Guy Montag — Nicoroshi

chamber of the barrel.(Or even better, use a combination of all of the above to ensure the chamber is as absolutely as clean as possible before continuing.)

STEP 5. Align, and press front trunnion onto chamber end of barrelThis next step is where we will use the 12 Ton hydraulic shop press to mate the front trunnion and rear-most barrel journal. (NOTE - Toth Tool sells a barrel pressing tool that does not require a press. He also sells a tool to crush rivets without a press, See Appendix II)

The 'Harbor Freight' model is what most builders have determined is the best value for the dollar and well suited to this job. The 20 ton model can generate too much pressure rather quickly, and while it can be used it requires more skill and care so as not to over force a bad fit or even bend a barrel. People have also tried using arbor presses but it is generally accepted that these do not have enough power to do the job required.

IMPORTANT: Be sure you have read the manual and safety info for your shop press. Also be sure that it is both stable and secure on a flat floor surface before attempting any pressing. Only solid cast iron or steel pressing plates should be used to support the work pieces.

Important note on metal lubrication:If it squeaks, you oil it. But if you want it to slide you grease it.

A moderate coating of white lithium or Moly grease is recommended on all journals to help them to slide, without galling, when pressing any parts together.

Use the lower handguard retainer top, which is flat, to align the front trunnion on the barrel. The top of the front trunnion is also flat.

Sight from the chamber end, and rotate the front trunnion until the top is parallel with the top of the lower hand guard retainer. Now ensure your extractor cut on the chamber end of the barrel is aligned at the 11 o'clock, and 4 o'clock position.

Set the rear of the trunnion on a hard surface, and use the rubber mallet to set the barrel into the front trunnion (just start it going in by hitting on the muzzle end).

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BUILD YOUR OWN AK : VOLUME I

Check the barrel/trunnion assembly for proper alignment; ensure barrel is entering the front trunnion straight. This can be done by looking at the barrel/ trunnion assembly from the side, and top.

Tap on the connection with the rubber mallet until it's straight to the eye.(i.e. -the barrel looks to be entering the trunnion straight)

IMPORTANT – Before pressing, verify your barrel alignment from the chamber end and verify your extractor cuts are oriented in the correct location. See image above of a 5.45 barrel.

Set up the hydraulic press by placing the press work support bar high enough to clear the barrel assembly, and buffer on muzzle. NOTE - On the Harbor Freight 12 ton press the bottom pins should be in the third hole up from the bottom for a 16” barrel, but this dimension will vary depending on barrel length. Now set the front trunnion down on the

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Guy Montag — Nicoroshi

lower pressing block with barrel vertical, and align the ram of the press with the muzzle end of the barrel.

Ready to press in barrel

Always buffer the muzzle end of the barrel with soft metal (pennies, an aluminum disk or something similar).

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BUILD YOUR OWN AK : VOLUME I

Hold from the trunnion, and press the barrel into the front trunnion. The reason we hold the trunnion, and not the barrel to ensure the bottom of the trunnion is sitting flat to the block. If holding the barrel the trunnion may be cock-eyed causing the barrel to be pressed in out of line, and galling the barrel journal in the process.

When using the press, begin by pumping the press handle slowly while watching the connection where the barrel is entering the front trunnion. You should be able to see the barrel sliding into the trunnion as you continue to pump. Do not go all the way to the bottom of the stroke with the handle. This will cause the press to bounce, and could potentially move the alignment you've set up. Take your time, no rushing this step.

Watch carefully for any flexing of the barrel or not being aligned straight and vertical. If it is flexing or not moving straight down—Stop. Remove any pressure from the press ram, adjust your setup as needed to ensure a straight press on the barrel before continuing.

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Guy Montag — Nicoroshi

Press barrel in until trunnion journal is sticking out of the front of the trunnion about 1/8".

(NOTE – this distance is not absolute, and will vary depending on maker of barrel. Some stick out about 1/8” and some sit flush to end of barrel journal when head space is correct)

Now remove assembly from press, and check the headspace.

Again, inspect and ensure the chamber is completely spotless/clean and without any foreign materials, chips, dust, patch fragments etc. that could hamper an accurate measurement before continuing !

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BUILD YOUR OWN AK : VOLUME I

HeadspacingWe will be using a perfect, undamaged, new live round as a GO gauge. Place it fully into the chamber and then position the stripped bolt into the locking grooves on the front trunnion. Close the bolt slowly by turning it clockwise (when viewed from the rear) and see where the bolt stops.(without any forcing on your part). Then repeat this with a NO-GO gauge in place of the live round.

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