Black Creek Labs AR180 based rifle SVR2 Siberian approved for Non restricted FRT

Snyuk said:
The forward pin on the upper/lower is retained by a detent ball I believe. I think it would be popped out with a punch and the two would separate without issue.
I didn’t try it at the time but I don’t think it would be any more difficult than any other AR type platform? It’s very similar to the R18.

If anything you’d find it more annoying removing the hand guard. It’s a tight fit too the upper, but might loosen up after a few goes.


The thing with the piston is it sits about an inch into the upper, but only has about 1/2” of stroke/play. There isn’t a way to remove it from the gas block with that amount of room. The R18, despite having significantly more stroke, has the same style design (for the record, as I type this I think it might actually be possible. Again, amateur here)
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I would definitely give in another try disassembling without removing the gas block just to double check. You might be able remove the gas cup then get the rod out? I dunno.

I just find it hard to believe they'd actually design it so that the gas block would need to come off. That said, the manual sure makes it seem that way.
 
Callsigncupid on Instagram who is either a smith, tester, or both at BCL Edit: and then some, I have been told Callsigncupid is the owner of BCL, calling their shots, as it is were and seems edit has to have the most knowledge of the Siberian has stated in a comment on there Snyuk is right, that as written in the manual, the gas block has to come off to remove the piston.

I wonder if TNA or MRA could come to the rescue here. An adjustable gas block with a removable top hood to allow piston removal, perhaps combined with a handguard with a port to access the hood/ adjustment device on the gas block an allow easy removal of the piston?
 
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Deckard said:
True North would be a good option, with its adjustment part. I've built many ARs. Gas blocks have to be spot on.
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yep, it's hard enough to keep them solid and sealed without having to remove them for servicing the piston. still haven't from anyone on this thread about gong the distance and stripping the barrel off just to clean the gas system. is it possible or does the barrel nut contact the piston rod/spring?
 
Needing to remove the gas block to clean the piston and then lock tight set screws seems like a downgrade from the original ar180 design. I don’t quite understand why the piston couldn’t be removed for cleaning without removing the gas block…. You can even do that on the SVT40 where the design of the piston originated and that was made in the 1930s. I’d love to hear why they made the choices they did.
 
Clvland said:
Needing to remove the gas block to clean the piston and then lock tight set screws seems like a downgrade from the original ar180 design. I don’t quite understand why the piston couldn’t be removed for cleaning without removing the gas block…. You can even do that on the SVT40 where the design of the piston originated and that was made in the 1930s. I’d love to hear why they made the choices they did.
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I would suspect it is a reaction to so many loose gas blocks helping to break WK pistons. Between the barrel dimples for the screws to sit in and them being thread-locked, the gas block should stay in alignment, and so will the piston, until the system needs to be cleaned. If the instructions are followed, the gas block and piston should stay aligned after every gas system cleaning. Realistically, it shouldn't need more cleaning the recommended amount for .223, but I think they have to go for a more conventional and accessible system for 7.62x39mm, since you need to clean corrosive ideally after each range session, if the Libs don't introduce a standalone bill to include the now dropped bill 20 amendments or OIC to ban the 180s before that version can be born.
 
Loctite doesn't cut it for gas block screws. There just isn't enough heat resistance to ensure it won't come loose. Staking the screws or Rocksett was an easy fix for other 180's but its concerning if the gas block needs to be removed for disassembly.
 
Here is the official gas block cleaning instructions from the manual, on page 15, https://www.blackcreeklabs.com/bclPub/uploads/2023/01/SRV2-Siberian-User-Manual-REV-A.pdf :

Black Creek Labs SRV2 Siberian Manual said:
4.7 GAS SYSTEM CLEANING
It is recommended to clean the SRV2 gas system approximately every 1,500 rounds
to maintain maximum efficiency and reliability of the firearm.

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1. Remove the handguard. Use a 9/64” Allen Key to remove the handguard
screws. Once the screws are removed, the handguard can slide off the
barrel nut. The re-installation torque for the handguard screws is no more
than 20in-lb.

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2. Remove the gas block set screws using a 3/32” Allen Key. Once the screws
are removed, remove the gas block, piston, and piston rod from the
assembly. Apply medium strength threadlocker (blue) to the gas block set
screws when re-installing and tighten firmly.
Use a carbon removing solvent and thoroughly clean the piston (1) and the
gas block (2). Also ensure the barrel is cleaned and any carbon is removed
from the gas port and gas block journal.
Click to expand...
 
That Gas system design flaw does it for me I'm no longer interested, until such time as the system is redesigned to allow Piston removal independant of the Gas Block.
 
I think I figured out the other reason they made the piston only removable with the gas block removed. There is a narrowed portion of the main part of the piston that enter the receiver is tiny compared to any other 180 design, and there is no spring along that portion. Having a longer narrow portion on traditional 180 designs allows you to compress the spring along it with your hand to remove the piston, but having that narrow portion outside the receiver introduces an inherent weakness. The SRV2's design in theory reduces that weakness, since the thinned portion is much smaller, but at the trade-off you have to remove the gas block to remove the piston.
 
Okay, the gas system (dis)assembly have ruined it for me. Already waiting for a gen2

Why can't they just do a simple 3-piece gas piston/oprod combo like the AR-18/SVT-40/Gewehr 43? After removing the BCG, you hold one piece of the rod or piston cup in front while shoving the rest into the receiver while compressing the gas piston return spring, and the 3-piece rod pops right off. No need to mess around with the gas block. It's not rocket science.


A quick history lesson:

SVT-40, a rifle designed 84 years ago: The piston return spring guide rod itself connects to the oprod (the longest one) via a cup. The extra width of the cup provides an edge for the spring to sit on. The guide rod itself is the same diameter as the oprod, therefore no change in stress.
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AR-18: Slightly simplified the Tokarev system by making the spring guide rod and oprod a single piece, but added an extra collar to locate the oprod return spring. Therefore the hole in the receiver is large enough to accomodate the user pushing the oprod backwards to pop the piston cylinder/oprod connection, then remove the oprod and piston like you do in a SVT-40.

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Remember how the WK180C tried to incorporate the oprod and the piston return spring guiderod into one by thinning out the receiver end of the oprod? It seems like they've done it again on the BCL SRV2.

WK180C: The oprod narrows to accomodate the spring. The stress concentration in the sudden contour profile change made it much more likely to snap off, like here: https://www.reddit.com/r/canadaguns/comments/fn8et3/wk180_broken_piston_again_ridiculous/
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And finally the BCL SRV2, thanks to Synuk for the images:
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The narrowing is still there, which means the opening on the receiver is too small for you to feed the oprod into the empty receiver (because you have already removed the BCG by this point of the disassembly process) and remove the oprod/piston.
You can see that in the manual as well:
image.png

After reading the entire manual, it seems like BCL did not have an oprod return spring. They expected the BCG to slam the spring back home when it chambers a new round. Therefore they thinned out the rear end of the oprod to prevent rearward overtravel and the rod falling into the receiver. The rest of the world have a similar solution for this brand new issue they've created: It's called a piston return spring. Or, they could simply engineer the gas block in a way that you can remove the piston from the front.


So yeah, people never learn from others' mistakes. The irony was that, the AR-18 was envisioned as a simpler rifle for countries with less manufacturing capabilities becasue you are less likely to mess up a simple oprod...
 
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that all makes sense - they removed the spring to avoid the weak spot in the 180 system, but without the spring holding it together you have to design the system to not come apart (without removing the gas block). the solution is the ar180 design which has the external lip on the piston to hold the spring, but then presume you need a larger handguard (ar180 didn't have to deal with folks wanting a rail the entire length of the handguard). rwa did a pretty good job of fitting a three-piece piston and spring on their receivers but had to lower where the piston passed through the upper to fit it all in - it interfered with the barrel nut so they used a mounting plate to hold the barrel on instead. not sure how say the r18 gets it done.
 
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If you need to have us remove the gas block to clean it they could have at least looked at copying the sig/Famae 540 series gas block. You can remove it quickly with just a cartridge. No lock tight needed.
 
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