CZ 550 FS Ackley conversion

[tcsnake]

Hi there, I have a CZ 550 FS in .243 and was wondering what steps would have to be taken to convert it to .243 Ackley improved. Is this even possible? I am not a gunsmith, but I understand the basic working principles of a rifle.

Thank you

 

[CypherNinja]

Generally, you would just have a gunsmith ream the chamber.

 

[Jim Watson]

A PROPER conversion to Ackley Improved calls for setting the barrel back a turn so that the new chamber will be of minimum headspace and will fireform from factory loads without stretching. More trouble than it is worth to me, especially with some of the powders now available.

 

[rcmodel]

+1

The AE's were much more impressive before everybodys dog had a chronograph, and pressure tested loads became common in reloading manuals.

rc

 

[eastwood44mag]

Do-able, but a waste of time.

You'll only gain maybe 80-100 fps with the AI, but you'll need to add roughly 7 more grains of powder to do it. The .243 Win is almost at maximum effective case capacity.

Get a copy of P.O. Ackley's Handbook of Shooting and Reloading before proceeding. I like AI cartridges, but only if they're practical, and the .243 Win isn't a good candidate.

 

[Pokyman]

For the Ackley conversion to be done correctly, the barrel must be set back and rechambered. Where as the standard calibers use go and no gages, the Ackley chambers use the standard go gage as the no go gage. The go gage for the ackley is slightly shorter than the standard go gage. With the ackley chamber being slightly shorter than standard, 243 ammo can be fired in the improved chamber to be fire formed.
Actual performance improvement over the standard 243 will be minimal with standard weight bullets and a 22 or 24 inch barrel.

 

[Alpacca 45]

Just to add to what the guys have already said;

Because the Ackley case uses a sharper shoulder angle, the only place that factory case can headspace is where the shoulder meets the neck.

Ackley realised that he had no control over this dimension in factory rifles, hence the need to set the barrel back and re cut the chamber to get this dimension exactly right.

A CZ is a comparitively easy rifle to do this sort of work in, as it uses the mauser 98 type inner collar in the receiver, so the case head protrusion is controlled by the receiver and there are no cones or extractor grooves to re cut.

Where the Ackley improved cases come into their own is in re using a shot out barrel, for example if you have a heavy enough barrel in .308 which has a worn out throat, .30-06 Ackley improved has a straight enough body that it will totally clean out the .308 chamber, and take most of the eroded portion of the throat and rifling, giving you several thousand rounds of new life.

With 6mm, you probably wouldn't benefit from putting an 06 sized case behind it.