Thread: 7mm08 loads and a short barrel

Originally Posted by Steven708

I’m using 42gr of 2208 white river primer and 140gr vld through 16 inch AB3 with stealth suppressor. Good grouping at 100 yd and 2645 fps. Not too much room left in the case but no crunching & rounds sit nicely in the mag.

Yip using the same load through 16 inch howa.Sacks deer

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.

Staball 6.5 might be worth a look. I’m half a grain under book max and 4 inches shorter than the test barrel and roughly around what the books says velocity should be with a 120grain BT. Accuracy is also excellent.

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...)

I use 2209 in a couple of my 7-08 loads aswell. 120gr NBT and 139gr interlock. The 120nbt load is very compressed.

Still alot of misconception out there about powders & how they work, the “best powder for a short barrel” yarn comes up all the time. Im yet to find a scenario where a the powder that generates the best velocity for a given pressure in a long barrel isnt also the same one that gives the best velocity in the short barrel.

If maximum velocity is the goal the way i approach it is try find the slowest burning powder that you can fit enough of in the case, to the point where ideally you reach your maximum safe pressure just as the load is becoming compressed. Faster burning powders generally take up less volume in the case, slower burning magnum powders take up more. If the powder you use is too slow/bulky for your chosen cartridge/projectile combination, you wont get enough in the case to achieve maximum pressure & therefore velocity. If you choose a powder that has too fast of a burn rate, you will reach maximum pressure whilst still having room in the case for more powder, and you may not achieve the desired velocity(inside safe pressure limits) due to the pressure ramping up to peak fast and then falling off fast so the duration of “push” time on the projectile is shorter. If your able to create a combination where you have the slowest burning powder you can fit enough of in, you can end up in the scenario of having a full case, the same peak pressure as the faster powder burn, but a longer duration of “push” and therefore the best velocity achievable with said cartridge


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I've got some 120bts if you need some.
I thought they were a great pill. We only ran them at 2600fps as a youth load but they would easily drop big reds at 300 yards.
162eldm would be my pick if you want a long range projectile

Originally Posted by John Duxbury

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...)

Greetings again,
Looking at my shelves I have a few 130 grain Speer plus 139 grain interlock and SST, 145 grain Speer and 150 grain Remington projectiles. There is also AR2206H, AR2208 and 3 lots of AR2209. In my archives there is load data from 1980 from Bob Hagel and Ken Waters plus others over the years. I feel some test loads are coming.
Neil.

Iv had a play over the past couple days with 150eldx Iv found unless the the lrab is a stiff load it won’t shoot (I’ll revisit when it’s not my only going rifle) easy enough sub moa accuracy with eldx worst was just over an inch best was .610 I’d normally play further but I can hardly see the target behind the awfully thick reticle on the vx3hd and I’m no comp shooter so thought bugger it il load the .6 load and have a crack at my 4” 400yard plate I loaded 4 shot a peacock at 266 hit it but hit it low using hornady app first shot on gong was a clean miss no idea where it went gongs to small and was hanging on a fence into long grass used applied ballistics for the next shot which told me a .5 moa difference and went 2 from 2 im satisfied I can go hunting its also 100fps faster than the lrab and not seeing the signs on the brass like I was

Further developments after the OP:

Typical. The gun shoots better with the most expensive bullet....

162 grain ELD-M with 41.5g of 2208 at 2633 fps.

upload pictures online

Don’t try bergers then

You def need to try bergers

Greetings,
Perhaps the search is over? I was reading some load tests from 1980 by Bob Hagel in Handloader. He tested loads both in the Remington 700 varmint special with a 24 inch barrel and a Model 788 with a 18.5 inch barrel. His velocity loss with IMR4350 was 150 fps plus or minus a few fps for most of the projectiles he tested including the139 grain Hornady. The early 140 grain factory load was loaded with the 139 grain Hornady and a non canister grade of WW760. It lost 150 fps too.
Regards Grandpamac.

For what its worth, GRT would suggest your somewhere around 10k psi over saami max pressure to get that velocity with the 19” barrel.

McNotty pointed out “no need for superformance” but the reality is loads doing those sorts of speeds using 2208 are without a doubt overpressure no matter which way you look at it, just because theres “no pressure signs” doesnt mean it isnt there. Theres no free lunch when it comes to gaining velocity, you either do it by raising the peak pressure, or extending the pressure curve without increasing the peak, therefore pushing the projectile for a longer duration, switching to a slower magnum powder like superformance being the latter option. It seems alot of people are quite comfortable using some tough brass and pushing things past what the manufacturer deems the safe point. Either that or they just dont realise whats going on and use the “i must just have a fast barrel” excuse

Comparing apples with apples, going to the same 10k psi over saami max with superformance would land you around 2700fps, all else being equal, or ~ 2580fps at saami limits.

Originally Posted by 6.5 CRD

For what its worth, GRT would suggest your somewhere around 10k psi over saami max pressure to get that velocity with the 19” barrel.

McNotty pointed out “no need for superformance” but the reality is loads doing those sorts of speeds using 2208 are without a doubt overpressure no matter which way you look at it, just because theres “no pressure signs” doesnt mean it isnt there. Theres no free lunch when it comes to gaining velocity, you either do it by raising the peak pressure, or extending the pressure curve without increasing the peak, therefore pushing the projectile for a longer duration, switching to a slower magnum powder like superformance being the latter option. It seems alot of people are quite comfortable using some tough brass and pushing things past what the manufacturer deems the safe point. Either that or they just dont realise whats going on and use the “i must just have a fast barrel” excuse

Comparing apples with apples, going to the same 10k psi over saami max with superformance would land you around 2700fps, all else being equal, or ~ 2580fps at saami limits.

Max isn't a brick wall that everybody runs into at the same place. If I had over 70k psi, there would be signs no matter what brand of brass.

Originally Posted by John Duxbury

Max isn't a brick wall that everybody runs into at the same place. If I had over 70k psi, there would be signs no matter what brand of brass.

I know i have personally been up over 70k and the brass has shown no signs of pressure at all, hence why anyone that has a thorough understanding of internal ballistics will tell you "pressure signs" on brass is a terribly unreliable way of judging pressure.

Where would you suppose you are getting your extra 100fps from then if not extra pressure? You have a given set of metrics as far as barrel length, propellant characteristics and projectile weight. Im not trying to be a dick, genuinely interested