ASE Utra Rimfire Suppressor on R55 Benchmark

[Odd Job]

After I got my SIG522 I applied for authority to purchase a suppressor for it, and I was surprised to find that the Metropolitan police encouraged me to ask for as many suppressors as I have rifles, as it didn't affect the fee I pay (£26 to modify a UK firearms certificate). They call suppressors "sound moderators" here. I got those put on my ticket within two weeks flat, the delay for me wasn't the police but sourcing the suppressor and getting the flash-hider off the SIG.
Because the barrel thread on my SIG522 is 1/2 x 28, I decided to get my Thompson Center R55 benchmark threaded 1/2 x 28 also, so I can mix and match cans. The 1/2 x 20 thread is much more common around these parts and I could have bought a brand new Parker-Hale suppressor from dealers at the club, but I heard that 1/2 x 28 cans could be had, I just needed to search a little. I duly got the R55 threaded by a gunsmith called Mike Hough.
This is the 1/2 x 28 thread on my R55:



I managed to get hold of a suitable suppressor for that. It is an ASE Utra rimfire suppressor, made in Finland and imported to the UK by Jackson Rifles. It is an all-steel can. This is what it looks like as attached to my R55:



This suppressor is solid and has a quality feel to it. I don't profess to be knowledgable about suppressors, I am just going by the general "feel" of it and the finish and construction of it compared to other suppressors at the club.
This can has 18 angled baffles, you can see some of them here, on the supplied guide rod:



I got this can CT-scanned (sub-millimetre axial slices) and then I used some radiology visualisation software to create 3D reconstructions of the can so you can see how these baffles sit in the tube:



The CT metal artefact makes the holes appear opaque in some parts, but you should get the idea from the image above that these are stacked at a slant. If you take the baffles out to clean the can, it can be quite tricky getting them back in. If you don't have the guide rod, you are done for in my opinion.

So, what do I think of this can?

Well, I like it, even though I haven't tried genuine subsonic ammunition yet. It's that pesky rule about hollow point ammo, I can't have it unless I am hunting / killing vermin on private property. And it is proving difficult to source LRN subsonics.
Anyway, I don't have access to a chrony and I don't have specialist decibel/noise meters so all I can do is offer you some video recordings. I tried three types of ammunition today:

GECO LRN
RWS target Rifle
Lapua Midas M

I fired 5 shots each with the suppressor and 5 shots each without. This was on an outside 50 yard range which is partly contained by a cinder block wall behind the berm, and a partial wall separating this range from the 25 yard range (off camera on the right). The firing position has a concrete floor and a low galvanised metal roof. Probably the results would be better out on an open field.
Apologies about the picture jumping, but I was interested in the sound and I needed this camera near the muzzle, and it has picked up recoil wobble from the bench.

GECO LRN no suppressor:

http://www.youtube.com/watch?v=lMkkz5bg-yo

GECO LRN with suppressor:

http://www.youtube.com/watch?v=LAPOFm-2m_E

RWS Target Rifle no suppressor:

http://www.youtube.com/watch?v=VJvAEh_3eSo

RWS Target Rifle with suppressor:

http://www.youtube.com/watch?v=D0pyEQ5R-j0

Lapua Midas M no suppressor:

http://www.youtube.com/watch?v=kHicONYu40M

Lapua Midas M with suppressor:

http://www.youtube.com/watch?v=d1e2a0hmUew

For my uses at an outside range, I am happy to use that rifle with any of those three types of ammunition without ear muffs (obviously that also assumes the other guys are shooting suppressed). Today there were two of us on that range, the other guy had an air pistol. This can does what it needs to do already, in my opinion and that isn't even with the ideal ammunition.

In terms of groups, the GECO was rubbish in that rifle and I was rubbish over-all. It was an off day for me, so the next part of this mini-review might need to be updated/repeated.

 

[Odd Job]

Here are the targets (they are from a ten spot sheet, each spot 2" in diameter):



Part of the reason I did that was to gauge how much POI difference there would be when comparing suppressed vs no suppressor. I expected bad groups from the GECO but the other two lots are all shooter error. I will get it done again another time, I was all over the shop today
On other days I have worked out that the difference between two tight groups (suppressed vs unsuppressed) is almost an inch with RWS Target ammunition. I'll get hold of some Eley Tenex rounds for the next test, that could be interesting.

Lastly, I wanted to see if there woud be a big difference between a wet and dry suppressor. I shot another ten spot target, this time with 10 shot groups. These images have been photoshopped to get the spots closer together. The first five spots the suppressor was dry:



And the next five spots were shot with a thin film of barrel oil on the baffles:



I don't know if anything can be deduced from that (besides me having an off day).
In terms of accuracy, previous visits to the range with the ASE Utra on the R55 have shown that the groups are marginally tighter with the can than without, but today was the first wet vs dry test.

I'll have to get more shooting done and update this thread, and do the same tests for the SIG522 of course.

I'm very happy with this can. The only thing is cleaning can be tricky. I made a little hook from a plastic coated wire hanger so that the baffles can be extracted, because after heavy use they sometimes don't come out by gravity alone.
I'd like to get another suppressor now, it will need 1/2 x 28 threads, I want to get a different make so I can mix and match a little

 

[LiquidTension]

Can you get the Wolf Match ammo? It should stay subsonic out of your rifle. Very cool CT scans, BTW.

 

[Odd Job]

Thanks, I will ask about the Wolf ammo.

 

[Odd Job]

I just had a look at the specs for the three types of ammo I tried. According to manufacturers' websites their muzzle velocities are listed as:

GECO Rifle: 330m/s out of a 650mm barrel (1080f/s)
RWS target: 330m/s out of a 660mm barrel (1080f/s)
Midas M: 325m/s out of a 660mm barrel (1066f/s)

According to the Wolf website their match ammo has a muzzle velocity of 1050f/s (they don't specify barrel length). Not a big difference between that and the Midas M.
I am going to try to get some anyway, because I want to see how it groups in my rifle.

 

[LiquidTension]

I like the Wolf because it stays subsonic in rifles and pistols, groups well for the price, and cycles the actions on all my semi autos. Sound wise the closest load I've found is Eley Tenex, which is indistinguishable from the Wolf when mixed in a mag. It also costs about three times as much.

 

[Odd Job]

I agree, my rifle LOVES Eley Tenex, but my wallet does not!