United Defense Mfg Corp’s S7-PVAR and S7-DGIS are variants of the M110-SASS, Semi-Automatic Sniper System precision rifles chambered in the time-tested 7.62 NATO round (7.62 x 51mm) and designed to hit point targets up to 1,000 meters (MER). The S7 takes after the M110 battle rifle designed by Eugene Stoner. The S7 uses two action designs, the Direct Gas Impingement System (DGIS) and the patented Pneumatic Valve and Rod System (PVAR). The DGIS has a simpler design between the two as it has fewer parts and uses the hot gases coming from the gas port of the barrel and through a gas tube, the hot gases are rammed into the bolt carrier group to cycle the round.
The patented PVAR or Pneumatic Valve and Rod System are a “bare-bones, no-frills and very simple” designed gas and piston operating system that utilizes a combination of gas and mechanical energy for more effective and reliable cycling of the weapon. The PVAR design prevents hot and high-pressured gases from reaching the bolt assembly and the chamber. This results in a cleaner and reliable operation, as well as minimal maintenance even in the most rugged environments such as jungles, deserts, snow, and salt-water conditions.
This means reduced cleaning time and overall longer rifle life span. The S7-PVAR’s simplified parts and mechanism allow reduced recoil and reduced muzzle rise, which enables the sniper to refocus instantly on the target for each and every round fired! Furthermore, the PVAR allows the sniper to select if he wants to use the rifle in bolt-action mode or self-loading (semi-automatic) mode. Both the PVAR and DGIS models use a one-piece KeyMod Picatinny rail handguard held securely only at the barrel extension which allows the barrel to “float” and preserve barrel harmonics while in a battery.
This allows for greater accuracy and consistency. As designed, the barrel does not touch any part of the entire length of the handguard except at the barrel extension. For both the DGIS and PVAR, the barrel comes in different lengths: 14.5, 18, 20, 22, 24 and 25 inches. For special orders, UDMC can also produce the M110-CSASS or the “compact SASS”, with a retractable buttstock and with a barrel length of 14.5 or 16 inches for use by the spotter. The non-glare, matte finish of the stainless steel barrel is also an alternative to the standard carbon steel in black manganese finish.
Classification
- Precision Rifle
Country of Origin
- U.S.A. for the M110 (S7-DGIS) and Philippines for the S7-PVAR
Service History
- Launched in January 2014 for the S7-PVAR
Designed
- 2013 for the S7-PVAR
Manufacturer
- United Defense Mfg Corp, Philippines
Operating System
- PVAR gas and piston, rotating bolt head, Letters of Patent Nos. 1-2009-000176 and 1-2011-000062, Philippines or the DGIS, conventional direct gas impingement system
Bolt Carrier
- Monolithic one piece with a solid punch key for the PVAR and two piece with gas key for the DGIS
Cartridge
- 7.62 NATO (7.62 x 51mm)
Barrel Type
- Non-Glare, matte stainless steel bull barrel, AISI-416 Premium or the black parkerized carbon steel ordnance grade.
Barrel Length
- Choice of 14.5, 16, 18, 20, 22, 24 and 25 inches
Rifling
- 1 x 12 twist or 1 x 10 twist
Muzzle Velocity
- Approximately 2,600 ft/sec
Maximum Effective Range (22-inch barrel)
- 800 meters (point target) and 1,000 meters (area target)
Accuracy
- One (1) MOA using a M118LR ammunition at 100 meters, at bench rest.
Trigger
- Single stage, with option for two-stage for semi-auto precision use.
Flash Hider
- Choice of SHURIKEN flash hider (Letter of Patent No. 1-2013-000230, Philippines) or any type of tactical compensator or muzzle brake.
Weight
- Around 7.5 kg to 8.5 kg, inclusive of the floating KeyMod picatinny rail handguard, scope, bipod and a loaded 20-round detachable box magazine. Weight will be less depending on barrel length and type of scope.
Length
- 44 inches (22-inch barrel)
Rate of Fire
- Semi-automatic. (Note: However, when “Made-to-Order”, we can also produce the F7 battle rifle series which is the full automatic version for use by the spotter in tandem with the sniper who uses the semi-automatic version only.)
Feed System
- 10 or 20-round detachable magazine
Body Color
- Anodized black
Q – What type of ammo can your rifles use?
It can use any brand of M80, M118 and M118LR ammo. It can also use the commercial type of .308 ammunition.
Q – What are the maximum effective ranges (MER) of your rifles?
For the caliber 7.62mm NATO, 1,000 meters for the 22 inches barrel.
__________________________________
Maximum Effective Range (MER)
*To borrow a definition, MER is “The maximum range within which a weapon is EFFECTIVE against its intended target”. This would translate into the maximum range that the weapon could effectively put a man out of action.
______________________________
Q – What type of barrels do you use for the rifles?
We use only stainless steel 416 Premium or carbon steel in ordnance grade and duly certified from source or origin of the blanks as raw materials.
Q – Do you manufacture your own barrels?
Yes we do. We manufacture them from barrel blanks supplied to us by Dikar-Bergara from Spain. We are the Exclusive Distributor of Dikar-Bergara for all their products, barrel raw materials (blanks) including their bolt-action rifles in the whole of Asia-Pacific.
Q – What is so special about your UDMC barrels?
The Bergara cylindrical blanks are made from the finest carbon steel and 416 Premium stainless steel, used in the ordnance, aerospace and defence industries.
If other suppliers will claim that their barrels are SS-416, only a Certificate of Chemical and Mechanical Analyses can determine its quality. UDMC’s AISI 416 Stainless Steel PREMIUM ordnance grade barrel has contents of Vanadium, Nickel and Molybdenum which are not found on a standard AISI 416 stainless steel barrel. The net effect is that the UDMC-Bergara barrels have a yield strength of 780 MPa (versus 275 MPa of std AISI-416 SS) and a tensile strength of 920 MPa (versus 517 MPa of std AISI-416 SS). In terms of toughness, a UDMC-Bergara barrel is 73 Joules versus 34 Joules of the std AISI-416 SS.
The optimum combination of high hardness, yield strength, and tensile strength, along with the correct toughness, allow UDMC-Bergara barrels to withstand the generated pressures when the rifle is in battery, even with powerful rounds such as the .30 caliber precision rifles.
UDMC-Bergara barrels, compared with other stainless steel barrels in the firearms industry, are very hard steel which increases the mechanical properties of the barrels and it is fair to say that this is one of the best insurance from the safety point of view of a barrel. In addition to this, one of the differences of UDMC-Bergara barrels is the small grain size of its molecular structure thus guaranteeing excellent toughness. The homogenous microstructure during hardening and tempering provides a uniform hardness along the bar, producing a very uniform rifled bore, which is the key to accuracy of a barrel. The heat treatment, in combination with the precise deep hole drilling, honing and button rifling process results in a uniform finish of the bore under 0.0008 inches. The stress relieving heat treatment on the other hand, after the button rifling process, protects the bore from inside deformation after the tapering of the barrel. It also helps protect the barrel from heat generated after continuously firing several hundreds of rounds.
The same level of quality speaks of the UDMC-Bergara carbon steel barrels in durability, safety and accuracy.
Finally, the high chromium content of UDMC-Bergara barrels provides a good corrosion resistance to it.
Q – What is your warranty on the life cycle of your barrels?
20,000 rounds minimum under normal use.
Q – What raw materials do you use for the rifles?
We use T6-7075 for the upper and lower receivers, T6-6061 for the handguard (or thermoplastic) and buttstock tube. For metal parts, we use only 4140, 4150 and MIM-S7 for the small parts. Our barrels are made either of SS-410, SS-416 or 4150 Premium ordnance grade which has contents of Molybdenum, Nickel and Vanadium not found in other barrels which makes it double the tensile strength versus other barrels (FEBRUARY 15, 2019)
