My first new barrel installation

[turbosc20]

So I ordered some of these cut barrel kits from Apex a month or 2 ago. I also purchased 2 pistol barrels as well. Yesterday I got around to pressing, headspacing the barrel pin.

Surprisingly it wasn't has hard as I thought. Here is the end result.

Next step is to remove the sight block pin from the old barrel... Fun.

 

[blackshirts1]

hi turbo....I am getting ready to build my first AK's. PMKMS underfolders from Apex with their new US Barrels.

I have read and watched most everything that can be found on the net but I'm still a little unsure of installing the new barrels and headspacing. I have the tools needed I believe including the go/no go guages.

From what i have seen on final headspacing it needs to be done with the receiver assembled, and that looks pretty straight forward........but you are the first one that i have seen to post anything about the initial (other than the guy that posted about a yugo build elsewhere) new barrel installation and headspacing.

can you email me instructions on how you did this step? or post some pictures and instructions?

 

[turbosc20]

hi turbo....I am getting ready to build my first AK's. PMKMS underfolders from Apex with their new US Barrels.

I have read and watched most everything that can be found on the net but I'm still a little unsure of installing the new barrels and headspacing. I have the tools needed I believe including the go/no go guages.

From what i have seen on final headspacing it needs to be done with the receiver assembled, and that looks pretty straight forward........but you are the first one that i have seen to post anything about the initial (other than the guy that posted about a yugo build elsewhere) new barrel installation and headspacing.

can you email me instructions on how you did this step? or post some pictures and instructions?

You're probably talking about this one?

http://www.gunco.net/forums/f43/new-m70-barrel-install-tutorial-28039/

I like to get my ak front end to a status of a barreled kit (with trunnion attached). Easier to work with and prevents damage to the receiver.

Your handguard retainer and extractor cutout should be done already on the barrel you bought. I recommend using your handguard retainer to line up with the front trunnion and press in the barrel that way first.

There's a little tab inside the trunnion where it looks like where the barrel would stop but leave a 1mm gap. Insert your no-go gauge into your bolt (with carrier) and insert it into the chamber. If the bolt/carrier locks into the chamber, the barrel needs to be pressed in more.(I'd use a brass hammer to knock the barrel in alittle more.)If it doesn't go in, use your Go gauge to see if your bolt locks in. If your go gauge doesn't lock in, then you need to hit the barrel out alittle.

Once the headspace is satisfactory, use a drill press with vise (keeping it flat as possible) and drill the barrel pin hole on the trunnion with a 7mm drill bit. I also used a 7mm reamer after drilling. It made it look really smooth. Then press in the barrel pin.

Now you're ready for your sight block, gas block and front sight. I believe those are 4mm (rear sight block) and 3mm drill bits. I haven't got to this point yet. I hope your kit has it's barrel accessories removed already because those pins are a bitch to remove from the barrel... ugh.

 

[blackshirts1]

Thank you very very much. Your method makes sense and is simple and straight forward. Once again, thank you very much!

I spent a few hours last reading a blog where the gentleman installs the sight block first....obviously that works well for him, but your method makes sense to me, especially where i had been reading about headspacing prior to the receiver installation. But nobody explained what one was to do in regards to checking the headspace at this point (prior to riveting the receiver to the front trunnion).....your info clears things up nicely!

I appreciate you giving the size of drill bits and reamer to use also, that helps a bunch.

One more question that arises from other reading......(apparently you had no problem using a regular drill bit to go through the barrel)........somewhere a builder stated that is was best to use a "mill bit" (not sure that is what he called it or not) as it is a flat ended cutting bit that would be easier on the rounded edge of the new barrel.

Do you feel that it would be worth purchasing the mill type bit? or did the regular bit work easily enough for you that it would be a waste of money to use the mill type bit?

My kits do have the pins removed already, so that should simplify things from what you've stated.

Now, my final question for this round........from what i've read from builders using kits with a complete original barrel......it appears the normal method has been to demill the cut receiver from the trunion. Then press out the barrel pin and remove the barrel from the trunion so that one can totally remove old rivets from the trunion. At this point it appears that they were then riveting the front trunion to the receiver and finally they would press the original barrel back in. Since it was the original barrel and trunion the headspacing was most likely correct.

It appears to me that most of the lesser expensive kits are likely to have non-matching numbers now days, i will have to look, but hopefully the bolt carrier/bolt and front trunnion at least match, but lets say they don't. (I'm just pointing this out in case you have any advice in that area)

Anyway, my question to you is in regards to riveting the front trunion to the receiver.....from my reading I have been under the impression that one needs to rivet the receiver to the front trunion before final pressing of the barrel into the trunion and installation of the barrel pin.

From what you have said it appears that things worked fine for you to go ahead and pin the barrel to the trunion before riveting the trunion to the receiver. Can you explain how riveting the barrel assembly to the receiver was done? (from what i have seen one has to have the rivet jig inside of the trunion in order to set the two rivets that sit flush or lower in the area that the barrel is pressed into.) I am assuming you are pressing the barrel pin to make the complete barrel assembly to insure correct headspace, then you remove the barrel pin and barrel to allow riveting of the trunion to the receiver, then final pressing and pinning of the barrel?

forgive me for the long post but i would like to get this done correctly the first time if at all possible!!

 

[turbosc20]

Thank you very very much. Your method makes sense and is simple and straight forward. Once again, thank you very much!

I spent a few hours last reading a blog where the gentleman installs the sight block first....obviously that works well for him, but your method makes sense to me, especially where i had been reading about headspacing prior to the receiver installation. But nobody explained what one was to do in regards to checking the headspace at this point (prior to riveting the receiver to the front trunnion).....your info clears things up nicely!

I appreciate you giving the size of drill bits and reamer to use also, that helps a bunch.

One more question that arises from other reading......(apparently you had no problem using a regular drill bit to go through the barrel)........somewhere a builder stated that is was best to use a "mill bit" (not sure that is what he called it or not) as it is a flat ended cutting bit that would be easier on the rounded edge of the new barrel.

Do you feel that it would be worth purchasing the mill type bit? or did the regular bit work easily enough for you that it would be a waste of money to use the mill type bit?

I used the one that I bought from ak-builder. I think it's a mill bit?

http://ak-builder.com/index.php?dispatch=products.view&product_id=30048

My kits do have the pins removed already, so that should simplify things from what you've stated.

Now, my final question for this round........from what i've read from builders using kits with a complete original barrel......it appears the normal method has been to demill the cut receiver from the trunion. Then press out the barrel pin and remove the barrel from the trunion so that one can totally remove old rivets from the trunion. At this point it appears that they were then riveting the front trunion to the receiver and finally they would press the original barrel back in. Since it was the original barrel and trunion the headspacing was most likely correct.

Sounds right to me. I'd still check the headspace again once you press the barrel back in just to be on the safe side.

It appears to me that most of the lesser expensive kits are likely to have non-matching numbers now days, i will have to look, but hopefully the bolt carrier/bolt and front trunnion at least match, but lets say they don't. (I'm just pointing this out in case you have any advice in that area)

Since you're using a new barrel and adjusting the headspacing using that bolt, you should be good to go.

Anyway, my question to you is in regards to riveting the front trunion to the receiver.....from my reading I have been under the impression that one needs to rivet the receiver to the front trunion before final pressing of the barrel into the trunion and installation of the barrel pin.

From what you have said it appears that things worked fine for you to go ahead and pin the barrel to the trunion before riveting the trunion to the receiver. Can you explain how riveting the barrel assembly to the receiver was done? (from what i have seen one has to have the rivet jig inside of the trunion in order to set the two rivets that sit flush or lower in the area that the barrel is pressed into.) I am assuming you are pressing the barrel pin to make the complete barrel assembly to insure correct headspace, then you remove the barrel pin and barrel to allow riveting of the trunion to the receiver, then final pressing and pinning of the barrel?

You assumed correctly. I'm going to remove the barrel pin and press it back out when i'm ready to rivet the trunnion onto the receiver. I just wanted to install the barrel to the trunnion, headspace it and get everything else lined up and installed. Just seems easier to work with when almost half the rifle is out of the way.

forgive me for the long post but i would like to get this done correctly the first time if at all possible!!

No problem

 

[blackshirts1]

Awesome.....you did a great job of making the new barrel installation a simple enough process!!!!

Once again, thank you very much!

Craig