Bat 3 lug

[Guest dasherman]

Has anyone got a barrel tennon drawing for a BAT 3 lug action , .308 b/face with a coned bolt? Bat are not answering phone,fax or emails and I cannot find it on their website. You would think it would be simple to supply a drawing with a new action or at least publish it on the net.

[baldie]

cant help you there buddy, but i,ll bet vince has one, i,ll pm you his addy.

[1967spud]

ive trawled google for a while mate but in this case google isn't your friend

[Ronin]

Tenon is 1.062"x18tpi (taken from BAT site), I measure overal tenon length to roughly end of threading within action / just slightly deeper than the measurement from action face to bolt face.

 

Measure angle of bolt cone with protractor and set compound to same, then start to form cone in barrel tenon, keep test fitting untill action screws into action face and you can close bolt.

 

 

(Well thats how I have done my own BAT)

 

Hope that helps.

[Guest dasherman]

Thanks for the quick replies, I can work it out it just seems stupid they dont supply them. Kelbys do and I know the cone clearance is fairly critical.

[Ronin]

The same happened with the RS action I used with the tactical rifle build - no dimensions.

 

 

I used the feeler guages to get the final clearance dimensions - sure you know what I mean, ,,,,

 

 

I went in +.005" deeper. When torqued up the clearance is possibly reduced to .004" maybe a little less.

 

It worked for me and similarly with the Barnard I built, which is also cone bolt.

[eldon]

Whats the benefit of a cone bolt design?

[Ronin]

Cone bolt design is supposed to allow or move the bolt into the centre line of the action / barrel chamber thus central firing pin strike and more importantly equal pressure on the bolt lugs - which stops action flex on firing.

 

Numerous target actions use this principle (BAT, Barnard etc) and it seems to work.

 

What benefit there is over a "normal" trued or precision made action is open to argument though.......

 

Just a different way of skinning the cat I guess.

 

This is a dummy barrel stub I made up when I first started machining, it shows the Barnard cone, the circular mark within the cone is from the very edge of the sako style extractor as I had made a minor error and not accounted for the .002" that it protrudes beyond the cone face.

 

The finished barrel does not have this mark I hasten to add

 

 

You can see on this example of a rem 700 bolt nose that there is no cone, so there is "potential" for the front of the bolt to move within the barrel bolt nose recess and not be perfectly concentric to the boreline.

 

 

Again, open to discussion as to how much this actually really matters in sporting rifles....

[eldon]

Cheers andy.

Like you say dubious advantages compared to a precision made action, it would be hard to prove one way or the other of any real gains but in theory the cone has it I suppose.