Loads that cycle a 10.5" upper
 

I see quite a few members here that either have a .300 Whisper SBR AR15 or have one on the way. I just received my 10.5" M1S custom barrel yesterday.It has a .082" gasport @ the pistol position.So far, the only subsonic loads I have been able to find here for this configuration are;

Noveske 10.5",.0875 port, 12.3 gr.AA2015 w/220gr. SMK

10.5" barrel, .110 port 8.5gr.AA#9 w/220gr. SMK

Noveske 10.5",9.2gr.H110 w/220gr. SMK.

I assume most would only be interested in loads that will cycle an AR15 action. I will open the port if necessary, but will try the loads above first.
Feel free to dump your AR15 SBR .300 Whisper loads here for all to disseminate. Don't forget to add barrel length & gas port dia. if possible.

Noveske 10.5", pistol gas system. gas port opened up to 0.100"

10grs of H4227 behind SMK 220grs

1096 fps
1081
1102
1087
1090

I'm going to reduce the charge slightly to get it around 1050 - 1070.

9.2gr of H110/220smk doesn't cycle in my 10.5" shillen/tp555 barrel with a .083" gas port. It will sometimes pick up the next round. I'll have to try AA#9.

Jon

Well, I tried 8.5gr. AA#9 with 220gr.SMK's & CCI 450 primers.
1008
1069
1020
This load failed to cycle. Tried again with 8.8gr. of AA#9
1071
1087
1070
This load also failed to cycle. For reference, the load that cycled my 16" barrel,8.5 gr. Alliant 2400, 220gr.SMK's, also failed to cycle in the 10.5"bbl.
After scouring this site for info,it seems as though my port may be a bit narrow. The main reason for keeping the gas port as narrow as possible is so that I can use supersonic ammo without hammering brass & rifle components.To achieve this, a lighter buffer,carrier,or less spring pressure may all need to be considered.Soon, the Noveske Switchblock may be available and allow widening of the port for subsonic ammo.

Opened up the gas port to .086, #44 bit.
8.5 gr AA#9 w/220gr.SMK cycled all 20 rds.from a full 20 rd mag. Velocities;
1018
1031
1007
964
955
981
991
958
967
974
981
I will play with this for a while. This Model 1 sales barrel requires that I seat to 2.170" c.o.a.l.

Model 1 Sales 10.5" bbl, ported .086@ pistol position,65deg.F. 850' Elev.
8.5gr AA#9 cci 450 220smk-1008 1018 1031 1007 981 991 955 958 all cycled.
8.6gr AA#9 cci 450 220smk-1026 1051 1043 1054 1083 1067 982 all cycled.
8.7gr AA#9 cci 450 220smk-1011 1024 990 992 991 990 all cycled.
8.8gr AA#9 cci 450 220smk-1085 1065 1081 997 all cycled.
8.9gr AA#9 cci BR 220smk-1003 1054 1119 1034 1038 1028 all cycled.
9.1gr AA#9 cci BR 220smk-1096 1090 1084 all cycled.
9.1gr AA#9 cci BR 200smk-1087 1076 1095 all cycled.
8.7gr AA#9 cci 450 180 Horn sst - 1098, 8.8gr-1128,8.9gr-1097 all cycled.
17.5gr H110 cci BR 125 Rem sp-2008 2014 2048,18.gr-2099 2020 one FTF.
17.5gr H110 cci BR 130 Speer hp-1963 1995 2002,18gr1996 1960 1949 allcycled.
16.gr H110 cci BR 155 Berger VLD-1888 1899 1761 all cycled.
All loads shot with suppressor.All primers nice and round at edges, no ejector gouging,some case mouths dinged.

AM,

I think that you should post some photos of your SBR project. I always like to look a porn... gun pron that is. :grin:

Nice setup. I think I would have left the six pack out. I have a SSK suppressor and upper. Some people not in the know are a little uncomfortable around it. Mostly those who are not around firearems much. I had never converted apprehension for firearms into excitment and acceptance so fast until I started shooting a suppressed weapon. The lack of report seems to make it more palatable for some to shoot, and once they shoot it they are hooked. I hate to preach, but I think the picture sends the wrong message.

Attachment 405

Attachment 406
Stag Arms lower,M1S barrel with YHM QD 7.62. Assembled by myself.