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Late Reply was at gun show...
As Promised... May be a long post.
Here is the top Rail Difference Between a Polish Blank (Left) and a Bent Flat (Right)
Polish Blank Rails are Punch Sheared And Wide. Missing Bolt Carrier Ramp Right Rail. Polish blank where the bolt carrier drops in is to long this causes the bolt to jump out when back and hammer pressures up on the bolt.
Flat Rails are CNC Machined to AKM Spec.
Mag Well is a bit forward and the receiver is about .040 long on a Polish Blank is on the Right. Bent Flat is on the left
Material....
Flat 4130 / Inner Rails 4130 High Carbon can harden with map gas and salt water mix. Welding the same metals = less chance of a splash out if spot welding. Very strong welds
Polish Blank 8620 Contains lower carbon and nickel content and requires chemical hardening. Achieve proper hardening and keep it ductile enough to prevent cracking is hard. Poor weld-ability as inner rails are 4130 requires preheat prior to spot or tig fillet to form a good strong weld of dissimilar metals.
X and Y stamping
Bent Flat Top!
Polish Blank Bottom!
Photo is really enough said.
Polish is crude and to deep = thin on edges, weak, and they crack! But yes it has the 2nd Y a Flat does not but not needed unless your a 07/02! Even then not much force on the 3rd axis any way just holds the auto sear!
Off to rest...
As Promised... May be a long post.
Here is the top Rail Difference Between a Polish Blank (Left) and a Bent Flat (Right)
Polish Blank Rails are Punch Sheared And Wide. Missing Bolt Carrier Ramp Right Rail. Polish blank where the bolt carrier drops in is to long this causes the bolt to jump out when back and hammer pressures up on the bolt.
Flat Rails are CNC Machined to AKM Spec.
Mag Well is a bit forward and the receiver is about .040 long on a Polish Blank is on the Right. Bent Flat is on the left
Material....
Flat 4130 / Inner Rails 4130 High Carbon can harden with map gas and salt water mix. Welding the same metals = less chance of a splash out if spot welding. Very strong welds
Polish Blank 8620 Contains lower carbon and nickel content and requires chemical hardening. Achieve proper hardening and keep it ductile enough to prevent cracking is hard. Poor weld-ability as inner rails are 4130 requires preheat prior to spot or tig fillet to form a good strong weld of dissimilar metals.
X and Y stamping
Bent Flat Top!
Polish Blank Bottom!
Photo is really enough said.
Polish is crude and to deep = thin on edges, weak, and they crack! But yes it has the 2nd Y a Flat does not but not needed unless your a 07/02! Even then not much force on the 3rd axis any way just holds the auto sear!
Off to rest...
