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November 15th, 2007

Lyman Electronic Digital Trigger Pull Gauge on Sale

We’ve used this Lyman gauge, and believe that it is the best product of its kind on the market currently. It is accurate and repeatable, and easy to use (with a bit of practice). Using modern electronic strain gauge technology, the Lyman tool measures pull weights from 0 to 12 pounds, with accuracy of ± 0.10 ounces (one-tenth of an ounce.). The battery-powered gauge is equipped with a large, easy-to-read LCD display and is push-button operated for zero, clear, and averaging functions. We’ve tested this gauge back to back with conventional coil spring trigger scales made by other manufacturers. The Lyman electronic gauge is faster, and in our opinion, significantly more repeatable. Some of the metal spring gauges tend to “stick” in a position, which requires multiple attempts to avoid a reading that is slightly high or low. The Lyman is more fool-proof to operate by contrast.

Lyman Electronic Digital Trigger Pull Gauge

Now through the end of November, MidwayUSA has the Lyman Electronic Digital Trigger Pull Gauge on sale for $41.99, item 220725, Lyman product #7832248. This includes a vinyl storage case, but you have to purchase the required 9-volt battery separately.

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November 13th, 2007

Magnum Drop Port from Oz

There was a lot of interest in Jeff Rogers’ Heavy Gun, featured in yesterday’s Daily Bulletin. Jeff is a race-car mechanic and engine builder in Australia, and you’ll find many innovative mechanical features on this rifle.

1. Drop Port for Magnum Case
Jeff reports: “The action is home-made. My shooting buddy Tony Z was the magician here–without his extensive machining experience, the action would still be on the drawing board. As you can see it is a Right Bolt, Left (loading) Port design. What makes it unique is the big gravity port, perhaps the only Drop Port ever made for a case of this size. The port will work will cases up to 2.850″ in length, with a .550″ max rim diameter.” The action is constructed from Swedish 709m chrome-moly steel measuring 2.00″ diameter x 10″ in length. It has roller-assist extraction to help with the high pressure loads Jeff runs. The action is both conventionally bedded and glued into the stock.

2. Removeable Aluminum Side Pods
The two alloy “side pods” were milled from 6061 T6 billet. Given airline weight limit of 32 kg per piece, Jeff made the pods modular (they are through-bolted), so the gun can be air-transported in two sections. Concerning the dual side-pod design, Jeff observed: “[This] is unconventional… but I wanted was something that was true [when bolted together]. Milling the thing up on every surface insured this and the pods are installed with dail indicators on assembly.”

3. Tension Barrel System
The Broughton barrel sits inside a threaded barrel sleeve that holds the barrel in tension. Tensioned barrels have been used on Heavy Guns before, but few have been as successful in competition as Jeff’s rig. Jeff tells us: “The 30-cal barrel is a 1.500″-diameter, 1:13 twist, 32″ Broughton. It is straight for 6″ then tapers to 1.250″ at 32″. The tension tube is 6061 T6 alloy 2.0″ outside diameter with a .187″ wall thickness. At the chamber end, a 431 stainless adaptor is fitted to the barrel, about 1.5″ long, stepped to a slip fit inside the tube for another 1.5 inches. This allows the main heat area of the chamber to sink into the tube. The tension tube is all jointed with a CAT high-temp anti-seize. On the muzzle end is a left hand 1.250x16tpi thread to take the tension nut. We have tried various tensions and found torque settings do not matter to the groups as long as the nut does not come loose. Because I can really rattle down those 10-shot groups with the Drop Port action, remember that the barrel grows in length before it gets a chance to transfer heat to the outer tube. If you shot the gun at pedestrian pace, then only 50 ft/lbs of tension is needed.”

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November 7th, 2007

NEW 6.5 Creedmoor Cartridge from Hornady

Hornady has announced a new, 6.5mm cartridge designed for Across-the-Course and High Power shooters, and 3-gun competitors. (We think the new round may also prove very popular with hunters and tactical shooters.) Dubbed the 6.5 Creedmoor, the cartridge is smaller than a .260 Remington (.308-size case) but larger than the 6.5×47 Lapua. Measuring 1.920″ from base to mouth, 6.5 Creedmoor brass features a 30° shoulder and minimal body taper. Case capacity is “right around 53.0 grains of H20″ according to Hornady. The 6.5 Creedmoor uses a large rifle primer and large flash hole.

Hornady 6.5 Creedmoor

Hornady says its 6.5 Creedmoor is designed to operate at “standard” .308 Winchester pressures, for increased “barrel and case life”. The 6.5 Creedmoor factory ammo is loaded to “under 60,000 psi” according to Hornady engineers. That’s quite a bit less than the 62,000 psi SAAMI max pressure limit for the .308 Winchester, or the 63,090 rated max psi of the 6.5×47 Lapua. Compared to max-loaded 6XC or 6.5×47 cases, the lower-pressure 6.5 Creedmoor should, theoretically, provide good barrel life. Dennis DeMille, who has been testing the factory 6.5 Creedmoor ammo, reports that the factory ammo is “not on the ragged edge at all–pressures are ‘sensible’, with excellent reliability as a result.”

6.5 Creedmoor Loaded Ammo Specifications

Bullet	COAL (max)	Powder	Grains	Primer	Velocity	PSI
120gr Amax	2.820″	H4350	43.5	LrgR	3020 fps	under 60,000
140gr Amax	2.820″	H4350	41.2	LrgR	2820 fps	under 60,000

The new cartridge looks speedy on paper. Hornady claims its factory-loaded 6.5 Creedmoor ammo will deliver 3,020 fps with the 120gr Amax and 2,820 fps with the 140gr Amax from a 28″ barrel. Those velocities are at the extreme high end of what we’ve seen a 6.5×47 Lapua deliver with 123gr and 139gr Scenars. In the 6.5×47, with handloads, it’s more realistic to expect 2950 fps with the 123-grainer, and about 2800 with the 139. Lapua’s factory-loaded 6.5×47 rounds are considerably slower. So, it appears the 6.5 Creedmoor will enjoy a slight velocity edge over 6.5×47 handloads, and a sizeable speed advantage over Lapua 6.5×47 factory ammo (with similar bullet weights).

BALLISTICS: 6.5 Creedmoor vs. .308 Win vs. .223 REM

Background of Cartridge
The new cartridge was conceptualized by Dave Emary, Hornady’s Senior Ballistician, and Dennis DeMille, General Manager of Creedmoor® Sports and two-time NRA National High Power Rifle Champion. Dave and Dennis wanted to provide factory-loaded ammo that would be 100% competitive with any High Power chambering, including the 6XC and 6.5×47 Lapua. The 6.5 Creedmoor was purpose-built for match rifles, including the Tubb 2000 and DPMS/Panther Arms LR Series. Its case is shorter than the 260 Remington, so you can load even the longest bullets into .308-Win length magazines. Pushing a 120gr Amax at 3000+ fps, the 6.5 Creedmoor offers a nice, flat trajectory plus good wind-bucking ability. Dennis Demille has used the prototype cartridge for many months now in a Tubb 2000 rifle. He says, the load is “moderate and very reliable. There have been no issues with stiff bolt lift or primer cratering.” The factory ammo runs “under 60,000 psi” according to Emary, and uses Hodgdon H4350 powder–43.5 grains with the 120 Amax and 41.2 grains with the 140 Amax.

Loaded 6.5 Creedmoor ammo is slated for release in January or February 2008 “at the latest”, according to Dave Emary. Ammo should be priced about $22 per box of 20 rounds, roughly the same as Hornady .308 Win match ammo. Brass, produced by Hornady in the USA, should be available by late spring. The new 120gr Amax bullet should be released very early next year.

DOWNLOAD 6.5 Creedmoor Illustrated Brochure

6.5 Creedmoor Specs