7mm Magnum and 139 SST Interlocks

TackDriver284

Handloader
Feb 13, 2016
1,864
595
Going to try to work up a some loads for deer season because I only have a few loaded 160 Accubonds from last year. I like to salvage bullets I already have on the bench, looking to use the 139 grain SST Interlock ( old red box ) and RL-19 and see what pops up at the range. Looking to push it close to 3300 fps with the 26 inch Brux barrel.

Any great powders that you guys use with 139 grain Hornady SST Interlocks in the 7 Magnum?
Thanks
 

1Shot

Handloader
Dec 5, 2008
1,435
5
The Hornady 139 Interlock was the first bullet I tried when I went through my 7mm Mag phase. I was using AA3100 back then but that was before all these newer slow burners that have come along. This powder was really accurate with all bullets I used. I did not like the results of the 139 Interlock. At 7 mag speeds it really blew up and would not exit and deer would run off a good ways leaving not much to no blood trail and was hard to find in the east NC jungle I hunted around. Best deer bullet I found was the 154 Hornady Interlock or SST for the 7 mag, it would exit and give you a good blood trail. I have made longer shots but the first deer I killed with my 7mm Rem mag was what I think was the best shot I ever put on a deer and I have killed hundreds of white tail doing crop damage control and hunting them for 50 years. Rifle was a Rem 700 Stainless. Shot was on a buck standing broadside at exactly 300 of my paces and I pace a yard or just a little longer with my long legs, I am 6' 2". I was hunting in a powerline cut where we had shooting houses placed but I kept seeing a nice buck around 700 yards away from my shooting house so I decided to take a ladder stand and get about 100 yards away from where I kept seeing him. The only place I could put a stand and see good was on a tree that was only about 3 inches around and I could only use two sections of the stand making it 10 ft off the ground and I had to stand up all the time. I placed the stand so I could brace off the tree to steady my shot. Wouldn't you know it. Deer came out in the opposite direction behind me at about 100 yards. When I tried to easy around to get a shot the stand made a SQUEEK and the deer took off running. He ran down and across to the other side of the powder line cut and stopped broadside to look back just before he went into the woods. Only shot I had was off hand. I had been shooting off hand pretty good with my M1 Garand in over the course high power matches so I got into my best sling and body brace position. I had the rifle zeroed 3" high at 100 so I was dead on at 300 yards and I knew from previously pacing between power line frames I was close to 300 yards away from the buck. I started my circle movement watching the cross hairs circle on the bucks shoulder and started my squeeze on the trigger. BOOM and a second latter POP when the bullet hit. When rifle came down out of recoil deer was gone. That deer ran about 100 yards into the pine tree and green briar jungle leaving NO BLOOD TRAIL. Only way I could tell where it went was from the pine straw that was disturbed and I did a half circle grid search and finally found it. Shot was a perfect heart shot with no exit. Long story short, after shooting between 40 and 50 deer with the 7 mag with a number of different bullets I got tired of having to trail deer a good ways in the jungle to find them. Traded 7 mag for a 25-06 and never looked back. When you shoot a deer with the 25-06 99% of the time the only trailing you do is watching it drop on the ground in it's tracks. Can't understand how or why deer ran off so far when they sloshed on the inside when you found them but they did. My buddie has the same experience with the 7 Mag. They don't run off on my 264 mag so why the 7 mag? Head scratcher for sure. Hope you have better experience.
 

TackDriver284

Handloader
Feb 13, 2016
1,864
595
Gunner46":1924xsun said:
Are you trying to make venison burger in the field ?

If you see the Nosler manual, max speed for a 24 inch barrel is over 3,300 fps. So with a 26 inch barrel which I have, I should approach speed close to that or more and the magnum calibers does shoot better close to maximum loads due to my experience.

I normally shoot through the lungs so I wont have to worry about bloodshot meat.
 

TackDriver284

Handloader
Feb 13, 2016
1,864
595
1Shot, I have had a few deer run off with double lung shots, its where I prefer to shoot them at, and find them 10 to 40 yards mostly. Most of the deer have dropped on the spot or took a few steps and keeled over. I have used mostly Ballistic Tips and Accubonds. The Accubonds tend to frag less than the Ballistic Tips in my experience. Both are great bullets
The SST is something I have never tried and has been sitting on my shelf for about 20 years, its time to use it. (y)

Would reducing the speed, like 3000 fps, help the SST stay together without fragmenting so the bullet can exit?
 

Bruce Mc

Handloader
Oct 26, 2005
1,051
107
Mark, the antelope photo in my signature was killed with a 139 Interbond and a load of 69.5 grs of Reloder 22. It chrono'd at 3300 fps. 26" barrel model 70.
 

1Shot

Handloader
Dec 5, 2008
1,435
5
Slowing the 139 SST down would make it hold together better so it could exit. I know a fellow that slowed his 7 mag down to about 2900 fps with 145 gr Speer hot core bullets and he swore it worked much better for DRT results than speeding it up to full throttle. I use the 130 AccuBond in my 264 Win mag at 3350 fps (27 3/4" barrel) and I have killed 30 to 40 deer with it and not a single one has gone more than a jump or two with most like the ground has been jerked from under them. Yep Ballistic tips work great if kept under 3000 fps impact in most calibers. The 125 gr BT in 30 cal. is my favorite deer bullet.
 

Polaris

Handloader
Dec 16, 2009
1,223
0
I've run the 154 SST from a .280 Rem and was not happy at all with the terminal effects on large deer. Fragments in the meat well off of the impact vector, bloodshot, etc. I had a mature buck eat 3 of them in the chest at close range before a 4th parted his antlers. He was dead on his feet, but none of the 3 exited and blood trail would have been very scant. He covered nearly 100 yards, 2 of the bullets should have quartered into off side shoulder and anchored him in his tracks, and would have with the speer GS I currently shoot, but turned into shrapnel instead. Ditto with the .30 150gr in my wife's .308win, fragmenting and failing to pass through with only a rib cage impact. I suspect the effects would be amplified with the 139 at your predicted speeds, even around 3000, as mine were moving slower in the .280. I would work up a load still, and purchase some more stout 140+/- bullets. Use the SSTs for some good field position practice.

I have taken one game animal, a coyote, with the 139 at extended range and the results were more promising.

That being said, both bullets worked up extremely accurate loads in my rifle, and I still use the 139 for casual shooting and a couple of "hunter" matches my local club holds in the fall. I also still pack it as a "power line load" due to it's flat shooting nature and fine accuracy, but have yet to put one into a deer at range. I would not recommend this bullet on large deer though.
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
I use RL26 in my 7 WSM with 140 Partitions and BBCs for 3300.. pretty laser beam like.
 

cloverleaf

Handloader
Sep 10, 2006
3,982
377
1Shot":1ic7bpi7 said:
Slowing the 139 SST down would make it hold together better so it could exit. I know a fellow that slowed his 7 mag down to about 2900 fps with 145 gr Speer hot core bullets and he swore it worked much better for DRT results than speeding it up to full throttle. I use the 130 AccuBond in my 264 Win mag at 3350 fps (27 3/4" barrel) and I have killed 30 to 40 deer with it and not a single one has gone more than a jump or two with most like the ground has been jerked from under them. Yep Ballistic tips work great if kept under 3000 fps impact in most calibers. The 125 gr BT in 30 cal. is my favorite deer bullet.

Dads only load (that I can find...) was a Speer 130 gr boat tail and eventually Hot Core. Nothing ever got away and most things were DRT. He used 65 Gr of 4350, whatever that meant for velocity. It was DEADLY, deer, antelope, Jack rabbit, porcupine :) medicine. He dad so much confidence in the Combo that its what he took for his only Elk hunt. Wish he would have seen an Elk. CL
 

TackDriver284

Handloader
Feb 13, 2016
1,864
595
First and quick trip to the range, done round robin on six 3 round charges in .3 increments. Looks like a good deer load with the SST Interlock with 65.5 grains of RL-19 at a speed of 3,100 fps average with 8 fps ES. This speed should do it without too much frangibility hopefully. I have not pushed it further nor will waste my time fiddling with it. Group is reasonable for 300 yards and under.


Side note, maximum charge in the Nosler manual states 65.5 grains at over 3,300 fps, and according to Quickloads after inputting my data, I found that my H20 case capacity is 5.25 grains more than the standard, it could be reason why its pushing it slow. It seems I have more room to push it faster. Just a thought.

9nahl1sl.jpg
 

SJB358

Ballistician
Dec 24, 2006
31,398
757
I think you’ve got a winner.

Funny but my fireform load is 65 grains of IMR4350 and a 139 Hornady Interlock. Usually runs about 3150-3200 depending on brass for my Mashburn. 140 Accubonds shoot the same and I have no trouble knocking steel down at 400 with them.
 
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