7X57 Ackley info

[Werewolf]

So, I am preparing to do this project for my brother. We have done quite a few rifles so far but this is the one he has wanted for a couple of years now. I LOVE my 280 ai that we built last and he figures it is his turn. Any body have any useful information or proven loads to share?
I know I know, the 7 mauser is a great round, and he has shot one for years, but that's not why we are here is it?

[bsekf]

The 7x57 AI is one of the great Ackley rechambers. Start with near max 7 mauser loads and go up....slowly.

[Savage6x284]

The 7x57 AI is great but if it's going into a long action (the only way really) then another .280AI would be preferable IMO.
A .243AI or .260AI on a short action would be sweet as would a vanilla (but awesome) .270 Winchester in a LA with a 24" tube would rock.

[Werewolf]

Yeah, we aren't doing it because I think it will be the absolute best, although I do think it will be a decent round. I am doing it because it is really what he wants. That's all it boils down to. Waiting on the barrel now.

[BillPa]

Yeah, we aren't doing it because I think it will be the absolute best, although I do think it will be a decent round. I am doing it because it is really what he wants. That's all it boils down to.

...and that's a goodnuf reason.

I ran this out to give you somewhat of an idea performance wise. I also made a few assumptions, 24" OAL barrel, 140 Sierra, seating depth, powder and etc....

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Bullet Type = 7MM 140-GR SBT GK SIERRA Bullet Weight = 140.0 grains
Bullet Diameter = 0.284 in Bullet Length = 1.140 in
Bullet BC = 0.418 Sectional Density = 0.248
Case Type = 7mm X 57mm Ackley Improved Case Length = 2.253 in
Full Case Capacity = 59.201 grains water Est. Overall Cartridge Length = 3.1281 in
Net Case Capacity = 54.964 grains water Bullet Seating Depth = 0.265 in
Rifle Type = Barrel Length = 24.0 in
Effective Barrel Length = 22.012 in Barrel/Case Volume Ratio = 7.3
Cartridge Temperature = 70.0 °F
__________________________________________________ ________________________________

Powder: RL-17
Calculated Powder Charge = 47.3 grains
Load Density = 86.0%
Charge/Bullet Weight Ratio = 0.338
Estimated Muzzle Velocity = 2681 ft/sec
Estimated Chamber Pressure = 43183 CUP
__________________________________________________ ________________________________

WARNING: For starting loads reduce calculated powder charge by at least 10%.


Load Table
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Load Charge Charge- Muzzle Chamber
Density Weight to-Bullet Velocity Pressure Notes
(%) (grains) Wt. Ratio (ft/sec) (CUP)
-------------------------------------------------------------------------------------
75 41.2 0.294 2335 32045 OK
80 44.0 0.314 2494 37157 OK
85 46.7 0.334 2647 42087 OK
90 49.5 0.354 2806 47199 OK
95 52.2 0.373 2959 52129 High Pressure
100 55.0 0.393 3117 57242 High Pressure


Bill

[Werewolf]

Thank you very much! That's some useful information. It will be a 24 inch barrel and 140 grains is the preferred bullet weight, but only testing will tell.