For new builders, this is the sequence only and not detailed build instructions...the "how to" part is addressed in the build tutorial on the home page.
This sequence is prepared so you are ensured of not having to do things twice and, if followed, you will end up with a pretty good shooter.
Before building, study the disassembly tutorial on the home page to become familiar with the parts and their names.
If you use screws in lieu of rivets you then have to do the compliance welds as shown in the build tutorial on the home page. You do not need the welds if using rivets.
Caution: Don't get overwhelmed and try to understand the whole thing at once. If you take the checklist one step at a time with the parts in front of you it will unfold easily. For those genius' with good memories you can disregard this caution.
If you have an ORF or Brass Cartridge rsp some of these steps can be skipped.
1919A4 Semi Build Sequence
1. No serial number is required for a home built semi 1919 nor is it required to be registered, but if the rsp is engraved, stamp serial number and inspectors initials in the spaces provided in the engraving. You can use any serial number you wish; i.e. birthday, Pearl Harbor Day, etc. I use my initials for the inspectors space. On the inside of the rsp under the top cover I typically stamp my name and date. Some folks do it where the bolt retracts, but I do it under the top cover so if we ever have to grandfather our guns the date is in a place not easily construed as being added later...it would be very difficult to add later in this location.
On my personal builds where the sideplate is not engraved, I stamp my serial number on the bottom of the trunion and I prefix the number with the letters "S/N" so it cannot be construed or confused with a part number for the trunion. You may stamp your serial number at any location if you choose to have one. A serial number is a good idea in case the gun is stolen or, heaven forbid, we have to one day register them.
2. Remove old rivet from right rear cartridge stop…saw it off and punch it out.
3. Place the right rear cartridge stop in it's proper location and using the stop as a guide, drill the hole...this typically is a 13/64" drill bit and not 3/16".
Do not center punch the hole and drill it without using the stop as a drill guide/jig. Install right rear cartridge stop onto semi rsp. Look in your rivet set and you will find one odd rivet that fits the cart stop. Rivet can be domed on the outside or hole can be chamfered and rivet flattened and ground smooth…your choice. You don't have to worry about the rivet head sticking up a tad on the inside, it won't interfere with anything.
4. Install pintle pad to semi rsp by drilling the 12 o’clock and 8 o’clock rivet holes and countersink on the backside of the rsp. Smash these rivets flat…they will be ground smooth later. (Do steps 5 thru 14 first if no 9/16” pintle hole or 4 o’clock rivet hole is pre-drilled in your semi rsp.)
PINTLE PAD MUST BE INSTALLED PRIOR TO SEMI RSP INSTALLATION ONTO THE TRUNION.
5. Assemble entire receiver including barrel shroud…no booster.
(MAKE SURE SEMI RSP SEATS SQUARELY IN BOTTOM PLATE SLOT, IT SHOULD RESEMBLE THE FIT OF THE LSP INTO THE BOTTOM PLATE. IF IT DOESN'T FIT SQUARE THEN GRIND THE SHARP EDGE OFF THE RSP UNTIL IT SEATS SQUARELY).
6. Insert top cover bolt to aid in alignment.
7. Using a straight edge, align the barrel shroud and check the trunion location to ensure feed tray is level with semi rsp link ejection port.
8. Clamp the receiver tightly.
9. From the left side, drill the 4 o’clock pintle pad hole (viewed from rsp) using the trunion as a guide.
10. From the left side, using the existing large trunion pintle hole and a 9/16” drill bit, center mark the large pintle hole on the inside of the rsp (unless already pre-drilled by your rsp mfgr).
11. Using the special transfer punch, locate and center-punch the 30-06 front right cartridge stop hole…if you want it. If you don't have the special transfer punch then put your 30-06 front stop in your 308 stop and install the 308 stop as far as you can and then mark the '06 rivet location on the inside of the rsp with a Sharpie or spray paint. Some builders wet the end of the '06 stop rivet with paint and quickly install it to make a paint print.
12. Disassemble the receiver and drill the 9/16” pintle hole in the semi rsp (if not pre-drilled).
13. Drill the 30-06 right front cartridge stop hole in the semi rsp (if used).
14. Chamfer the 30-06 right front cart stop hole on the outside.
15.
DO STEP 4 AT THIS TIME IF NOT ALREADY DONE.
16. Reassemble receiver, align barrel shroud, check trunion location and clamp tightly.
17. Using the bottom plate as a guide, drill all the bottom plate rivet holes.
Do not try to center punch these holes and then disassemble it and drill them on a drill press...the bit can walk and the holes will then be off...use the bottom plate as a drill guide/jig. (DO NOT DRILL THE TWO LARGE TRUNION RIVET HOLES AT THIS TIME).
18. From the left side, using the existing lsp holes as a guide, drill the two top plate holes all the way thru the semi rsp. The long rivet that goes in the front hole may be 13/64" in lieu of 3/16" so check the size before you drill. Also, in some rivet sets and on some guns the two rear rivets are also 13/64" in lieu of 3/16"...you should find two domed rivets in your set so check the size before drilling. The two rear domed rivets are installed from the inside out and the head will have to be ground off on one side in order to fit under the top plate lip on the inside. Some rivet sets, like Black Bear, already have the head ground off on one side for you.
19. Disassemble the receiver…leave barrel shroud on trunion.
20. Countersink all of the bottom plate rivet holes on the inside of the semi rsp. Rivet heads must be slightly below surface of the plate.
21.
LAST CHANCE TO DO STEP 4 OR BREAK OUT THE WELDING MACHINE LATER!!!
22. Reassemble the receiver, align shroud, check trunion location and clamp tightly.
THIS IS THE LAST CHANCE YOU HAVE FOR A SQUARE RECEIVER SO CHECK ALIGNMENT THOROUGHLY.
23. Slide your internals in and check function. Don't forget to temporarily install your breach block cam into the bottom plate or the bolt won't lock up...the big notch goes towards the front.
24. Remove the breach block cam and insert the rivet bucking bars and set all of the bottom plate rivets.
25. Insert and set the three top plate rivets…the long one goes in the front hole. (To fit below the top plate lip on the inside, the two rear rivets will need the head ground off on one side and are then inserted from the inside out.)
26. Set the long 4 o’clock pintle pad rivet…smash flat on both sides and grind smooth.
27. From the left side, drill the two 11/32” trunion rivet holes.
28. Using a 1/2” drill bit, chamfer the two trunion rivet holes in the semi rsp.
SOME RIVET SETS HAVE 11/32" RIVETS THAT ARE MARGINAL IN LENGTH SO IF THE CHAMFER IS TOO DEEP THERE WON'T BE ENOUGH RIVET TO SMASH COMPLETELY OUT AND FILL THE CHAMFER SO THERE WILL BE A VOID AROUND THE RIVET HEAD. A 1/2" CHAMFER WITH A DEPTH OF APPROXIMATELY 1/4 TO 1/3 THE THICKNESS OF THE PLATE USUALLY PRODUCES A NICE RIVET, BUT CHECK YOUR RIVET LENGTH BEFORE MAKING THAT DETERMINATION.
29. Insert and set the two large trunion rivets. Pound the snot out of them!!!
30. Using the special bucking rod, install the 30-06 front right cartridge stop (if used). If you don't have a special bucking rod then fill your 308 front stop one third full of flat washers and then insert your 30-06 front stop and install the whole assembly onto the lsp. Then lay the gun on it's left side with the 308 stop resting on the anvil and using the 308 stop as the bucking block, pound the rivet head. This rivet head must be smashed into the chamfer and then ground flat. Do not dome this rivet on the outside or it will interfere with the top cover cams...chamfer the hole and smash flat.
31. Grind and dress all smashed rivets, edges, mating surfaces, etc.
32. Bead blast and parkerize. NOTE: You only need to bead blast parts that are visible on the assembled gun…bare spots on internal parts will parkerize and areas already parkerized on internal parts will retain their finish.
33. Install the breech block cam and tighten the screw and then back off 1/4 to 3/8 turn and stake in place from the inside. This cam is to be loose to allow expansion due to heat build up in the gun. If it is tightened up the breech block may not fully engage the cam and lock up the bolt properly when the gun gets hot. According to FM 23-45 (pg 18, first para, last sentence) the 1919 is designed to drop the firing pin 1/16" before lockup, but after the breech block is engaged in the cam. If the cam is too tight and the breech block is not seated in the cam before the firing pin drops at that 1/16" milestone then out of battery ignition can occur.
34. Assemble gun for headspacing and test cycling. You may leave the backplate off and by pushing forward on the charging handle you can test function the internals and the trigger pull. View thru the rear to check trigger and sear engagement. Make sure your trigger return spring is in place and that the retaining screw is not so far in that it hampers trigger travel or not so far out that it hits the backplate and prevents it from sliding down the slots and seating...if the screw is too far out it will snag on the round buffer plate when you try to slide the backplate down.
35. Don't read this more than twice or your brain will hurt
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