Jump to content

Gas Block/Barrel problem


Recommended Posts

So, I'm neck deep into my 8th Front-End conversion on another Saiga 7.62x39mm rifle, and have encountered a new problem. I'll start by saying that I've spent the majority of the last week searching for similar problems with limited results, and no conclusive solutions. My hope is that you guys can help me solve this problem.

 

I'm attempting to pin my gas block in place, but noticed the gas tube is barely making contact with the gas block (less than 1/16th of an inch is being covered). It's just a little too short for me to be comfortable. I tried fitting at least 5 different gas tubes, and none of them yield more contact (gas tube lengths are surprisingly consistent!). My original gas block seemed fine, so I decided to check the differences between the stock Russian gas block and 4 different Bulgarian gas blocks. All Bulgarian gas blocks were identical, and the only difference between the Russian and Bulgarian gas block is the port hole diameter (Russian port is larger in diameter).

 

So, has anyone had to redrill new pin holes for their gas block? I've always used the stock pin cuts to line up my gas block on the barrel, but this one seems just slightly too far towards the muzzle. Here's the comparisons of the gas blocks...

 

null_zps77aef648.jpg

 

null_zps659e1a5c.jpg

 

null_zpscf1bedf6.jpg

 

I also noticed that the gas port hole doesn't line up with the hole in the barrel. It is partially "eclipsed" by the gas block itself! Here's some pictures of what I'm seeing...

 

Here's how the gas port lines up with the barrel (using the existing pin locations)...

null_zps4aa6c8bf.jpg

 

Here's what it looks like when the gas block is relocated rearward (see the shiny area in the barrel to the left of the gas block - this is how much the gas block is off)...

null_zps040d223b.jpg

 

This shows the gas block moved back to line up the gas port in the block with the barrel. If I redrilled the pin holes, they would overlap the existing factory pin cuts from the factory, and would only strip out...

null_zps91d1e6f9.jpg

 

Here's a backlit view of the factory pin cuts, and if I relocated the gas block back to line up the gas port...

null_zps5af01354.jpg

 

So, I need some advice. I don't want to weld the barrel, or redrill the pin locations. I've always just used the factory locations. Why is this different? Has anyone encountered this before? How do I install the gas block?

Link to post
Share on other sites

haven't done enough to run into this problem.

 

my experience on gas tube length is different than yours: have had several AKM tubes that are longer than others, and an AK-74 tube that is slightly longer than the other, which was odd because typically AK-74 tubes are not hand-fit to the rifle - that was the point of having the tensioning spring on the tube.

 

you can enlarge the port in the gas block by drilling through the hole in the bottom. the size of the port in the gas block doesn't really matter - it's the size of the gas port in the barrel that sets the gas pressure.

 

personally I would see if I could get another gas tube to test with. you could also temporarily install the gas block and check the space between the block face and the rear sight block, then compare to a fully assembled rifle. if the two rifles check out with the same space between these components, I would just pin it as-is and then work on finding a proper sized gas tube.

 

the other option is to position the block where you need it to fit your gas tube, and then use slightly larger pins - 1/8" vs original 3mm. this will ensure that the block stays put, even if you partially drill into the original pin channels. I feel you though, that's not what I would prefer to do either - the original locations *should* work.

Link to post
Share on other sites

Thanks for the recommendation mancat! I've actually fit about 5 different gas tubes to the GB/RSB, and they're all short. I even tried the original gas tubes (the sporter, smooth gas tubes) and they all come up short.

 

I've done many barrel conversions (swapping the FSB and GB while installing the hand guard retainer) and never encountered this problem, so these are strange waters for me to be in. I'm curious if anyone else has run into this issue, and what seems to be the best solution. It seems like there should be a common fix for this, and I'm hesitant to cut into the barrel.

 

On a side note, if anyone has a longer-than-average gas tube, I'd like to pick one up! ;)

Edited by fretout
Link to post
Share on other sites

I'm wondering if maybe there was a mistake made at the factory. Can anyone give me a precise measurement of the distance between the front of the GB and the front of the FSB (please see pic below - my FSB is not pressed on yet, but you can see the area of the paint where it was test fitted). I typically use a digital caliper, but I'm away from home at the moment. Maybe I can measure my barrel on this particular rifle and determine if there was a mistake made by Ishmash, and determine what the variance of measurement is....

 

Here is the area I'd like some measurements of...

null_zps4df15661.jpg

 

I'll try to upload some of my own measurements later today.

 

Thanks again everyone!

Edited by fretout
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Chatbox

    Load More
    You don't have permission to chat.
×
×
  • Create New...