Results 30-06/30-06 Ackley Improved /30Gibbs

[fps plus]

I have a few results to share
This by no means a scientific experiment but my results . My ball my game my rules .

I used a Ruger M-77 30-06 with 22 inch barrel (factory). A factory box of International ammo with 180 gr x bullets to start. Components Federal 215 primers , Sierra 180 gr spritzer (2150) H4350,H4831sc,Imr 4831 and Re22.The same brass (Remington ) from the box of factory ammo was used for all cartridges. Sierra 180 used for all test except for the original firing of factory ammo. Seating depth for all loads 3.340 which is SAAMI specs. Used a Chrony.

I don't know what the pressures were but tried to stay in a range when primers and web expansion were indicators ,backing of slightly when they seemed high.

I am not going to list the actual charge weight of loads , just the highest velocity.

VELOCITIES;
1 -- 30-06 std Factory 180 2683fps

2--30-06 std handload 180 sierra 2731fps

3--30-06 Ackley chamber firing the 30-06 factory (1) 2655fps

4--30-06 Ackley chamber firing the same 30-06 std handload( #2) 2762fps

5-- 30-06 Ackley firing Ackley brass 2906. fps

6--30 Gibbs using formed 30 Gibbs brass 3000fps



The Ackley is easy to form by simply firing standard ammo in the
Improved chamber . The Gibbs I formed from the Ackley brass and fire form by jamming the bullet into the lands and Trailboss powder. No brass was lost in either chambering .

The #6 load is a little warm and I probably would back down a little but I think 2975fps is doable with no issues.

It appears bolt thrust is quite different with the straighter wall cartridges .I had a load that blew primers but bolt lift was not an issue.

note I have faster velocity firing my standard handload in the Ackley chamber than in the standard chamber ?????????

[bat119]

Thanks for sharing your experiment
Its interesting there was little gain between the Ackley and the Gibbs I thought it would be more. A 10% gain over a standard 30-06 is still a good result.

[fps plus]

Remember this is a 22 inch barrel.

[Don_Parsons]

Awesome project fps, always nice to see these older chamberings on the go.

Don

[fps plus]

I tried to keep my opinion out and just show results. I found it quite interesting .

From a gunsmithing perspective its easier to cut a Gibbs chamber than an Ackley ,as the Ackley should have the barrel set back before re-chambering .Which is one more step.

[skidderman]

Interesting. In a remington 700 30-06 I was able to get 2780 to 2800 in a 22" barrel. 180 grain nosler accubonds with a stiff load of RL22. Chrono may or may not be accurate. I inquired with a gunsmith once about doing an ackly & he talked me out of it. In a similar rifle I had previously it was approx 50fps lower. Chasing velocity along with accuracy is certainly a challenge.