6mmBR.com SPONSORS

Tale of Two Rifles
Story and Photos by Greg Roche ("Caduceus")

The USA boasts some of the finest precision rifle-builders and Benchrest parts suppliers in the world. Before returning to Australia after two years in the States, I decided to have two special BR rifles built using American components and skilled labor. I wanted a matched pair--twin guns that would be as handsome as they were accurate. The heavier gun of the pair, the 13.5-lb Custom Class rifle, features top-of-the-line (but well-proven) technologies and components. With the 10.5-lb Traditional Class rifle, we had to develop new solutions to allow the 30BR cartridge to feed from a functional 2-round magazine. Here is my saga of how my twin 30BRs were conceived and built, and how they have performed in competition.

BACKGROUND -- The 30 BR for Score Competition The 30BR is a wildcat cartridge based on a necked-up version of the 6mmBR Norma case. It originated in US Benchrest circles where it found its niche in Varmint For Score (VFS) matches. Unlike traditional Benchrest, where group size determines the winner, VFS matches are shot on a target with multiple, concentric-ringed bullseyes. Point total is based on "best edge" shot location (one shot per bull). In score competition, the 30BR's "supersized" .308-diameter hole offers an advantage over the 6mm hole created by a 6 PPC, the dominant group BR chambering. VFS is not often shot at Benchrest tournaments in Australia. However, a similar format to VFS is Hunter Class Benchrest (HCBR). This match is rapidly gaining popularity Downunder. Like VFS, HCBR also uses the best edge scoring method so an ideal cartridge is one that is not only extremely accurate but also capable of punching decent-sized holes in the paper. Believe it or not, top shooters are capable of making perfect 250 scores over a 25 target match at each yardage with winners often being decided by X counts. Thus the 30-calibre advantage is real, not just theoretical. Under Australian rules, the 30BR appears ideal for HCBR. For starters, you have the undeniable "bigger hole" advantage compared to a 22, 6mm, or 6.5. Moreover, in Australia, there is NO minimum case capacity for Hunter Class, so the 30BR cartridge is legal. (Conversely, in the USA, a Hunter BR case must have the equivalent H20 capacity of a 30/30 cartridge; the 30BR comes up short.) Like the 6PPC, the 30BR offers great inherent accuracy, and great brass. The 30BR recoils harder than a 6 PPC, but recoil is still more than manageable for bench shooting.

Action Choice--Stainless Grizzly II from Kelbly's
The heart of any rifle is the action. Both my two 30BRs have RBLP Grizzly II actions from Kelbly's. Kelbly's is perhaps most famous for the Stolle Panda flat-bottomed aluminum actions but the Grizzly II also has a match-winning pedigree and precise tolerances. The Grizzly II is a round-profile, stainless steel, Remington-style action. I chose Right-Bolt, Left-Port configuration for ease of loading at the bench. The Traditional Class action has a magazine cut out in the floor and a plunger-style ejector (both required to meet the class rules). By contrast, the Custom Class action has a solid floor and no ejector. Other minor differences are the shape of the loading/ejection port and the profile of the bolt noses. The bolt from the single-shot action has a conical face, which theoretically gives maximum accuracy when mated to a similarly profiled barrel. However, the bolt from the repeater is made square for reliable pickup of the next round in the magazine without jumping over the top. Both bolt face diameters are 0.473" for .308 case heads and feature sliding-plate style extractors.

Both receivers have pinned recoil lugs. These are not always required in Benchrest actions since a square tang can perform the same role when the stock is inletted accordingly. Since the actions are pillar-bedded into their timber stocks rather than glued, and because the 30BR recoils more stoutly than the 6mmPPC, I decided to fit recoil lugs on both rifles. Jewell triggers are standard fare--both set at 2 ounces. Bolt stops are integral to the action as with most benchrest actions.

Gunsmithing Challenges--Feed and Ejection Problems in the Repeater
Getting the stubby 30BR cartridge to reliably feed and eject from the repeater action took some ingenuity. In reality, HCBR competitions are conducted as single-shot loading affairs but nonetheless, the rules state a functioning magazine is required. Firstly, the magazine supplied by Kelbly’s used a standard Remington 700 BDL short action (.308-length) box, spring and follower. Unfortunately, this magazine would prematurely release 30BR rounds at the start of the feeding stroke, which lead to jamming. I tried a .223 magazine box and follower instead. Although the .223 box has a block in the rear to shorten it, it was still long enough for the 30BR. However, the box was also narrower so now the cases would not properly stack on top of one another.

Traditional Class rifle has a functional 2-round magazine. Note position of bolt stop.

The solution I eventually found was to remove the block from the back of the .223 magazine box and glue it in place in the back of the wider .308 box. At the same time, the wider .308 follower was reshaped with a grinder and file to remove length from the rear and enable it to fit into the shorter box. For good measure, the vertical height of the magazine was also reduced so that only two rounds would fit and one leaf was removed from the follower spring to shorten it and change its thrust angle. The end result was flawless stacking and feeding of two rounds from the modified magazine.

30BR case just prior to clearance from the ejection port. The stubby case is cocked on a more acute angle than more traditional longer cases and requires a minor modification to the ejector to function reliably.

Ejection also proved problematic at first. Plunger ejector mechanisms cock the case sideways against the bolt raceway as it is withdrawn from the chamber after firing. The shorter the case, the more acute that angle and in the case of the 30BR, the cases would actually fall off the extractor before they cleared the ejection port. The solution was to modify the ejector to give it a longer stroke length. This was achieved by removal of the plunger and grinding a small amount off the rear portion of the groove that arrests its forward travel against the retaining roll pin. When done correctly, the uncompressed plunger sits slightly proud of front of the bolt and is able to retain the case head against the extractor despite the increased angle of the short case against the bolt raceway. This subtle modification proved to be all that was needed to get reliable ejection. The repeater action now functions as required and the rifle is legal for Traditional Class competition.

The modified ejector reinstalled in the bolt. The ejector face now sits higher than the face of the locking lug. After ejector modification, the case head is retained by extractor even at an acute angle.

Scope Options--6X for Traditional, 45X for Custom
Both rifles are fitted with Leupold scopes in Kelbly aluminum rings and bases. The Traditional rifle's scope is a 6x42mm to comply with class restrictions. It has a front-adjustable objective for parallax correction and a target dot reticle. I like the target dot when "holding off" for wind correction on the Hunter Class targets. The other rig wears a 45-power scope since magnification is unrestricted in Custom Class. It has a side-parallax adjustment and target dot reticle. The greater magnification really helps with precision aiming, and is probably the main reason why Custom Class scores are higher.

Gunstocks -- Modern BR Design in Lightweight Red Cedar
The handsome stocks were handmade by Richard Franklin of Richard's Custom Rifles in Virginia. This is Richard's own Benchrest stock design that meets all the dimensional requirements of the governing rules. He makes these in a wide variety of timbers but Red Cedar is the choice when weight savings and beauty are prime concerns. They are actually 3-piece laminates, not solid, single pieces of wood. Richard carefully aligns the grain between layers has been made to eliminate the possibility of warping. Richard’s bedding job reflects superb workmanship, and features handmade stainless steel pillars and escutcheons and skillfully-applied Devcon bedding material. The result is a rock-solid, stress-free bedding job. Both aluminum butt plates were hand-made by Richard and fitted in perfect alignment. The Cedar was finished with high-gloss polyurethane. The end result--rich red cedar matched with polished actions and barrels--is much admired by all that see this matching pair of rifles.

The chambers were both cut with the same reamer supplied by Dave Kiff of Pacific Tool and Gauge. Randy Robinett, the "father of the 30BR", specified the reamer dimensions. Randy's 118gr, 10-ogive custom BIB bullets and the 30BR cartridge enjoy a winning track record in the USA. The 30BR Robinette reamer has zero free-bore and a .330" neck, and is optimized for the BIB 118s. The bullets perform best when seated far enough out to jam firmly into the rifling as the bolt is closed. The long ogive means the bullet’s bearing surface is very short. The Traditional Class rifle is fitted with a 3-groove 1:17 twist Lilja barrel. From the outset, we knew that making 10 pounds max weight was going to be a challenge for a rifle with a steel action, a functional magazine, and wood stock. Red Cedar is a lightweight wood but not as light as fiberglass or other modern composites like carbon-fiber.

Careful calculation was needed to weigh all components and choose the right barrel profile so as to not go overweight. Fortunately, Dan Lilja has an excellent web-based barrel weight calculator. Using that, I determined that a Lilja “Hunter Class” taper, crowned at 22 inches, would be the correct weight once chambered and fitted. Lilja's calculator was spot on--the completed rifle weighs 9 lbs., 15.5 ounces.

Barrel weight was not an issue with the Custom Class rifle, given the generous 14-lb weight limit. The barrel in this case is a Shilen 1:17 twist, heavy varmint taper, finished at 24 inches. To compensate for the extra barrel weight, the fore-end of the Custom Rifle's stock is two inches longer than its lightweight brother. Some extra weight has also been added to the butt to maintain perfect balance and bring the final weight up to 13.5 pounds.

Slow Twists for Maximum Accuracy
You may note the unusually slow twist rate of both barrels. In most .30-caliber chamberings, the barrel twist rate is 1:11 or 1:12 to stabilize 150gr to 200gr bullets. The 30BR is optimized for 115gr to 118gr flat-base bullets and 1:17 provides sufficient stability at muzzle velocities around 2900-3000 fps. In competitive Benchrest, where every thousandth of an inch counts, over-stabilization of projectiles can hurt accuracy, so "just stable enough" is the goal; hence the 1:17 twist.

The starting point for loading the 30BR wildcat is Lapua 6mmBR brass. These are necked up as a single-step operation using a .30 caliber tapered expander ball (or dedicated expander mandrel). This will leave a bulge in the neck, so the expanded case neck must be turned to bring the thickness down to the correct dimension for the chamber. I turned these necks down to .010" wall thickness using a Stiller neck-turning tool. It features an eccentric mandrel similar to the Nielson "Pumpkin". Loaded rounds measure .328" neck diameter. This gives minimum clearance in my .330" neck chamber, so very little neck resizing is needed after firing. Cases are trimmed to 1.500" prior to turning to ensure consistency since the Stiller tool indexes the length of cut off the case mouth. Other than that, cases are just chamfered, loaded and made ready to shoot. No special fire-forming is required.

A Sinclair case neck micrometer indicates neck thickness of 0.010" after neck turning.

30BR dies are readily available from a number of manufacturers. I personally use Wilson neck and seating dies with a Sinclair Arbor press, but Redding and Forster both supply high-quality threaded dies for use in a conventional press. For under $100.00 US, custom full-length dies can be obtained from Hornady and CH Tool & Die by sending them reamer prints or a couple of fired cases. Harrell's Precision offers "semi-custom" dies. Just send them some fired cases and they select a pre-made CNC-cut die that ideally fits your chamber. You can ask the Harrell brothers for a die that's tighter at the shoulder or base, or otherwise customized to your preferences.

Load Development and Accuracy Testing
With cases formed and bullets selected, load development is simply a matter of choosing the right primer, powder and charge weight, and loading the most consistent ammunition possible. The Lapua BR cases use a small rifle primer. The choice here was Federal 205 Match primers vs. CCI BR4 Benchrest primers. Some shooters have also had success using CCI 450 magnum primers but it is very unlikely the small case needs this much spark to light off regular extruded powders. In my case, I selected Federal primers because availability tends to be better in Australia. [Editor's Note: Conversely, the Federal 205m primers are currently hard to find in the USA.]

The relatively large bore to capacity ratio of the 30BR case means that fast burning powders are the order of the day. Once again, US experience suggests H4198 (the Hodgdon equivalent of ADI AR2207) is the choice of match winners. The fact that H4198/AR2207 is an Australian-made product is an added bonus. So, I loaded up test rounds with AR2207 from 32.5 grains to 35.0 grains in approximately 0.3 grain increments. All bullets were seated to jam +0.010" into the lands. This places the bullet base about two-thirds of the way down the neck and well short of the neck-shoulder junction.

On a windy day at SSAA Belmont range in Brisbane, neither rifle disappointed. After a brief run-in and sighting session, the heavier Custom Class rifle proved a breeze to tune with every charge weight from 32.5 to 35.0 grains easily grouping five shots under half an inch at 100 yards. You’d expect nothing less from a custom Benchrest rifle. An accurate node was found at 34.6 grains with the best 5-shot group measuring 0.29". With less than 40 rounds expended and all loads made using virgin brass, the rifle was already showing its potential. That would suffice until better weather and an opportunity to shoot under match conditions presented itself.

A 100-yard group worthy of further testing was found using 34.6 grains of AR2207 (H4198) in the heavy Custom Class gun.

Next it was time to test the lighter Traditional Class rifle. At only 10 pounds, the rifle tended to jump around a little more under recoil. It also prefered a little shoulder pressure into the butt as opposed to the heavier rifle, which I shot free-recoil. The lighter barrel was also a little more sensitive to charge-weight variations but this was to be expected. With the limited testing time available, a satisfactory load was still found at 35.0 grains with a 5-shot group measuring 0.41". A milder load might be better since this is at the upper limit of what's being shot by US shooters, but several attempts at lowering the charge weight saw the group opening up. There were no signs of pressure noted on extraction or brass examination. So, for the time being, the lighter gun will use the slightly hotter load.

Super tight groups proved more elusive in the 10-lb Traditional rifle (see below). I think the vertical could be reduced with better recoil management. Still, this load provides a basis for further testing.