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The "Ranging Shot" Is A Regular Column In The IHMSA News
Published in The IHMSA News, the Official Publication of The International Handgun Metallic Silhouette Association
Published monthly except November/December - January/February
IHMSA on the web at http://www.ihmsa.org
Volume 13, Issue 8 September
 
  The Ranging Shot Email Todd:  TSPOTTI@worldnet.att.net
  With ( Comments or questions? )
Todd Spotti
 

     A couple of months ago I referred to the Nikon Fieldscope III as probably the best 60mm spotting scope around. I know the 80mmís are all the rage right now, but thereís a lot to be said about the 60ís, especially if itís a good one.

     For one, thereís the size issue. Bigger is often better, but not always. A big scope is, well, big. Therefore, itís harder and more awkward to carry around. It takes up more room in your shooting bag. Itís heavier, and heavier scopes mean that you need a beefier (more expensive) tripod to mount it on.

     To illustrate this point, I was spotting for a friend of mine recently who was using a light weight tripod for a relatively large scope. Man, this scope wiggled and shivered on the tripod every time I even thought of touching the focus knob. Additionally, every time a random gust of wind came along, it was the same story all over again. Trying to spot the targets while the image was jumping and bouncing around like a 52 Plymouth with no shocks was tough. This was a nice scope but itís size wasnít well matched with the capability of the tripod. Have you priced good quality tripods recently? A heavy duty model suitable for a big 80mm scope isnít cheap. In fact, theyíre darn expensive. Theyíre also heavy by design. So now this weight issue is getting even bigger. I wonít beat this point to death, but while the 80ís provide unparallel brightness and extra wide field of views, thereís a lot to be said for portability, ease of use, and yes, even lower price tags.

     The Fieldscope IIIís body is fairly compact, only 11 inches long. Itís also made of a metal alloy (no plastics allowed) but even so, it weighs in at reasonable 2.3 pounds. Itís fully weather proof, water proof, and nitrogen filled as well. Go ahead. Tie a rope around it and use it for a boat anchor if you want. Wonít hurt it a bit. The lenses are all high quality optical Nikon glass and are fully multi-coated. That means ALL the lenses in the scope are covered with multiple layers of optical coatings to enhance contrast, eliminate reflections, and allow the maximum amount of light through the system. It also means the lenses are so coated on BOTH sides - front and rear. A lot of scope makers will single coat or multi coat on just one side of the lens to save money. Or they may multi-coat on one side and single coat on the other. Thereís all kinds of ways to pinch a penny in the manufacturing process at the expense of performance. Not Nikon. You get the whole optical enchilada with nothing held back.

     Like many scope manufacturers, Nikon sells the scope body and the eye pieces separately. That way you can match the particular eyepiece you want to the scope. You have more choices then. If you want flexibility, you can go for a variable power eyepiece. If you want to save some bucks, you can go for a single power eyepiece. Choice is always good.

  Itís also important to know that the quality of Nikonís eyepieces is perfectly matched to their scope bodies. Like the bodies, the eyepieces are also fully waterproofed and the lenses are also fully multi-coated. However, this isnít always the case with other manufacturers. Be very careful if you should buy another brand of spotting scope. That other guyís eyepiece may not be waterproofed and multi-coated unlike the scope body. Some other manufacturers will skimp here. Itís not unheard of that during rainy humid conditions, that the eye piece on lesser scopes will fog up while the body will be perfectly clear.

     When using the Fieldscope, thereís a lot to like. For instance, thereís a huge rubberized focusing ring located in the middle of the scope body. This eliminates any fumbling around when focusing while your eye is glued to the glass. Thereís also a very effective sliding sun shade. Image quality is Nikon excellent and thereís plenty of eye relief so guys like me that wear glasses can see clearly without having to press our cheaters directly against the eyepiece. Edge to edge definition is as good as it gets and the brightness is the best Iíve seen in a 60mm.

     With spotting scopes however, besides brightness, resolution, or the ability to distinctly see small details, is paramount. To evaluate this, I again used the homemade resolution chart that I described in last monthís column. This is just a series of ďOísĒ laid out in rows in type sizes varying between 72 and 12. In other words, the top row would have a series of Oís in large 72 type. The next row would be in 48 type. The third row in 36 type etc. Anyone can make one of these charts with their home computer. The idea here is to identify the smallest type size that you can see distinctly. Any size smaller than that will appear in the scope to be barely recognizable as Oís, and anything even smaller, will appear just as a fuzzy solid line.

     The Fieldscope did very well in the resolution examination. 24 size type was clear and distinct with no ambiguity and even 18 size type was recognizable. I compared this to another 60mm scope that Iíve used extensively and have always been completely satisfied with - the Bausch & Lomb Discoverer, which allowed me to see .224 sized holes in my 200 meter cardboard practice targets. The best the B&L was able to resolve distinctly was 36 size type.

     In a somewhat more practical evaluation, I took the Fieldscope to my local range where thereís a set of power lines running 300 meters beyond the ram berm i.e. 500 meters off. This distance has been confirmed by my friend Ron Sadler who owns one of those big Swiss- made optical artillery range finders. I then set the variable powder eyepiece on 20X.

     The temperature was in the mid 90ís and so there was plenty of mirage in the image. Never the less, I was able to clearly see that each ceramic insulator on the distant pole had five horizontal ribs down its length. With the B&L scope I couldnít see any ribs at all, much less count them. I then pointed the scope at a truck stopped at a dumping station in a rock quarry 1000 meters away. With the Nikon I could see that the driver was in the truck and that he was wearing a white T-shirt and a red baseball hat. With the B&L, I couldnít tell whether there was a driver in the truck or not. The Nikon works.

     Lastly, thereís the Nikon warrantee. The Fieldscope is warranted against defects in materials and workmanship for 25 years. Not bad. Also, if you should happen to accidentally drop your scope off the edge of your balcony ten stories up (your fault, not theirs), Nikon will fix your scope for only $10. Pretty good deal.

     In summary, the Fieldscope III is a premium quality product thatís more than a pretty face and a fancy name. It delivers high quality performance at less cost than the 80mmís and in a more user friendly, nicely compact package. It fits.

     If the price of the Fieldscope III doesnít fit your budget, then take a look at Nikonís 60mm Earth & Sky spotting scope. Not as many features, but nice price.

Some Basic Ballistics
     Bullets flying through the air are subjected to some very interesting forces, some of which are counter intuitive. Yet, for the serious handgun shooter an understanding of some of the basics is important so we can tailor our loads to best fit our needs. This is especially true when it comes to the choice of using either flat base or boat tail bullets.

     When a flat base bullet is whistling along through the atmosphere, itís moving aside a volume of air equal to its own volume and thus creates a partial vacuum immediately behind its base. As they say, nature arbors a vacuum and the surrounding air then rushes into this area. The air collapsing at high velocity into this vacuum creates turbulence at the base of the bullet - lots of it, and that turbulence creates drag - lots of it. In fact, at velocities below the speed of sound (1100 fps depending on altitude, temperature, etc.) that turbulence is THE number one source of drag on the bullet and will do more than anything else to slow it down even if it should have a blunt nose like a typical revolver silhouette bullet.

     At speeds above 1100 fps, base drag is still a factor, but another situation raises its ugly head to slow our bullet down even more. At supersonic velocities, the air is being compressed ahead of the bullet faster than it can be displaced. It then gets compacted into a dense shock wave thatís pushed ahead by the nose of the bullet. In other words, the bullet is now trying to fight against an even thicker layer of air. Result? Yep, more drag and more velocity lost. Nose drag now becomes the number one source of our diminishing velocity although base drag is still doing its thing as well.

     So, what can we do about it? Well we can taper the base of the bullet. Boat tails on commercial bullets will still have a flat base but now itís much smaller and so while thereís still going to be some base drag, itís going to be much less than if the base was the full diameter of the bullet. Additionally, the boat tail is going to smooth the air flow around the base in a much more smooth and orderly way and so will also reduce turbulence. Ideally, a pointed boat tail would be the ballistically optimal design, but I suspect there are manufacturing difficulties in producing such a base.

     Now that weíve reduced base drag, what can we do to reduce or eliminate that nasty nose drag? Simple. Use velocities less than 1100 fps. That way the shock wave is totally avoided because you never create it. And when shooting at less than 1100 fps, how do you reduce base drag as well? As we said before, use a boat tail bullet.

     Sound familiar? Yes, this is the classic J.D. Jones 300 Whisper principle i.e. shoot 220 grain 30 caliber boat tail bullets at subsonic velocities in a fast twist barrel. In a previous article I did on the Whisper I found that when fired at a velocity of 1050 fps, a 220 Sierra boat tail would lose only 67 fps at 200 meters. Only 67 fps! At 200 meters! Why so little velocity loss? Drag, or more properly, lack of drag.

     A boat tail makes all the difference in the world. While it will reduce drag at all velocities, it actually has the greatest effect at subsonic velocities. Consequently, boat tails are a more important design feature at subsonic speeds (where theyíre hardly ever used) and at long ranges (where the bullet slows down to subsonic velocities before it hits the target) than at fast speeds. (J.D., youíre one very smart guy.) A boat tail is far less effective at supersonic speeds (where it is always used). Doesnít make much sense, but there it is.

     This whole situation sounds ideal for a heavy cast bullet with a boat tail as regular commercial jacketed boattails are usually pretty expensive. However, no one I know makes such a mold because you canít put a gas check such a bullet. However, a gas check isnít really needed, since the idea is to never go over 1100 fps. Sounds like a interesting project for someone. Anyone interested?


Sinclair International Calendar

     Here it is the middle of July and Iíve already got a new calendar for 2003. You probably think Iím nuts to get one so early, but this particular one is special. No, itís not from any of the publishers of the various girlie mags, but rather from Sinclair International - home of the precision reloaderís catalog super store. The name of the calendar is ďRifles: Past & PresentĒ (Yes, I do own and shoot rifles as well as handguns, but donít tell anyone.) This thing is gorgeous with exceptional photography of vintage, competition, and varmint rifles along with the story behind them. It sells for $14.95 and is perfect to hang over the reloading bench. Iíd be a nice gift for your father-in-law as well. Check it out and visit them at their web site at  
http://www.sinclairintl.com

JB Bore Paste
     Not too long ago I was digging around in my closet and came across a very old TC barrel chambered in 7 TCU that I hadnít used in several years. I kind of wondered why I had neglected so long so I loaded up some ammo and headed out to the range. The barrel shot fine. I was in kind of a lazy mood and when I got home I neglected to clean it. The following weekend I took the barrel out again and this time the results were just so - so. Again I neglected to clean it. The third time out, the groups were terrible. ďWhat happenedĒ I wondered. Same load, same everything, and now the groups were embarrassing. A quick look at the bore revealed the problem. The tops of the lands were loaded solid with copper fouling. The inside of the barrel looked like the stripes on a candy cane. The fouling was as bad as Iíve ever seen it on a barrel. Now I remembered why I didnít use that barrel very often.

     I tried cleaning the barrel with a standard bore cleaner and all it did was take the top layer of copper off. Next I switched to a copper remover liquid, and it took another layer off still leaving plenty behind. Thatís when I got out the JB. I should have used it from the very start.

     JB is an oily paste with some kind of gritty material embedded within. Just smear a dab on a patch and work back and forth through the bore. The gritty stuff completely breaks down to super fine dimensions and gently cleans the copper right off of the lands without any scratching or scraping. A later examination of the TC barrel showed the lands to have a zillion horizontal cuts across the tops - undoubtedly from a rough bore reamer. The bores on some of those early TC barrels could sometimes be pretty nasty.

     Anyway, the JB removed the copper fouling in a flash. Just follow up with regular bore solvent to clean the JB residue out of the bore and youíre finished. JB is also great for removing moly build-up and cast bullet leading as well. If youíve got a tough bore cleaning job to take care of, JB is the best. You can get it at Brownellís. Visit them at
http://www.Brownells.com. Lots of great stuff and THE most comprehensive gunsmithing catalog in the world. I love looking through that thing just to see all the neat stuff thatís in there.

Good luck and good shooting. Todd

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Warning: All technical data mentioned, especially handloading and bullet casting, reflect the limited experience of individuals using specific tools, products, equipment and components under specific conditions and circumstances not necessarily reported in the article or on this web site and over which IHMSA, The Los Angeles Silhouette Club (LASC), this web site or the author has no control. The above has no control over the condition of your firearms or your methods, components, tools, techniques or circumstances and disclaims all and any responsibility for any person using any data mentioned. Always consult recognized reloading manuals.