April 30th 2023Sunday gunday: Innovative 7mm-6.5×47 Wildcat from Jason BaneyJason Baney is one of the “founding dads” of our website, which began as 6mmBR.com over 18 years ago. Jason Baney created an interesting wildcat a few seasons ago, a midsized 7mm cartridge that was based on the Lapua 6.5×47 case. Jason (who works now at Eurooptic.com), talks about his 7×47 Wildcat and his initial velocity tests (and feasibility). Jason performed a multi-staged test to determine the 7×47 velocity potential. He cut a barrel into two-inch increments. A video is embedded below that shows the process. You may be surprised to learn that a 7×47 cartridge can drive a 180gr Berger Hybrid with a 32? Reloder 17 and a 32? Max Velocity of H4350 (and Reloder 17. The H4350 (and 32? With a barrel length of 24? The 7×47, with a 24? This is an impressive performance for a cartridge of this size pushing a large bullet. 7×47 Lapua Wildcat – Great Accuracy, Surprising VelocityBy Jason Baney Eurooptic.comWind is the biggest enemy of long-range shooting. It is also the most difficult to predict and gauge. It is impossible for mortals to defeat wind demons without a cartridge that has the highest ballistic efficiency. This cartridge must also have a combination of recoil, component consumption and performance on target. The 7mm bullets are the best compromise between all of these factors. 7mm bullets have a great BC-to weight ratio and provide enough impact energy in most situations. The recoil from 7mm bullets is also more manageable than that of heavier/larger projectiles of.30 or.338 caliber. The 6.5×47 Lapua cartridge has been my go-to since its release in 2006. I wanted a non-magnum short-action round that would give me the least amount of wind drift at 1000 yards. The 6.5×47 parent casing allowed for the 180gr bullets to be seated completely out of the neck, yet still maintained a length that could fit in a Remington short-action magazine. It is not necessary to change the small primer pocket because it has proven to be a winner. This combination has always provided reliable precision and very tight velocity spreads. A web search revealed that there was no information on a 7×47 Wildcat, so I would have to rely on educated guesses to determine the test loads. My initial assessment/prediction was that heavier 180gr bullets in the larger 7mm caliber would end up at a max load very close to a 140gr bullet in the parent 6.5 caliber. This assumption turned out to be very accurate. The performance goal for this cartridge was to move a 180gr Berger Hybrid faster than 2720 FPS to be able shoot inside a 6.5mm 14gr Berger Hybrid with 2900 FPS. (I was able achieve that 2900 speed with the standard Lapua 6.5×47). I also planned to test the 168gr Lapua Scenar, the 180gr Lapua Scenar, and the 162gr Amax. But the goal was to beat the 6.5140gr bullets with 2900 FPS. I thought the 180 Hybrid would be the best way to achieve this. Here are the Summary Test Results of H4350 and IMR 8208, for 180s and 168s. Two chronographs were used to measure speeds at nine (9) different barrel lengths ranging from 32? Click HERE to download the Excel Spreadsheet with Chronograph Summaries of All Load Tests. Since this cartridge was a total unknown, I thought it would interesting to see what performance the 7×47 could reach at different barrel lengths. We wanted to find the barrel length that would give the best performance for the cartridge/bullet combination. It was obvious that testing 8-10 barrels of different lengths was pointless because barrels perform differently. Not to mention, it would be expensive and wasteful. I decided to try a more radical test instead and cut a 32? I needed a reamer, dies and other parts before I could start. Dave Kiff, Pacific Tool and Gauge, was eager to start the project as soon as we spoke on the phone. My one-of-a-kind reamer arrived a few days after our conversation. Bob Ruch, a Forster employee who I’ve known for many years, was willing to create a few sets for me. Lapua provided some brass and Rock Creek Barrels sent an elegant 1:8.7? -twist 5-R barrel blank to be used as a sacrifice. I wanted the gunsmith to be a tactical rifle shooter who could appreciate the capabilities of the round down to its 16.1″ length barrel. I asked Wade Stuteville, a friend from Stuteville Precision, to help me. The rifle I chose for this test was Accuracy’s new AT rifle. This rifle is a reworked and updated AI AW, with a user-changeable barrel. I can change a barrel literally in under a minute. The machining that was done to make this function possible was brilliant and simple. It retains the barrel but allows it to be released quickly with a 4mm Allen key. The test would be very easy to conduct as no tools were required. My goal was to test as many different combinations of loads as possible without making the test too difficult to complete. I wanted to test the 180 and the 168 Berger, as well as several different powders that represented different burn rates. This would give me a good idea of how the cartridge will behave at different lengths. Hodgdon Reloder 17 and Alliant Reloder 17 were the two best powders based on my previous experience with the 6.5×47. These would be the main players. I also selected Varget, IMR 8208 and VV N550 in order to cover a range of acceptable burn rates. I also used my standard CCI 450 prime because it has worked well for me in 6mmBR and 6.5×47 cartridges since 2006. They are incredibly consistent but are also better able take high pressures without causing blanking. After selecting the powders, I ran ladder tests in order to determine the maximum loads for the 32″ barrel. Velocity Study – Cutting the barrel from 32? Velocity Study — Cutting the barrel from 32?
It took some mental gymnastics to create randomness in the test. The barrel was cut in 2″ increments, starting at 32″ and ending at 16.1″. Wade had scored each length to make cutting easier. Each mark was 1/8″ long, so when I reached 16 1/8″, the barrel could be re-crowned. Each set of rounds that would be fired for each cut were predetermined. They were laid out in a way that no load was ever followed by another. To keep the number of rounds under 200, Reloder 17 loads and H4350 are fired at each cut. The four other loads are fired at every other cut. Twenty rounds (4 loads of 5 rounds each) per cut were fired from 32″ to 18″, and at the 16.1″ final length, each of the six loads were fired. This is a total 190 test rounds. The barrel was cleaned both before firing the 24″ and 16.1″ lengths. I fired two fouling shots after cleaning each time to normalize velocity. The rifle was fitted with 3″ foreend attachment for 1000-yard benchrest competition and fired from my front rest of 40 lbs with a rear rabbit-ear bag. During the test, the gun never moved its position. However, the muzzle did move 2″ backwards with each cut. I used two chronographs to test the rifle. A Magnetospeed V3 (at all barrel sizes down to 16.1 inch) was attached at the muzzle of the Oehler35P, which was placed 10 feet away from the original 32-inch muzzle. After each round of firing the barrel was removed, and we poured ice water on the exterior and wrapped a damp towel around it to accelerate cooling. We used two C-clamps, a 2×4, and a couple of C-clamps to create a barrel vice while the barrel cooled. While the barrel was clamped we used a hacksaw to remove two inches. We then crowned the barrel using an RCBS deburring device for a nice finish. It took about two minutes on average to cut the barrels at each length.
The rifle dropped 3.2 lbs during the test on its way to 16? inches. The muzzle blast and recoil increased dramatically, from 32? The recoil and muzzle blast increased dramatically from 32? The groups on target were quite impressive, given that we weren’t really aiming for absolute precision and had rough-cut crowned. Many groups were one large hole, and several were within half-MOA – even when the final 16.1 was reached. Each load lost between 12,25-16,8 FPS per inch (loss per inch – LPI), over the course of the test. However, the rate at which the loss occurred varied depending on the powder burn rate and barrel length. LPI increased rapidly below 24″ barrels. The initial LPI was 0-10 FPS at the longest lengths, while the loss per inch at the shortest was much higher at 30 to 55 FPS! I will now break down the performance into three barrel lengths to consider in different disciplines. APPLICATION 1: 28-30″ barrel for 1000-Yard Benchrest
I will barrel a 1000 yard Benchrest rifle with this caliber to give it a fair try. I feel that a 28-30mm barrel length will be sufficient to achieve my goal. My goal will be achievable with a 28-30? There will be a slight increase in recoil, but it is not an issue with a 17-lb gun. The barrel will also have a longer life. Barrel for Sniper/Tactical Matches
I was hoping to get good results in tactical matches with a 22-24mm barrel length. It appears that it will be difficult to achieve the speeds needed with a 22-24? I need to gain a lot of speed to beat the 6.5-round, so I will try a longer throat. The longer throat will make the round longer, but not longer than the Remington 700 Internal Box. It is still short enough to fit in the Accuracy International AICS and AW magazines that are commonly used in the discipline. APPLICATION THIRTY: 16.1? Barrel for Compact/Concealed Sniper rifle with Suppressor
The 7×47 may be best suited to running with a short barrel, and suppressor. Most 16? Sniper rifles are designed around the.308 win round. The 7×47 is a significant improvement in ballistics over a.308 win in a 16″ bar. The 180gr Hybrid, at 2500 FPS, shoots inside the 175gr.30 caliber bullet at same velocity. Comparing the 7×47 to other nonmagnum rounds fired from a 16? The test was educational, fun, and moderately successful. I am eager to test this round to see what it can do.
The 6.5×47 Lapua always had a small diameter and tightly fitting firing pins to ensure best performance. Due to reliability concerns, this is not something that you would expect from a real-deal Mil/LE sniper rifle. I decided to give it a shot with the bolt as is. The results (blanked primes) were immediate, and dramatic. In the initial pressure test, every single load blanked primers by 10% less than the intended velocity goal. This was not encouraging. The hole that the pin traveled through was 0.084″. The large pin was very damaging to the smaller primers, even though the hole was not overly-sized. We decided to bush the firing ring. The hardened bolt head of the AI presented a problem. Wade Stuteville sent me the bolt back with a beautiful bushing job giving me a 0.06? Wade Stuteville returned the bolt to me with a beautiful bushing-job giving me a 0.065? This is what I have been using for a while in my custom 6.5×47 match rifles. This pin size is a compromise that will make it less likely to break and solve the primer-blanking issue. We also reduced the firing pin protrusion, from approximately 0.066″ down to 0.051″. This bolt and pin mod immediately solved the problem and I haven’t blanked any primers since it was modified. I reduced the test loads a little after finding the maximum safe loads to ensure I had no problems all the way through. At this point, group sizes were not measured at all. Only pressure signs were.Similar posts:Tags: 6.5×47 Lapua, 7mm-6.5×47, 7×47, EuroOptic, Jason Baney
