December 2nd, 2013

Slick F-TR with Adjustable Bag-Rider and Carbon-Metal Bipod

Forum member Jonathan L. (aka ‘Quest-QC’) was a member of the Canadian F-TR team at the F-Class World Championships in Raton, NM this fall. His handsome .308 Winchester rifle features some interesting hardware and a stunning African Padauk-wood stock stiffened with carbon fiber layers. We were impressed by the innovative, adjustable bag-rider assembly Jonathan fitted to the rear of his stock (scroll down for photo). With an Allen wrench, the vertical height and the slope (i.e. fore/aft angle) of the V-shaped bag-rider can be changed easily. This has many advantages. First, Jonathan can set his rifle to the most comfortable height (for his prone position) without using “lifters” under the rear bag. The system also gives him some gross elevation adjustment separate from the bipod. In addition, the angle adjustment allows the bag-rider to better match the geometry of the rear bag. Last but not least, by setting up the bag-rider with some drop (higher in front, lower in back), Jonathan can fine-tune his elevation (while aiming the gun) by simply sliding the rifle fore and aft.

F-TR F-t/r rifle starshooter .308 Win Winchester F-Class Berger Hybrids Adjustable stock bag rider Padauk African Wood Carbon Fiber Bipod

Jonathan says: “This year was my second year shooting at 1000 yards and I managed to find a spot on Team Canada for the FCWC at Raton. Here is the rifle that brought me there…”

F-TR F-t/r rifle starshooter .308 Win Winchester F-Class Berger Hybrids Adjustable stock bag rider Padauk African Wood Carbon Fiber Bipod

The rifle features a Kelbly Panda F-Class RB-LP action, 34″ Bartlein 1:11″-twist, Heavy Palma contour barrel. Fitted to the red-toned Padauk-wood stock is a 23.2 oz., StarShooter CF-SS light weight bipod with custom bench feet. On top is a March 8-80x56mm scope in Kelbly rings. Total weight of the rifle is 18 pounds, 1 oz., complete with the 24 oz. adjustable brass bag-rider at the back. The bag-rider block was modeled in 3D, then machined afterwards to use up the remaining weight available after all the other components. CLICK for StarShooter CF-SS Bipod Video.

African Padauk Wood is Very Stiff
Jonathan chose the red-toned African Padauk Wood because it is stiff for its weight: “The reason for choosing African Padauk is that the weight of the wood is the same as Maple but 45% more rigid.” The downside of Padauk, as Forum member Gstaylorg notes, is that it is a “very oily wood, which can make it somewhat difficult to finish with something like polyurethane. [Padauk] can generate a lot of bubbles and cause cracking problems around joints and/or seams.” Jonathan did note that he has observed a few bubbles in the auto clear coat on his stock. He plans to refinish the stock in the off-season.

F-TR F-t/r rifle starshooter .308 Win Winchester F-Class Berger Hybrids Adjustable stock bag rider Padauk African Wood Carbon Fiber Bipod

Gun Is Extremely Accurate with Berger 200gr Hybrids
Jonathan says this rig was very accurate, at least until his barrel gave up the ghost. He says he has put 15 successive shots in about 1/4 MOA: “I managed to make it twice (1/4 MOA for 15) by taking my time between shots. You don’t want to overheat this barrel. I needed to provide a very strong effort (mentally) to be able to achieve such precision as the rifle is way better than me.” Jonathan shoots Berger 200gr Hybrid bullets (in the lands) with Hodgdon Varget powder, and Federal 205M primers, loaded into neck-turned Lapua .308 Win brass. He has also had good luck with Vihtavuori N150 powder in the past.

F-TR F-t/r rifle starshooter .308 Win Winchester F-Class Berger Hybrids Adjustable stock bag rider Padauk African Wood Carbon Fiber Bipod

In compliance with F-Class rules, the adjustable bag-rider system would not be adjusted “on the fly” during record fire. The bag-rider’s vertical rise and fore/aft slope would be optimized before shooting, then locked in place. The bottom photo offers a good view of the V-shaped profile of the metal bag-rider. We have found that this kind of V-profile, closely matching the triangular profile of the rear ears, makes a rifle more secure in the rear bag and often allows the gun to track better.

F-TR F-t/r rifle starshooter .308 Win Winchester F-Class Berger Hybrids Adjustable stock bag rider Padauk African Wood Carbon Fiber Bipod

F-TR F-t/r rifle starshooter .308 Win Winchester F-Class Berger Hybrids Adjustable stock bag rider Padauk African Wood Carbon Fiber Bipod

Permalink Gunsmithing No Comments »
December 2nd, 2013

Tool Tip: Optimize Your Cutter Angle for Improved Neck-Turning

When neck-turning cases, it’s a good idea to extend the cut slightly below the neck-shoulder junction. This helps keep neck tension more uniform after repeated firings, by preventing a build-up of brass where the neck meets the shoulder. One of our Forum members, Craig from Ireland, a self-declared “neck-turning novice”, was having some problems turning brass for his 20 Tactical cases. He was correctly attempting to continue the cut slightly past the neck-shoulder junction, but he was concerned that brass was being removed too far down the shoulder.

Craig writes: “Everywhere I have read about neck turning, [it says] you need to cut slightly into the neck/shoulder junction to stop doughnutting. I completely understand this but I cant seem to get my neck-turning tool set-up to just touch the neck/shoulder junction. It either just doesn’t touch [the shoulder] or cuts nearly the whole shoulder and that just looks very messy. No matter how I adjust the mandrel to set how far down the neck it cuts, it either doesn’t touch it or it cuts far too much. I think it may relate to the bevel on the cutter in my neck-turning tool…”

Looking at Craig’s pictures, we’d agree that he didn’t need to cut so far down into the shoulder. There is a simple solution for this situation. Craig is using a neck-turning tool with a rather shallow cutter bevel angle. This 20-degree angle is set up as “universal geometry” that will work with any shoulder angle. Unfortunately, as you work the cutter down the neck, a shallow angled-cutter tip such as this will remove brass fairly far down. You only want to extend the cut about 1/32 of an inch past the neck-shoulder junction. This is enough to eliminate brass build-up at the base of the neck that can cause doughnuts to form.

K&M neck-turning tool

The answer here is simply to use a cutter tip with a wider angle — 30 to 40 degrees. The cutter for the K&M neck-turning tool (above) has a shorter bevel that better matches a 30° shoulder. There is also a 40° tip available. PMA Tool and 21st Century Shooting also offer carbide cutters with a variety of bevel angles to match your case shoulder angle*. WalkerTexasRanger reports: “I went to a 40-degree cutter head just to address this same issue, and I have been much happier with the results. The 40-degree heads are available from Sinclair Int’l for $13 or so.” Forum Member CBonner concurs: “I had the same problem with my 7WSM… The 40-degree cutter was the answer.” Below is Sinclair’s 40° cutter for its NT-1000, NT-1500, and NT-4000 neck-turning tools. Item NT-3140, it sells for $12.95. There is also a 40° cutter for the NT-3000 tool, item NT-3340 ($13.95).

Al Nyhus has another clever solution: “The best way I’ve found to get around this problem is to get an extra shell holder and face it off .020-.025 and then run the cases into the sizing die. This will push the shoulder back .020-.025. Then you neck turn down to the ‘new’ neck/shoulder junction and simply stop there. Fireforming the cases by seating the bullets hard into the lands will blow the shoulder forward and the extra neck length you turned by having the shoulder set back will now be blended perfectly into the shoulder. The results are a case that perfectly fits the chamber and zero donuts.”

* 21st Century sells carbide cutters in: 15, 20, 21.5, 23, 25, 28, 30, 35, 40, and 46 degrees. PMA Tool sells carbide cutters in: 17.5, 20, 23, 25, 28, 30, 35, and 40 degrees.

Permalink Bullets, Brass, Ammo, Reloading 6 Comments »