40x serial number with B

[fe1]

On a 40x 22LR what does the B at the end of the serial number designate?

 

[MrG52D]

It is the second generation of the 40X, ( 1964 I think ) a few changes were made, then after that, it was the 40XR.

 

[Dusty Stevens]

It will have the 700 swept back bolt handle instead of the 720 series straight handle

 

[flatlander]

Those are the major differences between a 40X (which was based on the M721) and the 40XB, which was based on the M700. I bought a couple of 40XBs and one 40X from the CMP in 2004-2007, and IIRC, there was some minor differences in the gas shield of the bolt also. The 40X I bought had the std weight bbl, which was much lighter than the heavy barrels on the 40XBs. The 1960 edition of Shooter's Bible lists the 40X as available with both the std wt & hvy wt bbls; I don't recall whether the CMP had any hvy wt 40Xs for sale at the time when I ordered mine, but I can tell you that hvy bbl's on the 40XBs were 'truck axle' heavy. I shot one of mine with coat & sling quite a bit, and though it was very stable in prone, I think it'd have been a bear in offhand & kneeling, while the 40X std wt was light enough to have worked well in 3-P shooting.

 

[fe1]

Those are the major differences between a 40X (which was based on the M721) and the 40XB, which was based on the M700. I bought a couple of 40XBs and one 40X from the CMP in 2004-2007, and IIRC, there was some minor differences in the gas shield of the bolt also. The 40X I bought had the std weight bbl, which was much lighter than the heavy barrels on the 40XBs. The 1960 edition of Shooter's Bible lists the 40X as available with both the std wt & hvy wt bbls; I don't recall whether the CMP had any hvy wt 40Xs for sale at the time when I ordered mine, but I can tell you that hvy bbl's on the 40XBs were 'truck axle' heavy. I shot one of mine with coat & sling quite a bit, and though it was very stable in prone, I think it'd have been a bear in offhand & kneeling, while the 40X std wt was light enough to have worked well in 3-P shooting.

Yes my CMP US marked 40x had the HB, Target Stock with sight blocks.
I converted it to a ARA BR rig and now converting it to a Sporter.
I’m wondering what style of barrel sights would be correct for a commercial B suffix SN for the era?