial FN 98 action from an older guy.

I got it for $250 so I mostly reached for my wallet. The handloads anddata he passed along was all for 140 grain bullets.

I planned on using it with 154 Hornady's.

I guess I will have to shoot some and see.

I have owned two S&L M60s and one M65, all in 7x61 with 12" twist. Having other rifles to play with, I had never given any of them a thorough evaluation. I appreciate all your comments and suggestions; it should make load selection much easier for me.

It seems my best bet is to concentrate on the 140 gr. and lighter bullets. If I want to shoot heavier bullets, then go with RN or Short Spitzer bullets at maximum velocity. I will try to post my results as I conduct my trials.

The factory 7x61 ammunition available at the time from Norma used 150 grain and 154 grain bullets. You should be fine.

Ballistic Reference:
https://www.24hourcampfire.com/ubbth...s/5762606/Re_Tell_me_about_the_Schultz_a

A 1-12 twist in ANY 7mm round is going to have a hard time stabilizing lead-cored spitzers over about 155 grains, and ANY of today's monolithic or heavy-jacketed spitzers much above 140 grains.

I once had a 7x57 with about a 1-12 twist (not my choice, believe me) and it wouldn't shoot any bullet longer than a 140 Nosler Partition under 2" at 100 yards. The heaviest spitzer it would shoot well was the 154 Hornady Spire Point.

And contrary to popular belief, more velocity doesn't help very much.

I have one with a 1-14 twist, it shot the Norma 154 gr loads well enough. I am thinking about rebarreling it, and chambering it for 7mm RM. Anybody ever do that? It has some class, my main reason is that Norma dose not load ammo anymore and cases are getting hard to find.

Interesting... I did a quick calculation of velocity vs. twist rate and, somewhat to my surprise, confirmed your observation. For example, the 154 Hornady Spitzer moving at 2600 fps through a 12" twist barrel leaves the muzzle at a rate if 2600 rps (rotations per second). The same RPS will require 3000 fps or so through a 14" twist.

On the other hand, that same bullet would be stabilized down to 1700 fps through a 8" twist barrel.

Extrapolating further, a 175 gr 7mm bullet is stable when fired at 2400 fps through a 8" twist, where the RPS is 3600. That same RPS requires 3000 fps through a 10" twist and 3600 fps through a 12" twist.

Interesting thread! For several years, I loaded for, and did some hunting with, a .300 Ack. Imp. that sported a 14" twist in a 24" barrel. With good using loads, I could get 3150fps with 180's and a bit over 3200 with 165's. On paper, out to 200 yards, this rifle shot well with the 180 Sierra FB, 180 Hornady SP, and even the 200 grain Speer spitzer. It also shot the 165 Nosler PT and Hornady SP very well. The 180 Sierra boattail wouldn't stabilize and, as expected, wouldn't group.

When first used for hunting, the 180 Sierra FB load was used; however, after an elk or two was taken, it was apparent this bullet began to tumble upon impact. Even though it shot well on paper, it was not stable enough to mushroom and penetrate the way it should. We ended up using the shorter 180 Hornady SP and tough 165 Nosler PT for hunting loads, and these two bullets always seemed to expand and penetrate in the way expected.

M Bell

I located an old ad for the Schultz and Larsen M60 from 1959. Hard to read but it says that the original Norma 7x61 S&H load uses 60.5 grains of Norma Special #104 powder to push a 160 grain PSPBT bullet at 3100 fps. These published velocity claims were later found to be overly optimistic. This led to the later release of the 7x61 Super load mentioned above that uses 150gr/154 gr bullets and an updated interior case profile to increase powder capacity. Based on this, it seems that Bandukwallah can load up to 160 grain bullets for his M60 rifle and the 1:12 twist will stabilize them adequately.

Thanks, all of you for the great input. Applying the Greenhill Formula (T=C(D^2/L):

Speer 145 gr. SpFB has L=1.1", and T=13.2", RPS = 3200 (Yes)

Sierra 160 gr SpBT has L= 1.23" and T=11.8", RPS = 3000 (Maybe)

The Speer 160 gr SpFB has L=1.22", and T=11.9", RPS = 3000 (Maybe)

The 168 gr Matchking has a L=1.33", and T=10.9", RPS = 3000 (No!)

The 175 gr SpBT has L=1.44 and T=10", RPS = 2900 (No!)

The 175 gr Speer SSFB has L=1.22 and T=11.9", RPS = 2900 (Maybe)

So, considering everything, staying below 160 grs and sticking with FB bullets should be my ticket to success. However, and this is unexpected, a 175 gr. RNFB bullet might be worth looking at.

N.B., the "L" values were scaled from photos