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05-08-2009, 11:30 PM
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#1
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68Forums.com Industry Partner
Join Date: Dec 2008
Posts: 291
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New Uppers
Today is range day! I'm taking the following with me:
The first upper is the most basic, 20" with threaded muzzle, Phantom .308 FH, Bushnell 3-15x50 scope and rifle length gas system. The second one is the 20" unthreaded with intermediate-length gas system.
The first upper in this photo is an 18" with a Saylors Machine Phoenix FH and mid length gas system. The bottom one is an 18" with a TNW gas piston system and DPMS Levang linear compensator. I'm really looking forward to trying out the GP system.
Range report will hopefully follow soon.  |
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05-09-2009, 02:37 AM
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#2
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68Forums.com Team Member
Join Date: Apr 2008
Location: Fort Worth, TX
Posts: 2,854
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Quote:
Originally Posted by carnaby
Today is range day! I'm taking the following with me:
The first upper is the most basic, 20" with threaded muzzle, Phantom .308 FH, Bushnell 3-15x50 scope and rifle length gas system. The second one is the 20" unthreaded with intermediate-length gas system.
The first upper in this photo is an 18" with a Saylors Machine Phoenix FH and mid length gas system. The bottom one is an 18" with a TNW gas piston system and DPMS Levang linear compensator. I'm really looking forward to trying out the GP system.
Range report will hopefully follow soon. |
Looking forward to the range work.
__________________
NRA Life Member
TSRA Life Member
If you're looking to purchase a 6.8 SPC rifle, upper, or barrel, you should consider SPC II, and 1:10 or slower twist as the minimum acceptable specifications. There is no reason or advantage to purchase a 6.8 SPC product that utilizes the obsolete 6.8 SPC SAAMI chamber. The extra leade in the SPC II or similar chamber lowers pressures which is beneficial to the wear and tear on your firearm. Lower pressures at a given velocity, or increased velocities at a given pressure are the benefits of using the improved SPC II type chambers.
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05-09-2009, 02:40 AM
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#3
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68Forums.com Team Member
Join Date: Sep 2008
Location: NH some of the time...
Posts: 5,464
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looks nice, agreed on the range report.
__________________
Arms discourage and keep the invader and plunderer in awe, and preserve order in the world as well as property... Horrid mischief would ensue were the law-abiding deprived of the use of them.-Thomas Paine
"I figure we are gunman because we are better then most, and it beats branding cows or digging copper" -Appaloosa
Do you know John Galt?
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05-09-2009, 04:38 AM
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#4
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68Forums.com Industry Partner
Join Date: Dec 2008
Posts: 291
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Just got back. Here's the results so far:
1. didn't spend much time with the piston upper as I was in a hurry and shooting at 100 yds didn't leave much time to sight in the irons sights. Three shots, cycled perfectly, move on to next upper (will come back to the GP on another day).
2. 18" barrels shoot great. Gas port is #45 (0.082"), all loads kick out right around 3-4 oclock, and accuracy is great. Most groups right around 1" without trying very hard or worrying about loads. Best group was 1/2" three shot with 85 gn Barnes TSX over 30 gn H322.
Also shot 110 gn Nosler Accubonds with H335. 29 gn and no pressure signs. 29.5 gn and primers were flattened. With 110 gn pro hunters I went to 30 gn H335 without any high pressure signs.
3. 20" barrel with intermediate length gas sysetem and 0.082" diameter port tends to short stroke on everything but loads using H335. I'm going to open up the gas port to a #43 and try again tomorrow. Accuracy is excellent as with the 18".
4. 20" barrel with rifle length gas and a 0.082" diameter port short strokes on everything, and won't even cycle. I'm going to open this one up to #42 (0.0935") and try again tomorrow.
So far so good, just need to find the gas port diameter that works for the 20" barrels. I'm headed back to the range tomorrow morning.
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05-09-2009, 09:42 AM
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#5
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Gone
Join Date: Jul 2007
Location: NJ
Posts: 2,419
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I don't want to say I told you so, but I told you that you should use the Mid length gas system with the 20" barrels. LOL.
Sounds good though, although I'm surprised you had pressure signs with the H335 and the Accubonds.
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05-09-2009, 10:17 AM
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#6
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68Forums.com Team Member
Join Date: Jul 2008
Location: South Georgia
Posts: 1,678
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Sounds like pretty good results so far Carnaby. Did you ever decide on whether to go with a SPR profile for the 18 in bbl, so the OPS, Inc comp would work?
__________________
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05-09-2009, 12:04 PM
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#7
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68Forums.com Team Member
Join Date: Apr 2008
Location: Fort Worth, TX
Posts: 2,854
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Quote:
Originally Posted by ron169
Sounds like pretty good results so far Carnaby. Did you ever decide on whether to go with a SPR profile for the 18 in bbl, so the OPS, Inc comp would work?
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Hey Ron.. It's on Bison's website that the next batch will have the SPR profile with the OPS cuts. I just spotted it yesterday myself.
__________________
NRA Life Member
TSRA Life Member
If you're looking to purchase a 6.8 SPC rifle, upper, or barrel, you should consider SPC II, and 1:10 or slower twist as the minimum acceptable specifications. There is no reason or advantage to purchase a 6.8 SPC product that utilizes the obsolete 6.8 SPC SAAMI chamber. The extra leade in the SPC II or similar chamber lowers pressures which is beneficial to the wear and tear on your firearm. Lower pressures at a given velocity, or increased velocities at a given pressure are the benefits of using the improved SPC II type chambers.
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05-09-2009, 01:14 PM
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#8
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68Forums.com Industry Partner
Join Date: Dec 2008
Posts: 291
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Hey guys, paulosantos in particular, I goofed. Turns out I was in such a hurry to get to the range that I mis-aligned the gas block on the upper with the rifle-length gas port. It was only exposing about half the gas port, which explains why the bolt wouldn't cycle at all, no matter which loads I used. 
Given what I found with the correctly aligned intermediate port, and a lot of the comments by Constructor in other threads, I decided to go ahead and open up the port on the rifle length gas barrel anyway. I'm headed back to the range in the morning, everything carefully aligned this time. Will post later in the day. |
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05-09-2009, 02:35 PM
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#9
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68Forums.com Team Member
Join Date: Sep 2008
Location: NH some of the time...
Posts: 5,464
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Carnaby, hav you tried any of the 85 grain SSA loads in your uppers? that would be the real test to see if they will cycle or not...
__________________
Arms discourage and keep the invader and plunderer in awe, and preserve order in the world as well as property... Horrid mischief would ensue were the law-abiding deprived of the use of them.-Thomas Paine
"I figure we are gunman because we are better then most, and it beats branding cows or digging copper" -Appaloosa
Do you know John Galt?
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05-09-2009, 08:30 PM
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#10
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68Forums.com Team Member
Join Date: Apr 2009
Location: Iowa
Posts: 192
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Your Barnes 85 gr. load
Carnaby what was your OAL on the Barnes 85 gr. TSX with 30 gr. of H322? Those uppers are lookn nice can't wait to try out the 6.8
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