|
||||||||||||||||||||||||||||||||||||||
Senior Member
Senior Member
Senior Member
Senior Member
What are the specifics on the rounds being fired? What is the twist of the barrel? Is the suppressor a 30cal? 5.56 + 7" barrel + suppressor = eventual baffle strike.
I'm not fat, I'm tactically padded.
Tactical Commander Fast Action Response Team (F.A.R.T.)
Senior Member
I've now had a pretty good chance to play with SIG's new 7" upper and wanted to share my thoughts. I really haven't bothered to try the upper for accuracy since I assume most people will be using this upper as a noise-maker or pistol upper. But I suppose I should shoot it for groups at 50 and 100 yards just to satisfy my own curiosity. If I have time, I'll mount my Leupold FireDot next week and give it a try.
Anyway, the upper is more than just a standard 516 upper chopped to seven inches. The gas block, upper and bolt/bolt carrier assembly remain the same but the gas parts are different. As you can see, the gas parts look alike when assembled with the exception of the overall length:
Note that the gas valve on the 7" model is, indeed, different. Gone are the small gas rings on the full-length system. These have been replaced with three grooves on the short system:
The piston assemblies are different as well. Note that the short piston lacks the small vent holes at the muzzle end of the cup:
The gas valve on the 7" model only has three settings. They are full-powered, suppressed and off. The upper will not run in the suppressed setting without a can in place:
Note the crazy short overall length of the 7" upper:
Even though the barrel and gas system is substantially reduced, the handguard lengths are similar. Note that the 7" model's rail telescopes over the gas block on the shorty. I like this and would like to see SIG extend the rail on the 16" model to cover the gas block. This would cover the bayonet lug but I don't think too many people would mind:
The short upper weighs roughly a pound less than its longer brother. Weights are about 4.75 pounds for the 16" and 3.75 pounds for the shorty. The reduced weight and changed center of gravity really makes for a handy little blaster.
I've been pleased with what I've seen from the SIG piston guns, for the most part. I've had good reliability from both lengths. The 7" upper runs fine in semi- and full-auto as does the 16" model. I don't care for the way SIG chose to secure the gas valves. These parts thread into the gas blocks and are held from rotation by a small detent. What I don't like is that the detent is very small and hard to depress without a cartridge or a punch and the gas valves themselves are hard to turn when fouled with carbon. I'd like to see SIG re-design the valves slightly and/or shorten the retaining detent a little so the shooter doesn't have to keep the detent continually depressed while unscrewing the valve.
The 7" upper is fun to shoot but the handgaurd's length is limiting even though it does extend around the gas block. The gas block is still exposed up top and I've found it very easy to burn a finger or thumb while shooting if not careful. A VFG is probably a requirement on such a short platform.
As soon as I can get some long range accuracy and some chrono data, I'll post an update.
Thanks for reading. Happy New Year!
Senior Member
Originally Posted by Jer
The barrel is hammer forged and chrome lined with a 1x7 twist.
The suppressor used in a Gemtech HALO. It wasn't used much due to concerns over baffle strikes.
Member
Tokarev, I really like how that looks and runs!
I just got paperwork back on a lower that I am going to run my 7" Noveske Diplomat barrel on. I only have about 500 rds through it now. I had to change the bolt gas rings once already. I'm wondering if a piston gun might be a better option in this length. I will have to see if this is going to be a problem in the future. I am running a KX3 Pig with 9" rail.
I need to shoot some groups W different grain bullets to see how stabilization is before I run my HALO on it. I would be interested in bullet stabilization in your 7" gun.
I'm going to run My 7" on my M16 lower on Monday to see how it functions.
Does anyone have information on gas ring life on Super short SBR's?
Until that day,
Darkop
Right or wrong, black or white. Cross that line, your gonna pay, but in the dawn before the light, we live or die by shades of gray.
Senior Member
Another slow motion video of the upper in use:
http://www.youtube.com/watch?v=Ik0VJ...eature=related
Last edited by Tokarev; 01-01-12 at 12:16.
Member
Is this due to lack of stabilization?
Senior Member
Correct. This is why I chose 300 Blackout for my new 9" suppressed upper because the 200gr projectiles stabilize sooner.
I'm not fat, I'm tactically padded.
Tactical Commander Fast Action Response Team (F.A.R.T.)
Posting Permissions
Reply With Quote
Bookmarks