Introduction

PBS-4 next to PBS-1 is one of the most acknowledged AK family silencer. In contradiction to PBS-1, dedicated for 7.62x39mm cartridge, PBS-4 goes with AKS-74U. This idea lead to specific construction of the muzzle, to generate proper pressure able to move breech automatically after taking a shot. Normally this is supported by specific part called bugle or rumcajs). This characteristic of PBS-4 makes it impossible to use with long barrel AK using 5.45mm cartridge.

 

This silencer became famous mostly thanks to combo including:

<ul> <li>PBS-4 silencer itself;</li> <li>grenade launcher GSN-19 (modified version of BS-1 "Silence");</li> <li>sub-carbine AKS-74UB (ready to install grenade launcher and as well endued with proper leaf sight);</li> </ul>

It was known as Бесшумный Стрелково-гранатометный комплекс "Канарейка ( Besshumnii strelkovo-granatometnii compleks "Kanareika" ). Such a set, was probably never really more than an experiment. One of the reasons to that was bad ballistic specification of sub-carbine in such a configuration. AKS-74U is rather famous for being inaccurate therefore using subsonic cartridge (to extend durability and silencer effectiveness) could not help at all. Proverbial nail in its coffin was 9x39mm cartridge (SP-5, SP-6) which was was (as subsonic cartridge, meant to be used with silenced weapon) way above any 5.45mm could ever reach. Best known carbines using this round are VSS "Vintorez" (Винтовка Снайперская Специальная "Винторез" - Vintovka Snaiperskaya Special'naya "Vintorez") and AS "Val" (Автомат Специальный «Вал» - Avtomat Special'nii "Val"), but number of guns using this round is really big considering the short time of its output.

Exterior and construction

 

Fortunately construction of real PBS-4 is well backed with photos, so in theory - to make a replica should be no problem. The silencer by Silesia Factory is supposed to be patterned on one by VFC. Unfortunately I have not seen VFC product so I cannot make any comparison, I can only say - SF makes really good impression. Weight standing at about 400g (0.88 lbs) makes it pretty heavy, but not as heavy to be worried about rifling of our barrel. Speaking of a rifling: tested piece has 24mm rifling suitable to VFC and DBoyi products, but final product would be sold with 14mm adapter (CYMA, TM, JG and so on).

Silencer casing is divided into two main parts - short (5cm or so) screwed on a muzzle rifling and longer part which is an actual silencer (or rather its case). Both parts are connected by rifling. To avoid dropping a silencer during usage it has a latch, attached to silencer by two screws. Latch is a small metal plate in the "L"-shape, which clinches into cavity all over the girth right next to the rifling which keeps together both parts of silencer. Even though solution is simple, seems to be pretty solid (silencer will surely not unscrew itself) and against all the odds - convenient . To unscrew the silencer you have to unscrew a bit one of the blocking screws (closer to the bottom of "L"-shape) and bow it up. If the screw would be loose enough, we may dismantle silencer. It is easy to scratch a paint while unscrewing. It is said to be typical for Silesia Factory, due to production process ( details unknown ).

After dismantling a casing we may take out actual silencer, which is additional inner barrel with a bigger diameter (it would easily take in AEG inner barrel) with bored vent holes. Such a barrel has attached rings made of something like a spongy rubber, which divides the chambers. It is quite innovative solution ( I haven't seen this solution in other products) but if it is effective? I shall prove it soon.

When mounting tested silencer on VFC AKS-74UN (same for Boyi) it came out that it is impossible to screw up the rifling - due to too long silencer inner barrel. To make it possible to screw it up, I had to shorten inner barrel by about 1cm (0.39 in), which I did by regular metal file. I hope final product would not have this failure. 

Last thing I want to say about the look is really tasty - marking. Next to the rifling there is engraved ( let me point this out - engraved - not printed ) star ( which is a Russian Tule factory marking, previously producing inter alia AKS-74U) and serial number. Unfortunately serial number is exactly the same for every SF PBS-4, but it should be nothing difficult for engraving device.

Suppression

Silencers suppress only noise coming out through a barrel - so sometimes it is difficult for a shooter do determine how well is a silencer working. Nevertheless after mounting it on VFC AKS-74UN (not yet modified for inner barrel problem) I could state shooting noise was visibly lowered. "Tone" difference is noticeable - it is more bass, and therefore more difficult to locate on game area (as far as I am concerned). Suppression level cannot match i.e. TM P90 with silencer though suppression is perceptible.

 

Summary

 

General impression is good. It suppress and looks good. Though after mounting PBS-4 on AKS-74U it is comparable to regular AK-74 - so it looses its compact size. You can always unscrew the silencer anytime you want, unlike outer barrel of full size AK-74.