Thread: 7mm08 168vld data

I like berger bullets and have wanted to see how these shoot for a while now.
There isn't much info out there but I found book max was expected to be around 40gn from a couple sources.

Alpha brass
Fed 210m primers
2208
168vld hunting

17" barrel
Loaded just over 3" c.o.a.l

**expect higher pressure if loading saami length**

Quick ladder to stay safe:
38gn 2325
38.5gn 2350
39gn 2377
39.5 2413
40gn 2455
40.5gn 2458
41gn 2512

About 50fps slower than anticipated. There is a lot of empty case capacity left and no pressure signs. I honestly believe these will safely run at 2600fps.

Here's the 41gn case



The ladder printed 6 into a neat group with one outlier. Magneto speed attached to suppressor.

I fired 10 rounds of 40gn to check accuracy. I'm pretty happy with that especially given an intermittent crosswind.



This load is holding the same zero as my Eldms so I'll stick with a slow and accurate load for now.

Even 2455fps at the muzzle still holds 1600fps past 700m.

More data will follow as time allows.

41.5 - 2544fps
42. - 2556fps
42.5 - 2600fps

No ejector stamps but primers are now flat. I've measured the case heads before and after and they expanded 2thou. Alpha suggest this reflects a sustainable load that's not gonna trash the brass.

2600 from a 17" barrel. Happy days.

That’s cool might have to try them my self just cause

Give staball a hoon and post the results

What leads you to believe that this load is running 50fps slower than expected please? I would be more inclined to the view that you are seeing 100fps more than expected, which inevitably means you must be generating higher peak pressures than expected from some variation in the powder, case capacity etc. The ballistic calculators will tell you that closer to 75kPSI peak will result for a 2600fps MV from only a 17" barrel for 2208. It would be remiss of me to read your posts and to then not advise caution.

Appears 08 is better than staball and reloader26 better again but you run out of room to fast

Nothing scientific bro, warm charge got me 2550 with 162projectiles so I anticipated a warm charge (40gn) with a heavier projectile would get me 2500fps.

Once I got closer to 100% case fill it came into its own for sure.

Greetings @SPEARONZ,
I have to agree with @Puffin In that your loads are dangerously over pressure. You are 2.5 grains over the Hodgdon book max of 40 grains for the similar Sierra 168 grain HPTBT suggesting .pressures way over max. When you look at your chronograph results things are even worse. You should expect a velocity loss of around 200 fps with your 17 inch barrel from the 24 inch book data but you are recording only 85 fps. This could be your components giving higher velocity and pressure, wrong powder loaded or chronograph error. Looking at case heads and primers is a notoriously unreliable means of guessing pressure. Measuring case heads is difficult and requires special kit to get right and more recent testing against electronic pressure measurement equipment have questioned its reliability. From memory expansion of 0.002" would suggest very high pressure. If you continue to load at that level the happy days may not last that long.
Regards Grandpamac.

Yea fair points all around thanks team.

Greetings again,
Just some notes on measurement of case head expansion to guess pressure. I first saw this mentioned in an article by Bob Hagel in the mid 1980's. The idea is that by measuring the expansion of the case head you can estimate pressure. I fiddled with it for a few years but with the need to use a new case for each method and other difficulties I abandoned it. Fast forward to 2020 and an article by Rick Jamieson in Handloader found that the relationship between case head expansion and pressure was nowhere as linear as was thought. Rick checked the expansion against pressure measured with a strain gauge. Rick suggested that the best approach is to use the pressure tested data available today. I would go a little further and suggest using the chronograph is the best way to check that your components give the same pressure as the data is the chronograph.
Regards Grandpamac.

Spear did note he was loading long at 3" rather than the 2.8" sami standard, this will lower pressure or allow for more powder.
Still need to run through a model ie GRT etc.
Z

So yes this suggest you are hot. GRT
Suggest 41gr of 2208 is about as hot as you should go for an estimated velocit from a 17" barrel is 2436fps.
Z

Yea will stick to 40grains, does all it needs to do. Funnily enough the original Intent was to find precision not speed.

There are a few things online about alpha not showing the typical pressure signs but they recommend measuring cases pre and post firing to gauge it. I've found GRT smack on most of the time but with heavies it's been a bit hit and miss. Eldx for example was predicted to about 5fps while eldm was way off.

Bergers again seem to shoot fast and loading long skews the data further.

Probably a good lesson in here somewhere about loading for ego.

Originally Posted by SPEARONZ

Yea will stick to 40grains, does all it needs to do. Funnily enough the original Intent was to find precision not speed.

There are a few things online about alpha not showing the typical pressure signs but they recommend measuring cases pre and post firing to gauge it. I've found GRT smack on most of the time but with heavies it's been a bit hit and miss. Eldx for example was predicted to about 5fps while eldm was way off.

Bergers again seem to shoot fast and loading long skews the data further.

Probably a good lesson in here somewhere about loading for ego.

My alpha brass showed pressure pretty typically with 150lrab but same charge with 150eldx is 100fps faster and not showing the signs must be in the construction I guess

Originally Posted by ZQLewis

Spear did note he was loading long at 3" rather than the 2.8" sami standard, this will lower pressure or allow for more powder.
Still need to run through a model ie GRT etc.
Z

The difference from loading to a longer length and increasing the powder charge to fill the space is very small as is the extra velocity from improved cases. There is a method for calculating this so I ran the numbers. It works out to an additional 17 fps. Many claim large increases from loading long or AI cases but most of this comes from more pressure.
Regards Grandpamac.