Erin Go Big: .300 Blaser Magnum Barrel Block Beast from Ireland

Here’s one of the latest F-Class projects from Enda Walsh of Custom & Precision Rifles in Ireland. This rifle features a free-floated BAT Machines ‘M’ action with a Benchmark barrel chambered in .300 Blaser Magnum (300 BM). The barreled action is secured with a large barrel block. This handsome, long-wheelbase F-Class rig is “new-born”, but it has already demonstrated some stunning accuracy at 1000 yards. Enda tells us: “I couldn’t wait until the rifle was fully polished before testing. I went to MNSCI (Midlands National Shooting Centre of Ireland) to shoot my new barrel block rifle. I came home with a huge smile on my face after shooting a five-shot group with 1.5″ vertical and 3″ horizontal at 1000 yards in an 8 mph wind.”

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Below you can see the barrel block in the handsome Padouk wood and carbon fiber stock. Enda uses high-spec epoxy layered between the barrel and the aluminum barrel block. Yes, those three “super-sized” cartridges are .300 Blaser Magnums loaded with with 230gr Berger Hybrids. The smaller cartridge is a .308 Win (with 150gr bullet), provided for comparison. This .300 BM drives the 230s at 3140 FPS.

.300 BM Runs 230-grainers at 3140 FPS!
Enda tells us: “I wanted something to beat the 300 WSM. After studying the .300 Blaser Magnum, I decided this was the [chambering] that could deliver high accuracy consistently and be able to shoot the 230gr Bergers at 3140 FPS. Using H1000 powder, they do very well but the case life is short at these speeds. We have backed them off a little and retained the accuracy and extended case life considerably.”

Enda says the 230gr Hybrids at 3140 fps drift much less in the wind than do 7mm 180gr Hybrids launched from a 7mm WSM. A quick run through JBM Ballistics for a 10 mph, full-value crosswind at 1000 yards (sea-level) tells the tale. JBM predicts 4.2 MOA horizontal deflection for the .30-caliber 230s at 3140 fps vs. 5.0 MOA for the 7mm 180s at 3050 fps. That 0.8 MOA difference represents more than 8 inches at 1000 yards. When you consider the small size of the F-Open X-Ring, you can see how the enhanced ballistics could be a game-changer in the wind.

Barrel Block Acts as Heat Sink
Enda needed a way to beat the heat, with this big case. He explains: “Because of the large case volume (roughly 82 grains of usable capacity) there are two issues. Firstly, throat wear, and secondly heat. To combat this I have a new reamer on order with slight alterations which will help the throat wear. To combat the heat affecting a 34″ barrel I decided to build a barrel block rifle. It was previously mounted in a standard stock, and when the barrel got too hot accuracy was an issue. The barrel block acts as a heat sink and also shortens the overhanging barrel considerably, which has greatly improved accuracy over a complete string. The block is made from aircraft grade aluminium.” As a final note, Enda wanted to thank Pacific Tool & Gauge for the special-order reamers.

Note the metal bag-rider “keel” on the underside of the buttstock.