7mm - 08 Ackley Improved information Blog!

[plumbs7]

Hi All , I have got it sorted ( I hope)! Was tight neck syndrome! Some of the necks were way to tight nearly .312 in a .312 neck ! Thus grabbing the bullet and creating a velocity spike .

Also learnt not to leave powder in the hopper as velocity was down 30 plus Fps !

Final load is and please use with caution. Fireformed lap 308 brass lr fed primer is 46.7 gr 2209 behind a 180 hybred pill!

Accuracy is outstanding ! I gues we will see how it goes at Ipswich!

Regards Graham.

[Quick]

You want around 3-4 thou neck clearence. My 7mm08AI has a 314 nk.

Your load seems about the same as mine. I run 47.3gr 2209 with 180gr VLD in Palma Brass so given that you usually need more powder in palma brass its close. Whats your MV?

[Steve N]

Shaun I will agree that they like 3-4 thou neck clearance. Any less and my 7-08ai gets very erratic.
What seating depth do you find best? I have been jamming 15thou but just recently found that the 180 vlds also like a 5 thou jump in my gun with the right load. My muzzle velocity is around 2730 but I am using AR2213sc not 2209.
Steve.

[plumbs7]

Yep I totally agree with 3-4 thou. But I don't have a type s die and collet . I just have a standard redding Ai standard die like Steve .so have to watch neck tension!
Mz is 2760 Fps ! It's a great little cartridge !
Regards Graham.

[Norm]

Graham,

Don't be afraid to give the 168gn Berger VLD a try.
They can be driven quite fast in this cartridge and hammer the cases a lot less than the 180's.

[Quick]

Or just use palma brass and get a serious amount of firings hahaha.

Ive got some 162gr Amax to try. The BC is awesome for the weight. Going to try them soon. I jam my 180gr VLD 10 thou. The jump also works but not as good as the jam.

[plumbs7]

Hi Norm , I'll give them a try sometime 168's.

Ok this little sucker , actually had 2 of them just under .312 netted 2820 and 2793 Fps . Not good , I've gone through my whole stash again and will check again when loaded! 308 was so much easier ! That's open I guess!

[Norm]

With my .284 and its .312" neck, I ran with .308" loaded case neck diameter.
Then when I went to a .315" necked chamber the old brass with its .308" loaded neck diameter shot just as good as before. So not sure if you need to go with minimum neck clearance. It seems to cause more trouble than its worth. It was handy though as I got just the right amount of neck tension with a standard set of FL dies.

I have a .311" neck in my 7-08ai and its a pain at times. The next chamber with my 7-08ai will also run a .315" neck. Less turning required and hopefully less issues with case necks as the brass gets older.

[Quick]

I chose 314 but could have gone 316 really. You just need to clean the necks up and thats it. But 314 does work for me with a loaded round of 310.

[plumbs7]

I know you are all getting sick of groups and also , why am I shooting of a Harris ! My front and rear rest are getting work done to them both.

Ok below was another group at 100m . The first 3 went through the same hole and the wind and myself stuffed the rest . But I'm over the moon with how this thing groups and recoils. F class macs aren't good of a bi pod. So it would seem things are working well! .314-.315 neck dia would be just nice if u r going to get one of these ! .312 is just marginal! Regards Graham.

[plumbs7]

I don't know if anyone is interested . But just to finish up the thread . On Sunday at Jandowae with the 7-08ai shot a BP of 125.7 at 800 yard. Yes it was windy ! About 2.5 minutes rht wind!
So very happy! The one that I dropped , was 12 o'clock high and I thought was me! But alas there was one case just under the .312 neck dia ! That was the first detail and was 5.1 mills elevation . Was a very clean barrel. But I ended up at 4.8 mills . Eg in the second detail as it fouled and the bullets were in the sun a little . Ballistically was getting 2820 Fps with very good accuracy !

In fact with a 5 mph full wind the 7-08 Ai using hybreds at 1000 yds 2770fps is only a 9 mm disadvantage to a .284 at 2820 Fps using vld's . That's what I worked from memory ! But I know it was minimal ! That is the 7-08 can possibly keep up!

Ipswich OPMis this Sunday , so we will tell! Hope the owner doesn't let the Gun down!
Regards Graham.

[Quick]

The lil 7mm08AI can keep up and beat the 284s for sure. I shot the MDRA OPM at Brisbane before the teams and got 4th against many a bigger 7mm rifles. They sure can be accurate.

[plumbs7]

The lil 7mm08AI can keep up and beat the 284s for sure. I shot the MDRA OPM at Brisbane before the teams and got 4th against many a bigger 7mm rifles. They sure can be accurate.

Hi Shaun, I'm sorry I wasn't there to meet all of u . Had to work! But yes I'm very impressed with performance of this little cartridge . Has inherent accuracy , will have excellent barrel life, heaps of brass and does it with a lot less powder . With 180's I'm now getting around 2790-2800 fps . I shot a 60.4 at 800 yes last weekend . But had a shocker in the second. Typical Dalby conditions . Was 2 steps behind the conditions!
But very , very happy and thank Norm and Steve for bringing this cartridge to light! I'll compete with it till the end of the year at local Opms .
Regards Graham.

[Norm]

Just to add to the knowledge base for this cartridge I will supply some more data.
The rifle I have has not lived up to my expectations as far as accuracy goes. It gets great velocity but I think my barrel is not the best going around.
So after getting back from Queensland I had 2" chopped off the end of the barrel to see if this would improve accuracy. So far I have not tried it for accuracy but I did a before and after velocity check to see just how much velocity I would loose going from a 32" barrel back to a 30" barrel.
This is what I found................

32" barrel. 168gn Berger VLD, 47.5gn AR2209, Lapua LR brass, BR2 primers, 2.400" OAL.
Average velocity 2879fps with a SD of 10fps.

30" barrel. Same load.
Average velocity 2864fps with SD of 2fps.

So not much velocity loss going back to a 30" barrel. Guess which length barrel I will be replacing this one with?

[williada]

Graham, your short range test predicted the lost shot at 12 o'clock. It was put there by the interacting harmonic frequencies which may or may not be linked to the neck thickness.

Norm, sort of confirms what we discussed. On Saturday, I will do some load development with mine having lopped off two inches.

For others, the powder has completed it work and groups can be subject to the sputtterings of its last breath as are the barrel harmonics. A tool like "Pressure Trace" can analyse this for you. David.