Centurion Arms M12 Complete Rifle. Home Firearms Mk12 Complete Rifle. Availability: Usually Ships in 4 to 6 Weeks. You save. Rating Required Select Rating 1 star worst 2 stars 3 stars average 4 stars 5 stars best. Email Required. Review Subject Required. Comments Required. Trigger: Required View Options C. The lowers supplied were mostly MA1 lowers with Knights Armament match triggers installed and fixed butt stocks.
Upper receivers Use a standard Mil-Spec type 3 hard coat anodizing. The receivers have M4 style lowered feed ramps built in to enhance reliability as well as the rail interface numbering system on top Barrel An inch, threaded muzzle, match-grade, free floating, stainless steel, heavy barrel with a rifling twist is a standard for the SPR.
The barrels are manufactured with a special contour to maximize accuracy and to minimize weight. An OPS in. These barrels were designed to take advantage of the new Mk cartridge, which uses a grain bullet. Handguards A free-floating forearm is used, which does not touch the barrel directly. This increases the accuracy of the weapon by removing vibration and pressure exerted on the barrel by the rest of the gun.
Ammunition The SPR is not used to fire standard issue 5. Related Products. Add to Cart.By Melvin Ewing April 3, When the USA entered the global war on terror inthe various special operations branches of the US military soon discovered that they needed a weapon that would slot between the M4 and the M24 Sniper rifles in order to give the groups a bit more reach without having to resort to the heavier and slower bolt action sniper rifles.
The decommissioning of the M21 and failure to adopt the XM25 on a wide scale basis plus their larger size, partially lead to the gap in capability with the available weapons systems at the time.
The M24 was great for delivering long range precision fire, but the special operations teams needed to be able to deliver a lot of precision fire at ranges beyond the capabilities of the M4 and M16 rifles, and at a much faster rate than the M24 could deliver. The size and weight were also a factor as the rifles needed to be more portable for use in the dynamic war zone the teams found themselves in. The envisioned role for this rifle would be something similar to a Designated Marksman, but tailored for special operations.
The SEAL teams were the ones that were the most proactive in moving this initiative forward. Each armorer had their own little tweaks and mods that they preferred so the Recce Rifle was a bit different between each of the teams.
The basic concept was an M4 with optics and some parts to improve accuracy to allow more precise shot placement at longer ranges than their M4s were capable of. As the concept gained acceptance, the Naval Surface Warfare Center used their Crane Division to begin working on a formalized version of the Recce Rifle.
The SPR went through several developmental iterations before the specifics were settled on and the initial batch of Mk 12 Mod 0 rifles were fielded in The Mk ammunition was developed to enhance both the lethality of the 5. The barrel also uses the longer rifle length gas system that reduces gas pressures and slows down the bolt cycle for longer life and improved reliability. The length of the barrel is somewhat lengthened by the addition of the Ops Inc.
Upper receivers were all flattop M4 uppers made by Colt with some others used from Diemaco and Armalite. The lower receivers were also Colt made with some others labeled GM Hydramatic. One of the interesting things about the lower receiver is that they used old MA1 lowers on all of the SPR rifles so the original rifles had the MA1 or A2 fixed buttstocks and standard A1 or A2 grips.
Over time as the different versions of the SPR rifles were introduced, the buttstocks and grips changed a bit, but the receivers were all still MA1 receivers.
The trigger group was changed out to a Knights Armament 2-Stage full auto match trigger to improve accuracy. This too was changed out in later versions to the Geissele SSF trigger which proved more reliable. The heavier 77gr bullet allowed for the rifles to maintain that accuracy to ranges reaching beyond yards. The combination of rifle, suppressor, ammo, and skilled operator made for a lethal package for many engagement scenarios.
Because these rifles were developed for, and extensively used by the Special Operations units, these units freely made their own changes and requested their own specific optics and other parts be used on their rifles. The field modifications were not limited to just the optics either.
From Crane, the rifles came in a Pelican hard rifle case with cutouts for all of the accessories including the rifle, optics, suppressor, magazines, cleaning kits and other odds and ends. This change was one which many operators complained about.
There were several other changes included in the Mod 1 as well. The SPR was reported to have been made to very high tolerances and was much more reliable than the more mass produced M rifles.
It had even gotten to the point where the teams horded them like gold for as along as possible.
The history of the SPR is fascinating and they were used extensively in combat so they come with a proven combat record as well. Some people may even go so far as to say the SPR was the pinnacle of the Ar15 development over the last 50 years. What ever your personal feelings are about the SPR, they were a very effective DM style rifle with confirmed kills out to and beyond yards. All from a light and compact M16 based rifle. That rates as pretty high in our book.SPR initially stood for Special Purpose Receiverbut that nomenclature has been replaced as the weapon became a stand-alone weapons system, and not just an add-on upper receiver assembly part of the proposed SOPMOD upgrades.
The SPR was eventually type-classified by the U. Navy as the Mk Army and U. Navy, is a heavily modified light designated marksman variation of the M16 line of infantry weapons, chambered for NATO standard 5. Different U.
Mk12 Mod 1
Photographs, including both U. Department of Defense photographs and privately obtained photographs, consistently show most U. Army Rangers have been identified as using the Mk 12 Mod 1 version. All of these upper receivers are flat-topped, but have been seen with either the old-style teardrop forward assist or the newer round style.
When the SPR program was still just an upper receiver assembly and not a complete rifleCrane assembled all of its prototypes using either M16A1 or M4A1 lower receivers, because the full auto trigger group in these lower receivers provided a consistent pull while the more common 3-round burst trigger groups didn't. It is unknown whether this pattern continued as the rifle evolved.
There is also some issue about whether, when the Navy type-classified the weapon, Precision Reflex Incorporated PRI began assembling the rifles themselves. While a number of trigger options were tried in the end, the Knight's Armament Company KAC 2-stage trigger was finally decided upon as the standard. In all cases a free-floating forearm is used, which does not touch the barrel directly. This increases the accuracy of the weapon by removing vibration and pressure exerted on the barrel by the rest of the gun.
Due to the relative modularity of the system, optics as well as almost everything else can be mounted according to the operator's wishes. However, SPRs are most often seen with a 3. Night vision devices can also be attached. These scopes usually come with flip open dust covers and a honeycomb anti-glare anti-reflection device. Nightforce Ultralite 1. Originally the relatively expensive Parker-Hale swivel bipods were used, but were taken off the system after the initial SPR [ citation needed ].
The OPS Inc. The equivalent product is currently manufactured by Allen Engineering Co. It is substantially the same suppressor design and actually built by the same individual, Ron Allen, who previously fabricated the 12th model suppressor for Ops, Inc. The SPR is not used to fire standard issue 5. The newer load was designated Mk Mod 1. In lateSierra introduced a tipped version of this bullet which adds a polymer tip to improve ballistics.The genesis of the Mk 12 was the desire in some quarters for an accurate but not heavy these things are relative sniper rifle.
But, not every job calls for a. As if. In addition to the optics and the loaded magazine, the already-bipodded rifle gets more gear. Add a sling. Add a laser targeting designator.
Add a suppressor. The rifle is soon up to or even over 20 pounds, and that is before the end-user starts stuffing loaded magazines into his tac vest. All that gear will add to the full-up weight of a 5. And in order to do that, they must be accurate. Start with a ready-to go lower, because that is not unusual. Oh, someone will, but ignore him. The first thing you have to do is source a barrel. To gain the most accuracy from it, it should be properly bedded into the upper receiver. You can do fine just bolting it in, but to wring the last few bits of accuracy out of it, go with the full-on barrel installation as described in the barrel chapter.
The nut also includes a rear locking cap. Put the cap on, then the barrel nut, and tighten the barrel nut. The Gen II has a locking nut that is the same size as the tube, but the process is the same. You have to get the nuts precisely aligned, for gas tube clearance and to align the top rail and receiver with the handguard rail.
This is where you want to be careful and precise. The handguard aligns on the barrel nut. The handguard also has to allow for the top rail to be bolted across he handguard rail and the upper receiver rail. Keep adjusting and checking until there is no disagreement and the two rails handguard and receiver are in agreement that they are straight and will smoothly be clamped by the top rail.
Use a strap wrench to tighten the barrel nut cap. Then install the top rail and clamp it down securely. If you want, you can use blue Loctite or paint-in the nuts once tightened. The top rail uses five screws. Three of them go across the top, through the slots of the receiver rail. Two others go down from the top of the top rail and screw into the rail of the handguard.
Install the rear sight and paint it in as well. Next up, range trip. Use common, inexpensive ammo, and if you are in favor of this process, use the opportunity to break in the barrel. Ideally, you do this at the gun club, with the range to yourself, and on a nice, sunny, dry day. Make sure your rear sight is at the exact center of its adjustment range. Load one round, use the iron sights, an aim at an obvious mark on the hill.By Tom Beckstrand.
Tactical Operator shootingtimes. Where Crane, the Creator of the MK 12, should have left well enough alone. We had a handle on sniper rifles and machine guns, but we had one hell of an operational seam laying between our M4 carbine and the sniper rifles.
The M4 works well for general running-and-gunning duties out to about meters. Generally equipped with a holographic or red dot sight, the M4 is a wise choice for every man on the team. When we stretch the distance past meters, our choices at least in the fall of quickly became limited. Neither option is a great choice. Crane, with the input of our special operations soldiers, determined that an accurized 5. The greatest improvement that the SPR has over a traditional M4 is the barrel.
The barrel is made by Douglas Barrels and is an inch, button-rifled twist with a rifle-length gas system. Douglas also only uses its premium barrels for the Mk No barrel is ever perfectly straight, but the premium barrels on the Mk 12 are the straightest ones Douglas has and are probably much straighter than anything on a factory-produced rifle.
Douglas ranks with Broughton, Pac-Nor and Shilen as the most distinguished button-rifled barrel makers in the industry. The Douglas barrel on the SPR also has a rifle-length gas system.
The long gas system offers a couple of substantial advantages over shorter- length systems. The first and greatest advantage is that it has substantially lower port pressure than carbine- or mid-length gas systems. As a bullet passes down the bore, the pressure behind the projectile drops because the volume the gas has to fill is increasing.
The closer the gas port is to the chamber of the barrel, the higher the pressure at the port will be. Pushing the gas port of the Mk 12 all the way down to a rifle-length system means it will have the lowest pressure possible for an AR-pattern rifle. Port pressure matters because it determines how fast the bolt and bolt carrier cycle and operate. When we first started experimenting with carbine- length systems, we found that the extractor needed some modification to handle the increased cycling speed of the carbine system as a result of its much higher port pressure.From the Vault: Replica MK12 Rifle from Lone Survivor
The higher pressure made the bolt carrier and bolt move faster, and that increased speed caused the extractor to fail. Hence the birth of the SOPMOD kit that puts the little rubber donut around the extractor spring to give it the additional resilience against wear. Fast bolt issues have largely been fixed with the carbine-length gas system, and they make for supremely reliable guns.
A slow bolt is a happy bolt. It will last longer and give you fewer problems in the long run. The SPR has the longest-length gas system possible, to give the shooter the least maintenance-intensive firearm that will run for the longest amount of time. This is the variant that we had on my first Special Forces team, and it was a popular rifle among my teammates. The PRI fore-end has plenty of length for positional shooting and still leaves enough space for the addition of sling swivel mounts, lasers and night-vision equipment.
The SPR fore-end also has a continuous top rail that makes it possible to mount a scope in traditional rings forward enough to give the shooter proper eye relief. Made of carbon fiber, aluminum and steel, it is an excellent combination of light weight and strength. The round shape of the fore-end is definitely the way to go for a rifle destined for combat use.
Round fore- ends tend to be much slimmer than the traditional quad rail, even before we slap rail covers all over the quad rail to keep it from biting into the support hand when using a sling or carrying the rifle for extended periods of time. Then Crane screwed up with Mod 1.
Sigh I wish you could see me rolling my eyes as I write this. The big problem with the Mod 1 is the hand-guard. The PRI fore-end was greatly superior. If you look at pictures of soldiers carrying the Mk 12 in combat, pay attention to how they mount their scopes on the Mod 0 versus the Mod 1. You can find a lot of sweet action photos on mkExploratory Examination of Correlation Matrices. The main disadvantages are: Mean substitution artificially decreases the variation of scores, and this decrease in individual variables is proportional to the number of missing data (i.
Because it substitutes missing data with artificially created "average" data points, mean substitution may considerably change the values of correlations.
To index t-Test for Independent Samples Purpose, Assumptions. To index t-Test for Dependent Samples Within-group Variation. To index Breakdown: Descriptive Statistics by Groups Purpose. To index Frequency Tables Purpose. To index Crosstabulation and Stub-and-Banner Tables Purpose and Arrangement of Table. You can produce "double categorized" histograms, 3D histograms, or line-plots that will summarize the frequencies for up to 3 factors in a single graph.
Batches (cascades) of graphs can be used to summarize higher-way tables (as shown in the graph below). Siegel and Castellan (1988) express the relationship of the two measures in terms of the inequality: -1 More importantly, Kendall tau and Spearman R imply different interpretations: While Spearman R can be thought of as the regular Pearson product-moment correlation coefficient as computed from ranks, Kendall tau rather represents a probability.
FEMALE MALE COKE PEPSI SPRITE COKE PEPSI SPRITE X X X X 2 2. The deadline is December 31, 2017. Read more at our Admissions site about exciting changes to our programs of study. Employment The Department has openings for a Co-Director of Undergraduate Studies, Associate Professor, Assistant Professor, Wm. Kruskal Instructor, and Assistant Professor for the Computational and Applied Mathematics Initiative.
Applications are accepted at the Academic Career Opportunities jobs site. Best wishes to our department's Autumn Quarter graduates. After surviving Fall Finals, prepare for the wonders of winter and all the holidays of light welcoming in the New Year by joining us for the Department's Holiday Party on Wednesday, December 6, 5:00-8:30 pm, in the Ida Noyes 3rd-floor Theatre, 1212 E.
RSVP here by November 22. Jackson (PhD candidate in English), have been selected to receive a Graduate Collaboration Grant for their project "Social Movement and Media Narrative: Statistical and Machine Learning Analysis of Socio-political News Coverage.
Michael Dawson (Political Science) and Peter McCullagh (Statistics). Congratulations to our Harper Fellow. Statistics PhD Vivak Patel has been awarded the prestigious Harper Dissertation Fellowship for 2017-18. The University-wide competition awards financial support toward the completion of the candidate's dissertation. Faculty Professional Service Honor Prof. Per Mykland, Robert Maynard Hutchins Distinguished Service Professor, is the new president of the Society for Financial Econometrics for 2017-19.
Michael Stein Awarded the Arthur L.
Performance AR: Build a Mk12 Mod 0
Michael Stein has been awarded the Arthur L. Kelly Prize for exceptional service in the Physical Sciences Division. The Kelly Prize will be awarded at the PSD Convocation ceremony on June 10. The Statistics Consulting Program The Department of Statistics Consulting Program is now open and receiving project requests for the new academic year.
Degree in Computational and Applied Mathematics The University of Chicago has recently approved a new degree-granting Ph.
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Mk 12 Special Purpose Rifle
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