Minimum Shoulder height??

T

thekubiaks

New member
I'm still learning to chamber my own barrels so please be gentle.

I have a BAT M action (1.125" x 16tpi) I would like to chamber a .338 Lapua Magnum in a 30" Heavy Varmint contour. I prefer Kriegers and Bartlein barrels but the barrel manufacturers only list shanks of 1.250" in that contour. I think I need more shoulder and therefore a bigger shank.

Two issues I am having,

1) what is the minimum shoulder height you'd recommend??

and

2) I can't seem to find a barrel manufacturer that will cut a heavy varmint contour in any shanks > 1.250"

Thanks for the replies.
 
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Not sure what you are asking for. Your action is threaded smaller than the blanks provided - simply turn the largerblank down to fit your action. perhaps it is just terminology, but don't understand the problem. Are you looking for a blank of overal diameter larger than 1.25" for some reason?
 
thekubiaks,

I have the same action.....and the same problem. I was told by many people that the 1.250 barrel was fine for the 1.125 shank as long as you used a recoil lug.

I was also told by some that it would be ok to tighten right to the action "if it was done right."

I opted to get the 1.450 shanked blanks but since this is a large rifle I haven't tried to get a HV taper only Heavy Palma.

Sorry to be of no help

al
 
Minimum Shoulder height

Thanks for the replies. alinwa, you and I are on the same wavelength. I will have to ask around about recoil lugs and possibly a 1.450" shank. Supposedly it is not that big a deal to order a 1.350" or 1.450" shank and a straight taper to whatever barrel length and muzzle dimension you desire.
 
Just thinking about this and not knowing Jack about engeneering I would opine that it doesn't require a whole lot of shoulder to keep a barrel straight as long as there is a fairly tight fit between the tennon and action screws. I would think the combined fit if the threads and the surface area of the shoulder all combine to make the fit.
 
I just finished chambering two barrels for a BAT "M" action...the barrels were 1.250 straight and both had adequate shoulder for contact with the action face...I know that a LV contour will not give enough shoulder, but the 1.250" works well...



Eddie in Texas
 
eww1350 said:
I just finished chambering two barrels for a BAT "M" action...the barrels were 1.250 straight and both had adequate shoulder for contact with the action face...I know that a LV contour will not give enough shoulder, but the 1.250" works well...



Eddie in Texas
Click to expand...

Thanks for the replies. From an engineering standpoint, I was thinking that there was some minimum amount of shoulder contact because of the rearward shear forces when the round fired. A 1.250" shank would have 1/16" contact all the way around the barrel circumference with the BAT M action (1.125" x 16 threads, 1.550" OD). I suppose the stress of a .338 Lapua Magnum might require a little more shoulder?? I was kind of "fishing" for a consensus on minimum shank size I should use.
 
I think what you are asking doesn't exist. I am pretty sure that the 'HV' contour specifies 1.25 at the shank. Therefore the bbl maker won't have a 'HV' blank with a shank larger than the spec. Order the shank dia you want and the muzzle dia you want and let them taper it to suit.

I DO think you are on the right track wanting more surface on the torque shoulder. You are making a big boomer and you will want to torque the bbl to at least 125 ft lbs. I would worry about the 1.25 dia shank fretting or otherwise damaging the front face of the rec or recoil lug when you torque it down and possibly when firing.

I have a Hall RF that has a .750 thread dia and an .850 bbl. which gives about .050 of a torque shoulder surface. It only gets torqued to app 40 ft lbs so it works fine.

Good luck.
 
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