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Post by mike454 on Mar 27, 2020 20:31:27 GMT -5
Definitely an interesting question. Don't recall reading about bullet shape making a difference so much as bullet weight and velocity, though wouldn't surprise me if it did. My recollection is that the barrels natural inclination is to want to shoot apart hence them being set to converge in order to get them to shoot parallel. I would assume changes to loads that cause loads to converge or diverge in a SxS would do the same in an OU. At the end of the day, I don't know but the Seyfried articles might shed some light if all else fails.
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Post by flyingzebra on Mar 27, 2020 21:35:09 GMT -5
The most influential feature of bullet shape with regard to double rifle regulation is length of bearing surface.
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Post by bradshaw on Mar 28, 2020 7:13:30 GMT -5
First thing to note. The SxS double rifle when properly regulated shoots the right and left barrel groups in parallel trajectories. The trajectories do not converge or cross but as they open over distance they do overlap. Next, there are a tremendous number of small bore double rifles which are built for medium game and driven game hunting. These rifles tend to be quite accurate. I know of one Austrian 300WM SxS double rifle that puts R and L barrels into a MOA group out to 300 yards with 200gr softs. I have lusted after that rifle for years, and some day I might own it. In the build of a fine double rifle the barrels are often bored and cut rifled in house. They are then profiled and checked/corrected for matching taper and wall thickness. So yes, the barrels start out as similar to each other as possible. The term regulation refers to the build of the rifle. The builder/s will adjust the relationship of the barrels to each other until they shoot properly in a trial/adjust/trial process until the job is done. Making ammunition for the rifle (later down the road) is an exercise in getting the rifle to shoot to regulation. Some rifles will actually list the load prescription on the rifle itself. Also, there are rifles with adjustment provisions on the barrels which permit the adjustment of the barrel regulation. ***** flyingzebra.... interest information, in need of explaination. My curiosity is arroused, not satisfied. Item* Left and right barrels are regulated to shoot parallel, not to converge at a set distance. Thus, in theory at least, two STRAIGHT BULL BARRELS (some bull barrels taper) laid side-by-side should shoot parallel. * “I know of one Austrian .300 Winchester Magnum Side-by-side double rifle that puts Right and Left barrels into a Minute of Angle group at 300 yards with 200 grain softs.” As a group represents three or more shots, a group from a double rifle must represent 6-shots. Six shots into 1-inch @ 3 football fields is an amazing feat, I think any winner of the Wimbledon Cup would agree. Given perfect neutral light, no wind, and allowing barrels to cool between shots, a full description of equipment and shooting is in order. Please excuse my skepticism; in tone it sounds like this accuracy is available “on demand.” While the concept of consistency has a home in my vocabulary, “on demand” does not. David Bradshaw
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Post by flyingzebra on Mar 28, 2020 9:37:34 GMT -5
The barrels of a double rifle are typically not assembled parallel. The double rifle is shot from the shoulder of a man, not ever from a solid mount. Upon firing, the double rifle is lively, and as the barrels are off the central axis of the rifle, the rifle swings right from the right barrel and left from the left barrel - buynot by much. Also consider that fit is important, and that in some cases a rifle that shoots properly for one fellow won't shoot properly for another, given significant anatomical differences.
I've never seen a bull barrel on a double rifle. I've seen some relatively heavy profile barrels on 577, 600, and 700 double rifles where the heavy walls were used to give the rifles weight, but never in the bench rest or target match kind of distinction. A double rifle is a hunting rifle.
MOA at 300 yards would be roughly 3" That Austrian double rifle's muzzles are about 7/8" apart. It's a high grade chopper lump box look ejector rifle. It won't likely shoot across the course at Camp Perry with the match rifles - and no one is shooting strings of ten out of a double rifle. It is accurate though, and it is consistent. For what it's worth it's fitted with a low power variable scope.
Compared to an accurate bolt rifle, it's accuracy isn't much to speak of, and for a double rifle, it's remarkable. I have a 450 double rifle that's very accurate and very consistent, which prints it's groups at barrels' width with the proper load - and those groups are *very* good, but there's nothing more than very simple iron express sights and with that rifle I wouldn't waste the powder to find out what it does at 300
And bedding - perfect bedding is critical to the function of a properly regulated double rifle.
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WARDOG
.30 Stingray
Retired.....mostly.
Posts: 199
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Post by WARDOG on Mar 30, 2020 22:14:05 GMT -5
About ten years ago I was a machinist/barrel smith in JRH's shop when it was still in California. I am a machinist not a gunsmith. Jack was building a couple of double rifles at the time. One was a .450-400 from scratch in which we machined the mono-block from billet steel (4130). Jack had a very simple method of regulating the barrels (sorry cannot disclose that secret) but he regulated them within three shots from each barrel. It regulated with the right barrel shooting 'zero' at 50 yards, and the left barrel was about 3" to the left and high about 1" at the same distance. Not bad for a double. Another double we built was based on an English SxS 10 gauge frame. The customer wanted three sets of barrels for it. A .500, .600 and .700 Nitro Express. Regulating those barrels was much more difficult and time consuming due to the recoil moving the temporary barrel fixture. That was a multi year project. Several of us in the shop test fired the barrels into the pond behind the shop. The .500 was manageable, the .600 was ridiculous and no one wanted to shoot the .700 A-Squares at 1000 grains. We ended up strapping the .700 into a wooden sled he had and pulling the string. After they were regulated and finish soldered into place we proof fired the barrels and that wooden sled got pretty lively. I never got to see the final product as I had to take some time off for back surgery. Jack did maintenance and repairs for his PH's double rifles. I don't remember the PH's double manufacturer but it was elegant at one time. Imagine buying a $80,000 double rifle, then carrying it into the bush everyday for the last ten years. It had a lot of character.
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Post by dlbshooter on Mar 30, 2020 23:22:09 GMT -5
Shooting the British Double Rifle: A Modern Guide for Load Development by Graeme Wright.
The Bible for loading and shooting a double rifle. Load data, Cordite conversion wt. to modern smokeless powders, use of fillers. Excellent explanation of how a double is regulated and how to work up modern loads in rifles regulated with cordite. Etc. 1st, 2nd, 3td editions
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Post by squawberryman on Apr 1, 2020 18:09:12 GMT -5
Once upon a time I had the joy/frustration of shooting bats off of a Honda three wheeler on the waters edge with a blued receiver Red Label 20 gauge. That, was a hoot.
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