Target Sports

PROJECT RIFLE: A WHAT GUN?

Created on 14th May 2009

LAURIE HOLLAND begins a project to build a tube gun, starting with a look at the philosophy behind this concept

WHEN PRODUCING their foodie masterpieces, television's aspiring Masterchefs start with the best recipe they can find, select the finest ingredients the producers will provide - and only then will they head for the stove. Building an accurate rifle is really little different. Think long and hard in advance about which bullet and MV combination out of which length and rifling twist barrel are best suited to the discipline. Then (subject to budgetary constraints of course) choose the action which should offer the most consistent results. When we get to stocks, things become less simple as choices depend greatly on personal preference and shooting style as much as anything. Generally, it's best to avoid designs that require a different stance and hold from that used over the previous 20 years.

There is of course the ‘thundering herd' technique, in which lots of people switch to whatever last season's winner used. Remember that Michael Schumacher was reckoned to reduce an uncompetitive Formula One car's lap times by a couple of seconds when he first joined Scuderia Ferrari, and that sort of personal skill advantage often applies to top long-range shooters too. Anyway, this article is about the results of one set of choices with a new long-range .308 F/TR rifle as the objective, going through to the build and testing stages. As I'm no riflemaker, I had to enlist someone with the required expertise for the building part. As it turned out, this bit was surprisingly easy as Target Sports' Vince Bottomley happened to mention he was looking for a new gunsmithing project. Better still, he proved receptive, enthusiastic even, about a project for shooters on this side of the Atlantic - a tube gun. "A what gun?" most of you ask. Since this is the reaction of nine out of 10 people on hearing these words, I'll start off by telling you a bit more about it. This month we'll look at the philosophy and background behind this type of rifle stocking that changes the entire configuration of the shooting stick, and move onto the more mundane factors like bullet weight and barrel specs next month. Vince will finish off by taking over for the workshop part of the process. Actually, this isn't too far from the order in which things really happened, as I spent most time initially thinking about the practicality and implications of using different designs of tube gun stock, and only got around to factors like catering for light or heavy bullets once that was sorted.

Black rifle

Going back to the kind of rifle I'm comfortable with and the handling I was looking for, readers will have noticed I'm a fan of Eugene Stoner's ‘black rifle' or AR design. One of the many things I like about this is the ergonomics, much of which come from the straight-line layout, which has the bore and bolt positioned close to the rifle's centreline. The rifle therefore recoils more or less straight back into the shoulder, reducing muzzle rise and felt recoil. Throw in the AR's raked pistol-grip, excellent balance and a layout that puts the head and eye position naturally in line with the sights and you have a very user-friendly design.

These features are particularly valuable to gun-shy recruits and are in full-auto military use. They also provide benefits for us target shooters as consistency of hold, eye position and rifle movement under recoil are key elements in the accuracy mix. Target rifle stock designers are aware of these factors and have lowered the bore-line in their stocks, a good example being HPS-TR's System Gemini. However, take the idea further and you end up with the action and barrel completely inside a cylindrical stock. Hey presto, you've got a tube gun! Very clever in theory, but just how are you supposed to operate a manual bolt action when the receiver and bolt are enclosed? The answer is to have a longitudinal L-shaped slot in the stock body for the bolt handle to stick out of and travel along.

The tube gun has diverse origins - an important one is High Power Service Rifle, America's largest NRA-sponsored discipline. It seems everybody who has designed or made tube guns has a Service Rifle (SR) background. To be more precise, the breeding ground seems to be the Match Rifle (MR) division of Service Rifle. This is shot over the same four courses of fire as SR covering 200yd, 300yd and 600yd involving standing, sitting and prone positions with rapid fire and compulsory reloads in a couple. While SR requires conformity to the base M16 military rifle in outline and sights, MR allows much more freedom over the rifle specification.

Remington 40X and Winchester M70-based bolt action rifles with five-round internal magazines were long used for building MR rifles, achieving reloads with stripper clips. Come the 1990s, MR shooters looked at the accurised Service Rifle AR15s in use in the mainstream discipline, liked what they saw and developed their own radically modified versions. These had fully-adjustable tubular buttstock assemblies, slotted aluminium forend tubes, barrel extensions to extend the sight-radius and so on. Throw in bright colours and anodised or powder-coated finishes and these effective but unconventional rifles acquired the nickname ‘spacegun'.

T2K

Top MR shooters also wanted ammunition that provided better ballistics than the .223 Remington to reduce wind drift in the 300yd and 600yd stages, but which would still feed reliably and produce modest recoil. They looked at the cartridges employed in Metallic Silhouette competition including handloaded heavy-bullet versions of the .22-250 Remington, .243 Winchester, 6.5mm-08 Wildcat (since adopted by Remington as the .260R) and 7mm-08 Remington. These designs needed the larger Armalite AR10 or Knight's Armament Co. SR25 platforms, the ‘big AR' newly rediscovered after being forgotten for a generation. To cut a long story short, highly-modified big ARs were used successfully for a time, but were not completely reliable in operation, which is not uncommon when you change cartridges and barrel pressure curves in gas-operated weapons. Top rifle shooter and competition shooting accessory manufacturer David Tubb decided what he wanted was a marriage of ‘spacegun' layout and optimised bolt action operation, also picking up previous work on 6mm Wildcats based on the .250 Savage/.22-250 Remington case to produce his ideal ‘Across the Course' cartridge - the 6X and more recent 6XC.

The Tubb 2000 or T2K rifle was born, jointly designed by David Tubb and Rock McMillan, with McMillan's company McBros Rifles also manufacturing them. It is a straight-line design intended for 3-P shooting with an all-ways adjustable tubular buttstock assembly. It uses a nearly-circular section assault-rifle-style receiver incorporating an SR25 box magazine for rapid reloads. With the rifle assembled, the bolt body is nearly hidden inside the receiver, the bolt-handle root running through a slot which extends back into the buttstock tube by a couple of inches. The action is optimised for rapid fire, incorporating a very short bolt-throw with the knob positioned for minimal hand movement between it and the trigger. On top of that, a combination of clever design and ultra-precise locking surface machining allows such easy manipulation it is claimed that only a single finger is needed against the bolt-handle even for the unlocking and primary extraction work. Finally, the low bolt position lets the shooter keep his or her head firmly on the cheekpiece throughout bolt operation. This minimises rifle movement in relation to the target and maintains a consistent hold and sight picture throughout strings of rapid fire - a particular boon in the offhand and sitting stages. Lock-time is very small and trigger operation is precise using an Anschutz match trigger assembly, also designed to maximise scores in these stages, which are usually where matches are won or lost.

Tube kits

Although usually referred to as a tube gun, strictly speaking the T2K isn't one, because the bolt runs directly in the receiver as in a conventional action. A true tube gun is similar- looking and uses the same basic concept and straight-line layout, but incorporates a conventional action, more often than not the Remington 700 short model. The central tube section is therefore a stock-sleeve, not a receiver, and while it reinforces the action it is not pressure-bearing. The MAK Enterprises single-shot kit is typical, with five CNC-machined aircraft-quality aluminium alloy components plus various bolts and setscrews. The central section accepts a Remy 700 short action. It is slotted from the rear for the bolt handle and mounts the other four main parts: tubular handguard; aft-cap; trigger guard and Weaver sight-rail. The 700 action is located in the MAK tube by action screws, but the main securing agent is epoxy glue - JB Weld-recommended - so you won't get your action out easily! The trigger guard doubles up as the mounting base for an AR15 pistol-grip. The ‘aft-cap' does just what its name suggests, capping the back end of the main stock-tube section, and it provides the rear section of the bolt-handle channel. It mounts any AR15-compatible buttstock assembly; products available range from the cheap military M16A2 component to clones of the T2K four-way adjustable type. It is mounted on the central tube/action section by a precise butt and socket arrangement that allows easy removal and refitting without tools. This is how the bolt is removed from and replaced in the action, and is the way to carry out barrel cleaning. (It also means you can mount a 34" barrel if you want without having to invest in a super-length gun cabinet or carry-bag, as you can keep the rifle in two sections when not in use.)

CSS

However, I didn't choose the MAK kit, purchasing its competitor from CSS instead. This is an abbreviation of Competitive Shooting Supplies, Californian engineer and shooter Gary Eliseo's company. His B1 single-shot tube-rifle kit is identical in principle to the MAK example already described, but with significant differences in execution. Although most versions use the 700 action, the single-shot model is optimised for the very rigid and precisely-machined Barnard ‘Model P'. Secondly, the CSS stock doesn't need the action to be glued into the main stock tube, although Gary Eliseo says owners can do so if they wish. This stock relies on stock bolts plus the front edge of the action butting up against a substantial and stiff collar at the front of the main tube section. (The Remy 700 action has a smaller diameter receiver than the big Barnard, and Gary includes a circular recoil disk with 700 action kits. In effect this is a large precision-engineered washer that is inserted between the barrel shoulder and action, replacing the Remy recoil lug to effect the action lock-up in the tube.) Finally, the CSS kit includes a pistol grip, handstop (for MR/prone rifle shooters) and a complete four-ways adjustable buttstock assembly, for not much more money than its competitor charges.

Prone rifles and repeaters

As noted, tube gun stock designers and builders mostly have an SR/MR competition background. A one-off tube gun called the ‘funnygun', designed and built by noted SR competitor and gunsmith Bill Wylde, was the original inspiration for Kevin Macdonald of MAK Enterprises. It's ironic then that until very recently tube guns were all single-shot. They became increasingly popular with American Prone Rifle shooters, and many top competitors now use them. This is a medium to long-range slowfire discipline shot with sling support like our Target Rifle but with calibres and cartridges free, and a mix of iron and any-sights matches. Rifles are normally fitted with Weaver sight-rails to allow an easy switch between match sights and scopes. This was largely down to the difficulty of developing magazine versions, but MAK's solution came, as for many other small builders of repeating rifles, in the form of the Accuracy International detachable box magazine. Gary Eliseo took a more ambitious approach, developing a 6mm BR repeating version, the R5, from scratch using his own design of machined aluminium alloy single-stack mags. These hold five of the short, stubby BRs, giving perfect feed and top accuracy with light recoil - ideal for Match Rifle of course, and a much cheaper alternative to the 6XC Tubb rifle in both rifle and handloading gear.

Apart from the straight-line ergonomics, an often-quoted benefit of tube guns is the absence of conventional bedding, which is a source of inconsistent performance as well as an expensive item. Traditionalists may scoff at how well a magazine Remy 700 - even a trued and sorted example - would work when bolted into a bit of aluminium pipe, especially the CSS design with no glue-in. Gary Eliseo has few doubts on this matter, though, saying these rifles will shoot half-MOA any time, subject to cartridge choice and barrel specification. Those who might dispute this assertion received a shock recently. Veteran American Prone and Palma shooter Jerry Tierney discovered long-range benchrest late in life and has been cleaning up at 1,000yd. He acquired a CSS R5 repeating rifle kit and built himself a 6 Dasher (improved 6BR) MR rifle with a 700 action and Krieger barrel. With a Delrin ‘sled' bolted to the forend tube, a buttstock modification added to ride the bags and iron match sights replaced by a Nightforce NXS, Mr Tierney won the 2008 NBRSA 600yd National Championship at the Sacramento Valley range in April, beating 30 of America's top benchrest competitors using out-and-out bench guns. Even taking into account this gentleman's famous wind-reading skill and local knowledge of a notoriously tricky range wind-wise, it was an amazing performance from a rifle that had cost $1,960, or £1,000 in our money. The gun was actually built for Match Rifle, but has also been used successfully in Prone Rifle with iron sights in competitions out to 1,000yd. It weighs in at 14lb in this guise, and is just a couple of pounds more scoped and set up for benchrest.

I'll cover my CSS kit-based F/TR rifle specification next month, by which time the barrel will have hopefully arrived from the USA and Vince B will have started work on the build, as well as giving product details, prices, contact and website information for the various suppliers.