To Ackley Improve the 338 Lapua or not?

[Justin Crossley]

Hey guys I just bought a new Christensen Arms MPR in .338 Lapua and am thinking of having my gunsmith Ackley it for more velocity. I plan to shoot the Berger 300 grainers in it. For those who have had both, what do you think?

 

[Msowa]

with the end goal of shooting 300gr's? then yes...straight up 338lm with 300gr is anemic at best. Suspect that's not a 30" tube either so another reason to do it.

 

[Justin Crossley]

with the end goal of shooting 300gr's? then yes...straight up 338lm with 300gr is anemic at best. Suspect that's not a 30" tube either so another reason to do it.

I've got some ceracoat plans I need to talk to you about too. Thinking Kryptek Raid on all the metal?

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[Broz]

Do it. Only use Lapua head stamped Brass. Use VV N-570 , 300 Bergers and never look back. And yes I have both to compare. The AI is worth 150 plus fps.

Jeff

 

[Msowa]

I've got some ceracoat plans I need to talk to you about too. Thinking Kryptek Raid on all the metal?

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Send it!

 

[deerkiller]

you'll get way less case stretch as a side benefit when you Improve a case also AND, if done correctly you can shoot fireform loads for hunting or "serious" target work too

 

[wind gypsy]

straight up 338lm with 300gr is anemic at best.

Hell, and I'm too anemic to deal with the oomph of a 338 LM shooting 300's in a hunting weight rifle.

 

[Justin Crossley]

Okay guys the rifle is at the gunsmith for re-chambering.

The magazine measures 3.76" inside. What are you guys running for an OAL with 300 grain bullets? I'm hoping I have enough space....

 

[Broz]

Okay guys the rifle is at the gunsmith for re-chambering.

The magazine measures 3.76" inside. What are you guys running for an OAL with 300 grain bullets? I'm hoping I have enough space....

My 338 Terminator round seated on the lands utilizing all case capacity with a 300 Berger is 3.907" OAL. Keep in mind this is a single feed. So it seems reasonable to sink the bullet another .150" ~.170" and still ok. You will just loose some case volume so may need to run with the next faster powder, however I would try 570 first and feel it should be ok.

 

[Broz]

PS: to add. With the capacity loss I would NOT +P the throat.

 

[Broz]

Justin, my last 338 AI 40* maxed out at 99 gr of VV N-570 under a 300 Berger and was running right at 3K from a 30"

This was max, so as always work up. I just thought this info might help you with your case capacity and OAL question. For reference. I have loaded up to 112 gr in the Terminator +P at 3.907" OAL. So I think you will be close but ok on capacity.

Jeff

 

[Justin Crossley]

Sounds like my MPR is just about ready for coating! I leave for Alaska in a couple days so I won't be shooting it until the middle of July but I'm getting excited none the less.

 

[Justin Crossley]

Getting closer! I just got these photos from Sowa.

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[longbarrel]

None of the Ackley improved rounds I have seen data on gave much velocity from the slight increase in case volume. Ackley typically firewalled the pressures and that gave more. If you want to push 275-300 grainers fast, you really want the 338-378 Wby case, and a long barrel. See Rifle #53 (Sep-Oct. 1977) and Handloader #141, Sep-Oct 1989. Rifles used for those articles had 26" and 26.8" barrels. A 31" barrelled rifle with the same loads gave about 200 fps more with those very slow powders. The article in HL141 showed max velocities of 3088 for the 275 Speer and 2998 fps for the 300 Barnes with the 26.8" barrel.

 

[Broz]

AI on a 338 Lapua with 300 Berger and a 30" barrel is worth 150 fps over a standard 338 Lapua 30" with N-570

Add a +P throat and get an additional 100 plus fps putting you over easily 3100 fps with a 30" barrel and a 300 gr Berger

 

[Ryan Avery]

Looks great!


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[Justin Crossley]

I have both rifles dialed and ready to go. I'm shooting the same load in both of them and seem to be getting good accuracy. The load is 99 grains of Retumbo, CCI Mag Rifle primers, and Berger 300 Grain Elite Hunters. My buddy's rifle is running 2870 fps and mine is at 2865 fps so our ballistics will be identical. So far I'm really happy with how they turned out. Hopefully, we'll have some bear photos in a week or so.

 

[elkguide]

Time to spill a little blood!

Looking good!

 

[Broz]

That thing looks great and is going to flat paste a bear. You have seen what a 300 Berger does to a bear at 1702 yards. LOL

 

[Quicksilver]

That thing looks great and is going to flat paste a bear. You have seen what a 300 Berger does to a bear at 1702 yards. LOL

No, but I have seen them on a bear at 500yds and almost made me want to sell everything and build a dedicated setup to launch them! I settled on a 300 norma improved instead. Still have an itch to get something going with a 300 berger though...very impressive stuff.