Thread: Recreating a Hornady 139g SST for 7mm RM

I'm trying to simply copy the 139g factory rounds I use...139g Hornady SST for 7RM.

I just pulled a projectile and measured the charge: 77.5 grains of powder in the factory round.

I've checked and rechecked and I measure 77.5 every time. But on every chart I've seen 77.5 is way into the redline. It looks like you get a compressed load by the time you get to 75 grains.

So does anybody know what powder is this? And how much 2217 or 2213sc do I need to get the same whoomph?

Hoping somebody can point me in the right direction.

Why only use a 139/140gr bullet in a 7RM?

Look at stepping up to a 162gr/168gr bullet and get the performance out of the 7RM that its capable of.

From some of the experiences i had with the 139gr SST in a 7mm-08 i wouldnt be using that bullet in a case that can push them much much faster.

Originally Posted by GWH

Why only use a 139/140gr bullet in a 7RM?

Look at stepping up to a 162gr/168gr bullet and get the performance out of the 7RM that its capable of.

From some of the experiences i had with the 139gr SST in a 7mm-08 i wouldnt be using that bullet in a case that can push them much much faster.

Interesting. What happened?

Originally Posted by YosemiteSam

Interesting. What happened?

Bullet blew up on front shoulder of a Sika yearling leaving a shallow dinner plate sized flesh wound. Luckily the copper jacket carried on thru and did kill the animal, but it was a bloody mess.

That was only pushed at 2850 fps from a 7mm08.

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This is the surface explosion on entry

Another example of why I don't run ssts!

You are not able to re-create the load you want by simply dissembling the Round , for two reasons .
Firstly you cannot get the powder because it is not a commercially sold powder and secondly the powder load is regulated by pressure not a given velocity even though the two follow each other to some degree .

Originally Posted by GWH

This is the surface explosion on entry

Attachment 110988

Train wreck

Had the same sort of result at close range with 708 sst but ok at 200m

Mate lost a red hind in November with that 139sst out of his 7m08. close range shot ??50_70mtr. Dropped and got up and ran when he was about to get the knife out.
At 100-200mtr it does a good job on smaller eating reds I have seen him shoot.
Z

Originally Posted by YosemiteSam

I'm trying to simply copy the 139g factory rounds I use...139g Hornady SST for 7RM.

I just pulled a projectile and measured the charge: 77.5 grains of powder in the factory round.

I've checked and rechecked and I measure 77.5 every time. But on every chart I've seen 77.5 is way into the redline. It looks like you get a compressed load by the time you get to 75 grains.

So does anybody know what powder is this? And how much 2217 or 2213sc do I need to get the same whoomph?

Hoping somebody can point me in the right direction.

You might find the the Factory secret powder is more dense than those to powders giving it a greater weight for it's size. I also agree however, You might as well be useing a 708 if you are going to run such a light projectile. I have used the sst in 154 if I remember correctly out of my RM. With very good results, Have now moved on to 162 AMAX,

I'm shooting feral goats out to 500 sometimes. But usually in the 250 - 300 range. I figured the 139 would be AOK for that. I'd get a bigger round for a bigger animal.