Follow Up - New Silencer Day - TBAC Spiro
I mounted the Spiro-hub up to my 6 ARC Seekins build and took it out to group some hand loads today. Here's my non-scientific and non-professional thoughts.
Rifle Details:
-Receivers: Seekins Precision (IMRT Upper with 15" handguard)
-Trigger: Geissele SD-E
-Pins & Detents: FCD
-Barrel: Proof 18" Stainless Steel
-Muzzle Device: TBAC Compact Brake (CB)
-BCG/Bolt: JP Enterprises FMOS Type 2
-Buffer: JP Enterprises Silent Capture System
-Stock: B5 Systems Precision Stock
-Bipod: Atlas
-Scope Mount: Nightforce
-Scope: Nightforce ATACR 4-16
POI vs. POA:
There was little to no POI shift. I forgot to check my windage and had .3 mil R dialed on so the impacts were right of my POA. Elevation wise, it was right there (see Pic 1).
Sound Signature:
It's a relatively short silencer on an 18" barrel. It's still loud but not horrible. I removed one ear plug and fired a single shot. It was loud but nothing like shooting unsuppressed.
Grouping:
I was load testing today while shooting the Spiro and had a few groups right around .5 MOA at 100yds. In both cases I dialed .3 mil up to preserve the POA. Two of those groups are attached. One group was shot with the Hornady 105gr HPBT and the other with the Sierra 107 SMK HPBT. Load details below:
Hornady 105 (5 shot .538 MOA)
-Hornady once fired brass
-Federal GM205AR primer
-CFE 223 @ 27.5gr
--ES: 19.4
--SD: 6.4
--Avg. FPS: 2469.5
Sierra 107 (5 shot .523 MOA)
-Hornady once fired brass
-Federal GM205AR primer
-CFE 223 @ 27.5gr
--ES: 22.4
--SD: 8.3
--Avg. FPS: 2376.9
Comparison:
Prior to the Spiro I was using an OCL Polonium on this rifle. The OCL is a high back pressure silencer and as a result I had to tweak the buffer weight and gas system dramatically to get the rifle to cycle suppressed and unsuppressed. The rifle has a Superlative Arms AGB and was set to the bleed off position. In order to get the rifle to cycle with the Spiro I had to put 8 full turns into the AGB. I'll redo the buffer weight and spring as well for further testing and see if I can't get it shooting a bit softer now that there is less back pressure.
The OCL is a decent silencer but being a high back pressure silencer there was a lot of gas directed back towards the shooter. The Spiro doesn't have this issue and the rifle was actually pleasant to shoot.
Conclusion:
Overall I'm happy with the silencer. It is what I hoped for from TBAC in regards to accuracy and POA/POI shift (minimal). Granted my TBAC experience before the Spiro was only the Magnus S RR SR on my 6 ARC bolt gun. However, I am happy with the overall performance.