Gordon's Reloading Tool and SAF

[sgt_zim]

the default data set in GRT for SAF shows an initial pressure of about 10800. This is incorrect. IP for SAF in all calibers should be 3626 PSI.

fortunately, this was an error in our favor. While doing LD this weekend for my 280 AI, I ended up with MV about 200-250 fps slower than predicted for 160 gr SAF. Still got some excellent groups, best was about 0.4 MOA at 2650 fps. Good, but I need that bullet at around 2800-2850 to do what I want it to do.

as always, start low and work your way up.

 

[Nevada Mike]

How do you like the 280 AI? I am having one built by Aaron Little on a Model 70 with Kreiger barrel. It will probably replace my old 7mm RM for a lot of my hunting. I am focused on 140 - 150 grain bullets, mainly.

 

[sgt_zim]

So far so good.

My best friend and I are doing LD on the same guns, to be used for mountain hunting.

He's also taking the light bullet route. I've pretty much always been a fan of heavy for caliber.

 

[Nevada Mike]

I use 160s in my 7mm RM. Noslers and Swift AFs, mainly. Very accurate (sub MOA). But the rifle is about 9 lbs... and I am getting older. Aaron is building a lightweight for me in LH Model 70 Classic and I am upgrading it from 7X57 to 280 AI. For the hunting I do it will serve me better.

 

[sgt_zim]

what powder are you planning on using?

Ramshot Magnum has worked well so far and seems to have a more elongated pressure curve. I got to a little over 2900 fps with the Oryx, which was really my cutoff point anyway. BC on those is so low, even at 2900, it only keeps me above 1500 ft-lbs out to about 400 yards.

 

[Nevada Mike]

what powder are you planning on using?

Ramshot Magnum has worked well so far and seems to have a more elongated pressure curve. I got to a little over 2900 fps with the Oryx, which was really my cutoff point anyway. BC on those is so low, even at 2900, it only keeps me above 1500 ft-lbs out to about 400 yards.

I my 7mm RM I use RL22 or H870 both perform well, but the RL22 is better for 140 grain loads, and H870 for 160 to 175 grain loads.

For the 280AI I have IMR7828 and 7828 SSC, Norma MRP, and the RL22 and H870 mentioned above. I am far from starting load research and development for the 280, since I do not have the rifle in hand yet and I am busy prepping my 404 and 375 for an Africa trip in a few months.

 

[Scrumbag]

@sgt_zim This is a not unknow problem with some of the harder bullets in GRT.

Nosler Accubond in larger bores has a higher IP was well. I've had a chat with some of the admins at GRT and basically the higher IPs for Nosler bullets after discussions with Nosler. The admins note the IPs for the Noslers are high and they were supposed to be revised but unfortunately Gordon passed away a few months ago and it hasn't been done yet. I'm guessing Swift A-Frames might need a higher IP but not that high.

(By the way 280AI looks an excellent cartridge, I have a 26" barrelled 7x64 and I like it a lot. a 160gr Sierra SBT is my bullet of choice).

Scrummy

 

[sgt_zim]

I got on the discord with them, and they suggested standard IP of 3600+. When I changed that value in the calculation, the labradar readings I was getting lined up very closely with what GRT was predicting.

Speaking of Nosler, they seem most willing to run pressure right up to the very edge. If you look at their data on 280AI and 7mm RM, they completely overlap, bottom to top, at least on the heavier bullets.

 

[Scrumbag]

Well, I can kinda see why. Case capacity isn't that different.... Though I must admit, I find Nosler reloading data a bit hokey... (Love the bullets, data rubbish in my view).

 

[shark_za]

Do you have some details on your 280AI ?
I know you are lefty and our tastes seem to run in a similar direction , would like to see what you did there as I am also looking to build a dedicated Gemsbok rifle.
I have my mind set on a .300 H&H but a good 7mm will also work.

 

[sgt_zim]

It's an off-the-shelf Savage Timberline, 22" fluted barrel, 9.5 twist, 4 rd detachable box magazine. Topped it with a VX-III 2.5-10x40. Recoil is mild with 160 gr A Frames and 156 gr Oryx. We'll see what it feels like next weekend when I put some 175s through it.

I probably should have gone with IMR 4831 for the 2 lighter bullets, but even with Ramshot Magnum, I got several good groups. I think the Magnum will work out even better for the 175s, and honestly, all I'm looking for out of the 175s is MOA at 2750 fps. That puts it in the same class as 7mm RM.

High Country model is a little lighter, would have gotten it but they don't make it in LH.

Intent with this is for high country elk and mule deer.

 

[Nevada Mike]

I have a custom LH Model 70 Classic with 23" Krieger barrel (1:9) that Aaron Little is working on. It was a 9lb. 7X57, which seemed ridiculous to me so I sent it to Aaron to restock and rework to about 7-1/2 lbs. or so. On a whim I asked him to use the same barrel, but chamber it in 280 improved. This will not be a 'classic' caliber but much more useful to me.

 

[Nevada Mike]

Photo of my soon-to-be 280AI and the blank that will be used for the stock...

 

[Scrumbag]

@Nevada Mike looks lovely!

 

[Nevada Mike]

Thanks, Mike. One of those "hurry up and wait" deals. Aaron says he can start in September. He is going to turn down the 23" 1:9 Krieger barrel, skeletonize the mag box, make a new, lighter weight stock, then blue everything again. I'd like to finish at about 8 lbs. with the Swaro V3 included.

Getting harder to lug my 9 lb. 7mm RM around these hills!

 

[Scrumbag]

Thanks, Mike. One of those "hurry up and wait" deals. Aaron says he can start in September. He is going to turn down the 23" 1:9 Krieger barrel, skeletonize the mag box, make a new, lighter weight stock, then blue everything again. I'd like to finish at about 8 lbs. with the Swaro V3 included.

Getting harder to lug my 9 lb. 7mm RM around these hills!

Sounds good!

 

[Bob Nelson 35Whelen]

Photo of my soon-to-be 280AI and the blank that will be used for the stock...

View attachment 470156

View attachment 470157

@Nevada Mike
Manage don't out that rough sawn fence paling on it. Save the hassle and send it to me then get a nice piece of wood.
Ha ha ha ha
Actually it should come up nice with a hand rubbed London oil finish
Bob

 

[Bob Nelson 35Whelen]

Well, I can kinda see why. Case capacity isn't that different.... Though I must admit, I find Nosler reloading data a bit hokey... (Love the bullets, data rubbish in my view).

@Scrumbag
Mike I use a fair bit of reloading data from nosler and find it good. Never given me any pressure problems in any cartridge I've loaded using their info and velocities are pretty accurate to go with it.
Hornady No 10 on the other hand is the most conservative loads I have found.
Bob