Bolt Clearence

[cutter]

In my opinion a very  important dimension is the
Distance  between  the cam follower and the front of
The bolt. I maintained a +/_ .001 tolerance for that
Dimension on all bolts.
The pin against the cam is solid, nothing can be
Done there.
Just one adjustment for all bolts.
About .004 clearence works well for my gun.

I didn\'t know that the cam follower pin in the bolt was the recoil lug. I thought the cocking ring at the point when the firing pin is released was the recoil lug so to speak. Head space was the measurement from that spot on the cocking ring to the rim of the casing.
bill

beginner is correct; the recoil lug is the highest point on the cocking ring.  The bolt guides should not be the recoil surfaces, they would soon tear out of the bolt as only a few threads hold them in the bolt sleeve (if using the RGG design).
Dick C. (gatguy)
 

[cutter]

I understand the theory, but how is there
 no recoil contact at the follower ??

[Dave]

The follower should not take any recoil, thats what the hump on the cocking rings is designed for. I made mine out of shock proof tool steel. If the followers took all of the recoil they would probably snap off or you would be changing them ever 100 rounds or so.

[cutter]

OK,  Dave & Gatguy agree on the theory.
     
     I’m asking anyone for the mathematical proof of the theory.

The \'followers\' should maybe be referred to as \'bolt guides\'; Their function is to guide the bolt thru the cam channels, not take the recoil, the \'hump\' has only one function...take the recoil.  I\'ve built several of these guns and the guides have never broken out.

Sorry, I can\'t help with the math.

Dick C. (gatguy)  :mrgreen:

[Dave]

Im sure the math is there on all the plans. A little more than I want to figure up!

[cutter]

Here’s how I see it.

The moment before the shear is released the follower is held against the
Cam by the force of the spring. At the rear of the bolt there must be
Clearance at the tall step for the bolt to pass. The recoil will generate
The same effect.

Drawing # 48-20  DETAIL C  (CAM FOLLOWER PIN)

[cutter]

I\'ve been reminded by two members that not all Gat builders have a CNC mill to cut the bolts.

Referring to the .250 pin soldered in place or .125 radius. ( My bolts have a .130 radius )


This area is for clearance and can easily be faceted on any mill.

 

[attachment=9469:Untitled-id=317.jpg]

Cutter, in the assembly instructions that came with the plans say to make some spacers that are .200 to put in between the two cams on assembly. That gives you .013 clearance for your cam followers to be clear of hitting the rear cam upon firing. The rear cap on each bolt has to be hand fitted to just rub the hump as it passes thus pushing the cam follower forward during firing. Without the recoil plate keeping the bolt forward, the cam followers and the rear cam will definetly take a beating.