I've heard of a few Sako 85 blowing apart due to a ruptured case. Since I'd very much like to have a Sako 85, this of course got me thinking twice.

Check here: http://www.opticstalk.com/sako...w-up_topic19930.html







Even if the final diagnostic is not out on that particular one, it looks just like a ruptured case problem. Which should NOT be a problem, except that, from what appears when looking at the 85 action:

- There is no relief hole/holes in the action, just out of the chamber, allowing gases to escape and reducing the pressure buildup in the other escape ways (which are not properly designed in this case)

- There is no relief hole in the bolt, allowing gases from a ruptured primer or other to vent out instead of building pressure inside the bolt body

- The main escape ways seem to be along the left rail, and down the magazine. There is no escape gap between that rail and the bolt body, except a faint line towards the magazine. Pressure will build up against the bolt shroud. Result, blown magazine, stock, and possibly bolt shroud.


All the points above are easily addressed at the factory:

- Drill a hole in the receiver, in the lugs recess (due to the 60deg geometry, that may end up low on the right side for a RH rifle)

- Drill a hole in the bolt, venting in the left rail

- Mill a recess along the top of left rail, just ahead of rear bridge, about 25mm/1" long ("à la" Mauser 98 for example). That would allow gases in the left rail to vent out.

None of the above is rocket science, none demands special tooling, and none is expensive to implement.

Now, I'm not sure that a manufacturer would modify a design in a way that implies that it was not safe or sufficiently safe prior to the mod, unless they go for a full recall...

But all the above should be easy to perform in-house by anyone with basic gunsmithing skills, and appropriate tools.

What do the experienced gunsmiths and gunmakers on the forum reckon?

I've noted this issue with the new Browning X-Bolt rifle. It has no gas venting features at all. In fact, there is a lug cutout at 12 o'clock that would blow gases straight back at the shooter's forehead.

Any mods you make to your action would certainly void any warranties made or implied by SAKO. Check with their tech dept. to see if your mods would affect action integrity. I see no issues with your ideas and they certainly would be endorsed by the late Frank de Haas. You might even send them those pics to emphasize the point!