Thread: 7mm08 loads and a short barrel

Originally Posted by grandpamac

Greetings,
Early on a lot of people went to AR2208 and IMR4064 in the 7mm-08 due to the difficulty of getting top loads of 48 to 50 grains of AR2209 in the case. The Hodgdon data for the 139 grain Hornady Interlock is some of the old data. From my notes 42.5 grains of AR2208 (a grain under max) gave 2,710 fps from a 19 inch barrel. 43.5 grains should produce 2,750 fps or a little more. Data for AR2209 is more of a problem due to the change in speed around 2002. The current stuff in the plastic containers will likely take around 1.5 grains less of powder for the same speed based on my test firing in my 6.5. Adding a bit back for the Hodgdons load being below book pressure leads me to a book max load of around 49 grains of new AR2209 for around 2,800 fps in your 19 inch barrel. You will have the data to compare with this. This data is for the 139 grain Hornady interlock only.
Regards Grandpamac.

Some reloaders mistakenly think that compressing powder is somehow a bad thing. I have loaded 51.5 grains with a 140 ballistic tip boat tail, and it compresses fine and stays where it should be. You can load a touch more with a 139 grain interlock.

So far 2209 gives faster velocities than 2208/Varget, I dont know why no one else is using 2209 in this cartridge.

I have both old and new 2209. Wtih other cartridges I load with the older powder (.30/06, 9.3 Mauser, 7x57, .243 etc) I am getting consistantly 100-150 fps less in any load than I did with the new powder, and the Hodgdon and ADI data corresponds with the faster powder. I have to bump all my loads up by 1-2 grains to match the modern 2209 powder, so I think that it is quite the opposite.

This rifle is a specific example of this - in this 7mm08 with a 19 inch barrel, with 50 grains of new 2209 and a 139 grain interlock, I am getting 2730 fps. (Book max is 50 grains with a 24 inch barrel for 2900fps, so taking short barrel into account, this is about right.) To match that result with the older powder I have to load 51 grains. So it is consistant with my other loads for other rifles with this powder and the current ADI/Hodgdon data.

(I have a perfect correspondance with the "new" powder matching the ADI data with the results I get in the 9.3x62 I remember in particular. To the point that I use that knowledge - to make cartridges just for sighting in scopes etc I load the same max load from the book, which the velocity I get matches very closely with the data, but swap to the old powder so it make it a bit lighter load which is easiaer on my shoulder because its 200 fps slower...)