Hi Everyone,
I'm machining an aluminium block on which to bed a Tikka M590, and I'd just like a bit of input as to which area's it should be bearing on etc. I've posted a sketch, indicating the areas's which I think should be and a bit of my reasoning behind this but again I'm obviously open to suggestion's.
The M590 action from what I can gather is a forebear to the current production Tikka T3, and visually from the topside the two look very similar, However I've the feeling that the 590 has a smaller loading/ejection port. As for the underside I can't comment as I've not seen the bedding arrangment of a T3, but now they run an insertable recoil lug.
This will be an ongoing project: initialy the aim is to get it setup to the point that the viability of the used barrel can be tested. If I feel that the action lacks a sufficient bearing area, I'll unscrew the barrel and machine a reduced shoulder on which to sandwich a meaningfull recoil lug, a la Omark, M80 Angel etc.
Should the barrel prove too worn to group acceptably I may shorten it @ the chamber end by a little, cut and thread a new tennon and recut the chamber to move it closer to sharper lands (currently 30" of barrel).
If after this it still doesnt perform as intended I'll discard then procure a new barrel.
At the momment it's in .308 palma, I may look to go 6.5x284 or similar. Once I know what cambering will be proceeded with I can then look at magazine options (for the testing stages it will only have a shallow loading block sitting on top of the main aluminium billet).
RED AREAS DENOTE BEARING SURFACES
-FRONT ACTION SCREW-
Counter-bore the top of the hole for the action screw aiming for a 1:1 fit, over the button on underside of action. Perhaps by .015” relieve the front side of the counter-bore (between the action screw hole and slot for the new recoil lug. Ensure the boss/button bears evenly on the bottom of the counter-bore & horizontal surfaces surrounding it. Sandwiched recoil lug would be set to come into engagement, at the same instant as the button around the action screw does.
-MID SECTION-
Generously relieve the horizontal surfaces around the proposed magazine well. “Clearance is clearance”, but to make taking the cut worthwhile it might as well be .060” (1.5mm) in depth.
-REAR ACTION SCREW-
Apparently it is a massive mistake to have a Mauser styled front locking action, bearing recoil forces around the rear of the action (throwing shot’s), so accordingly I would run massive clearance on any semi-vertical surfaces in this area (you will notice the side walls of the protrusion on which the trigger assembly sits, has a draw/ taper angle to it). The flat horizontal surfaces of the rear area & the top of the protrusion (into which the action screw is tapped), are set so as they will be drawn into engagement at the same instant. Everywhere else will have generous full float i.e in the slot around where the trigger mech body will be.
I'm sure the way Tikka intended should be good enough*, however I suppose I cringe alittle looking at the size of that front round recoil lug. If I happen to machine all this and find that it doesnt shoot as intended (at which point I wont know if it's the fault of the barrel, bedding or operator) and to have to mess around set the bedding block up in the milling machine again etc, I just feel perhaps that I would be best done from the outset.
For mauser derivatives I thought it common practise to have the flat areas most of the way between the action screw relieved? could be wrong, but again open to suggestion.
*Tikka have subsequently gone to the inclusion of a recoil lug (or much larger one) in their T3's etc.
I'm machining an aluminium block on which to bed a Tikka M590, and I'd just like a bit of input as to which area's it should be bearing on etc. I've posted a sketch, indicating the areas's which I think should be and a bit of my reasoning behind this but again I'm obviously open to suggestion's.
The M590 action from what I can gather is a forebear to the current production Tikka T3, and visually from the topside the two look very similar, However I've the feeling that the 590 has a smaller loading/ejection port. As for the underside I can't comment as I've not seen the bedding arrangment of a T3, but now they run an insertable recoil lug.
This will be an ongoing project: initialy the aim is to get it setup to the point that the viability of the used barrel can be tested. If I feel that the action lacks a sufficient bearing area, I'll unscrew the barrel and machine a reduced shoulder on which to sandwich a meaningfull recoil lug, a la Omark, M80 Angel etc.
Should the barrel prove too worn to group acceptably I may shorten it @ the chamber end by a little, cut and thread a new tennon and recut the chamber to move it closer to sharper lands (currently 30" of barrel).
If after this it still doesnt perform as intended I'll discard then procure a new barrel.
At the momment it's in .308 palma, I may look to go 6.5x284 or similar. Once I know what cambering will be proceeded with I can then look at magazine options (for the testing stages it will only have a shallow loading block sitting on top of the main aluminium billet).
RED AREAS DENOTE BEARING SURFACES
-FRONT ACTION SCREW-
Counter-bore the top of the hole for the action screw aiming for a 1:1 fit, over the button on underside of action. Perhaps by .015” relieve the front side of the counter-bore (between the action screw hole and slot for the new recoil lug. Ensure the boss/button bears evenly on the bottom of the counter-bore & horizontal surfaces surrounding it. Sandwiched recoil lug would be set to come into engagement, at the same instant as the button around the action screw does.
-MID SECTION-
Generously relieve the horizontal surfaces around the proposed magazine well. “Clearance is clearance”, but to make taking the cut worthwhile it might as well be .060” (1.5mm) in depth.
-REAR ACTION SCREW-
Apparently it is a massive mistake to have a Mauser styled front locking action, bearing recoil forces around the rear of the action (throwing shot’s), so accordingly I would run massive clearance on any semi-vertical surfaces in this area (you will notice the side walls of the protrusion on which the trigger assembly sits, has a draw/ taper angle to it). The flat horizontal surfaces of the rear area & the top of the protrusion (into which the action screw is tapped), are set so as they will be drawn into engagement at the same instant. Everywhere else will have generous full float i.e in the slot around where the trigger mech body will be.
I'm sure the way Tikka intended should be good enough*, however I suppose I cringe alittle looking at the size of that front round recoil lug. If I happen to machine all this and find that it doesnt shoot as intended (at which point I wont know if it's the fault of the barrel, bedding or operator) and to have to mess around set the bedding block up in the milling machine again etc, I just feel perhaps that I would be best done from the outset.
For mauser derivatives I thought it common practise to have the flat areas most of the way between the action screw relieved? could be wrong, but again open to suggestion.
*Tikka have subsequently gone to the inclusion of a recoil lug (or much larger one) in their T3's etc.
