Model 7 7mm08 150gn eldx load development

So finally back in my happy place at the loading bench.

I procrastinated long and hard about what pill/powder combo to use I my model 7 7mm08, there were a few unique challenges for this rifle.
1 it has a short barrel at 17" (so should I use a faster powder ?)
2 it has a short magazine being a model 7 (should I use lower bc flat base pills? )

Ultimately there wasn't much choice powder is sparse at best and that's unlikely to change, pills well alot of the good performing flat base pills are already rocking horse shit (120gn nbts, 140gn nbts most of the barnes offerings).

I procrastinated too long and was left with little choice so I took a gambe and went all in buying 3 boxes of 150gn eldx and 1.5kg of ADI 2209 the only reasonably suitable powder I could lay my hands on.

I was a little skeptical about using 150gn eldx (a relatively long high bc pill) in such a short action, I was however encouraged by the fact that the hornady precision factory ammo shot under an inch in my rifle and was seated deep enough to be mag fed.

Here's what half a day of case prep looks like.......

Attachment 173151

Attachment 173153

100 cases sized, prepped and primed- charge ladder weighed out ready to.seat.....

Quote:

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Originally Posted by dannyb

So finally back in my happy place at the loading bench.

I procrastinated long and hard about what pill/powder combo to use I my model 7 7mm08, there were a few unique challenges for this rifle.
1 it has a short barrel at 17" (so should I use a faster powder ?)
2 it has a short magazine being a model 7 (should I use lower bc flat base pills? )

Ultimately there wasn't much choice powder is sparse at best and that's unlikely to change, pills well alot of the good performing flat base pills are already rocking horse shit (120gn nbts, 140gn nbts most of the barnes offerings).

I procrastinated too long and was left with little choice so I took a gambe and went all in buying 3 boxes of 150gn eldx and 1.5kg of ADI 2209 the only reasonably suitable powder I could lay my hands on.

I was a little skeptical about using 150gn eldx (a relatively long high bc pill) in such a short action, I was however encouraged by the fact that the hornady precision factory ammo shot under an inch in my rifle and was seated deep enough to be mag fed.

Here's what half a day of case prep looks like.......

Attachment 173151

Attachment 173153

100 cases sized, prepped and primed- charge ladder weighed out ready to.seat.....

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Interested to here how your ladder goes I'm doing one with 2208 in a 20" Tikka.

Sent from my CPH1903 using Tapatalk

I went 150gn eldx as I've had a flawless run with them in several 270 cal rifles win and wsm at 145gn so I figured chances were the slightly fatter heavier cousin would also perform well.
Pretty much the factory ammo gave me a good start point as the mag was only a couple thou longer than the ammo.
It shot well so I started there at 2.125" ogive length.
I started my charge ladder with three rounds at each weight starting at 44gn going up.in .5gn steps to 46.5gn which is 1gn over book max.
I was quite surprised when I loaded my lowest charge that I could feel that familiar crunch of a lightly compressed load....hmmm this doesn't bode well I thought.
Anyway I continued crunching my powder right up to 46.5gn.

Went to the range late afternoon, shot 3 factory rounds to check and yup shooting as expected and at the expected velocity.

I was expecting a little more velocity but then this is my first foray into short barreled rifles so a bit of an unknown.
Anyway I'll show the results of my velocity ladder and it should be pretty obvious which load I'm gonna use....
No target pics as they are still at the range but also I shot them pretty quick to get done before the light faded.
Best group under 1 inch and only horizontal deviation (most likely shooter) with a velocity spread of 3fps.....yup that'll do :thumbsup:
Goes to show, good consistent loading practice and case prep will give you good results.
I'm going to load up 6 more tomorrow to confirm what I already know before pulling out the stops and loading 100. Job done ✔

Attachment 173158

Velocity was less than expected but at 2576fps I'm happy that's plenty enough for dead reds out to plenty far enough.

I run 140gr NBTs in my 15" barreled 708. Running Cfe223. Giving 2740 fps.

They work pretty well out to ranges well past where im likely to be using a 15" barreled bush gun.

Quote:

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Originally Posted by GWH

I run 140gr NBTs in my 15" barreled 708. Running Cfe223. Giving 2740 fps.

They work pretty well out to ranges well past where im likely to be using a 15" barreled bush gun.

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Yup and I could literally get my hands on 1 box then likely no more until who knows when....that's why I went eith the eldx at least I could buy 3 boxes and re stock should be less of an issue

So an interesting quandary has arisen......:o
It has been suggested that in the short barrel I may see better velocity with ADI2206h, I have access to about half a bottle but there is no load data that I'm aware of ?
I was thinking I might load a ladder up starting at 38gn going up to 39.5gn as a bit of a test....anyone else got any data or able to feed that into quick load for projected results ?

Had a quick look at 308win data for same weight pills and that would suggest a starting load of 40gn and max of 45.5 would it be safe to assume similar with the 708 ?

Also I'm not that thrilled with the federal brass and considering "biting the bullet" and investing in lapua brass whilst I still can, is this likely to vastly effect my loads ? (Should I stop and wait till I have new brass and start again ?)
Thanks in advance :thumbsup:

yip

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Originally Posted by Gibo

yip

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is that in relation to the brass or the 2206h load data question?

I was just being an arse, you may find out of the rifle at least likes the projectiles but if you plan to change brass and powder i'd wait before going much further.

At the end of the day (in the words of @R93) do what you want, you will anyway :D

If you're getting lovely little groups and a 3fps spread with Federal, what have you got to gain?

Quote:

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Originally Posted by dannyb

So an interesting quandary has arisen......:o
It has been suggested that in the short barrel I may see better velocity with ADI2206h, I have access to about half a bottle but there is no load data that I'm aware of ?
I was thinking I might load a ladder up starting at 38gn going up to 39.5gn as a bit of a test....anyone else got any data or able to feed that into quick load for projected results ?

Had a quick look at 308win data for same weight pills and that would suggest a starting load of 40gn and max of 45.5 would it be safe to assume similar with the 708 ?

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Greetings @dannyb,
First and most important no it is not safe to use .308W data for the 7mm-08. Pressure will be much higher. I did a quick check on data for AR2206H 40.5 grains with 150 grain HPBT. Using a reduction of 30 or 25 fps per inch of barrel shortening suggests that AR2206H will come up short at 2,500 and 2,535 fps respectively. Lastly using the 30 fps per inch reduction suggests a velocity of 2,520 fps for your 45.5 grain load of AR2209. You are getting about 50 fps more than that. The Hodgdon data pressure is expressed in CUP (copper units of pressure) which suggests that the data was worked up in the 1990's. About 2002 the speed of AR2209 was increased hence your higher velocity and pressure. I reported on this some time back chronographing different lots of AR2209 in my 6.5x55. This would suggest that your additional 50 fps of velocity would put you about 1 grain over book max for the later AR2209. It looks like a good load none the less.
Regards Grandpamac.

Quote:

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Originally Posted by Pommy

If you're getting lovely little groups and a 3fps spread with Federal, what have you got to gain?

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Very fair call.....Sometimes a reality check is what's needed....I do love to tinker, sometimes to my detriment.
There is nothing wrong with the 2209 groups thats for sure I guess it was just too easy.
I am not a fan of the federal brass due to the primer pocket inconsistencies, its all once fired but some felt a lot looser than others.

Quote:

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Originally Posted by grandpamac

Greetings @dannyb,
First and most important no it is not safe to use .308W data for the 7mm-08. Pressure will be much higher. I did a quick check on data for AR2206H 40.5 grains with 150 grain HPBT. Using a reduction of 30 or 25 fps per inch of barrel shortening suggests that AR2206H will come up short at 2,500 and 2,535 fps respectively. Lastly using the 30 fps per inch reduction suggests a velocity of 2,520 fps for your 45.5 grain load of AR2209. You are getting about 50 fps more than that. The Hodgdon data pressure is expressed in CUP (copper units of pressure) which suggests that the data was worked up in the 1990's. About 2002 the speed of AR2209 was increased hence your higher velocity and pressure. I reported on this some time back chronographing different lots of AR2209 in my 6.5x55. This would suggest that your additional 50 fps of velocity would put you about 1 grain over book max for the later AR2209. It looks like a good load none the less.
Regards Grandpamac.

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Was hoping you'd chime in :D thanks you have re-enforced what I probably already knew subconsciously....

Quote:

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Originally Posted by Gibo

I was just being an arse, you may find out of the rifle at least likes the projectiles but if you plan to change brass and powder i'd wait before going much further.

At the end of the day (in the words of @R93) do what you want, you will anyway :D

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Will definitely be changing brass but likely not powder....ironically I was talking to Dave last night :thumbsup: