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I have a few of the Sightron 2.5x32mm (1"-tube) scopes. ExacTrack. Those are longer in mounting length than the Leupold Ultralight, not as light, but might be a rugged enough scope for full kick, extended use. Works on Bobbarrella in CZ rings, with no objective lens compression!  Rip ... | |||
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Nominee for The D. Carson Award.  Not recommended of course but just for grins and giggles I should increase the powder charge in my .458 WM 350gr TSX load to see if I can get to 2700 fps muzzle speed. For my barrel contour, calculated barrel hoop stress level at bore surface where it's maximum is about 1.4x chamber pressure. For the typical AISI 4140 steel barrel (and Rockwell C hardness of about 25), yield stress is around 110ksi. So for a chamber pressure of 65,000 psi, barrel hoop stress level is getting very close to yield. Need to beware - potential for stress cracks to develop at bore surface if yield stress level is exceeded. | |||
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4sixteen, "I have hope for the 350-grain TSX load that had Sd of 0 fps for 3 shots. MV = 2663, 2663, 2663, with H4198 78.0 grains, WLRM, 3.440" COL, and hBN." That was a 100% fill with drop tube. I estimate my maximum charge of 81.0 grains of H4198 was 104%, compressed, by use of drop tube. If you do not use hBN, pressure and velocity will be higher for any given powder charge. But if you use hBN, pressure falls off more than velocity, so if you jack the pressure back up, by adding more powder, you can get velocities higher than without hBN. I am a believer. You might get up to 2700 fps MV with a 23" barrel. For BC = 0.271, at 2700 fps MV, the 5-yard instrumental velocity was about 17 fps slower (16.8 fps) under my local conditions, 41*F, etc. So I would add 17 fps to a 5-yard chronograph reading to get MV when close to 2700 fps MV. Your 5-yard correction should be adjusted for local conditions of barometric pressure, altitude, temperature, relative humidity. Bob got over 2750 fps with 80.0 grains of H4198 in a 25" CZ barrel, no hBN on his 350-gr TSX bullets. Quoting Bob from his latest blog entry of 2019: **************************************************************************************************** Here are a few early results from the CZ: 500gr Hornady/ 81 grs H4895/ WLRM/ COL = 3.53″/ Win brass/ MV = 2283 fps/5786 ft-lbs 350gr TSX/ 80 grs H4198/ WLRM/ COL = 3.44″/ Win brass/ MV = 2760 fps/5919 ft-lbs (I shot a bear with that load.) http://www.bigbores.ca/ **************************************************************************************************** He also said he even went higher than that, but hesitated to publish that, no doubt thinking about kids who might not use the usual caution in starting low and working up. "Kids, don't try this at home without adult supervision." Rip ... | |||
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Thanks RIP, my education into the arcanery of these matters is long and slow. Somehow I missed noticing the c and its implications. That a 100% powder fill in any but slow-burning powders might constitute a maximum load had previously only occurred to me as a concept applying to black powder. Did Bob apply that criterion to the other powders as well? Is part of the superiority of extruded powders that their angularity at the cut-off is a meeting point less likely to stick to the next granule than the squished roundness of ball powder? Obviously, your experience with drop-tubes has been more successful than mine. I've tried a two-foot tube to get more powder into lesser calibres and had bugger-all improvement. Perhaps a tutorial into use of such tubes would help The Mission | |||
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Thanks for the reminder RIP. Most of the time I record temps, but for some unknown reason it was not done. But the date was Sept. 15/09, so I'd expect the ambient temperature to have been normal for the area at about 67 to 72*F. For THE MISSION! Bob www.bigbores.ca "Let every created thing give praise to the LORD, for he issued his command, and they came into being" - King David, Psalm 148 (NLT) | |||
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Regarding some other details: Sept/09 was a long time ago, so I don't recall my full rationale regarding details. However, these notes were made before the fact: Knowing that WW 748 was a relatively "slow" powder compared to the other ball powders employed, I loaded it to slight compression whereas H335 and AA2460 (ball powders) were loaded to max volume; i.e. 100%. These stick powders: Varget and IMR 4064 were loaded to 100% without compression. (That's where the word "normal" came from -- as in how most makers of manuals have operated in the past re: the .458 Win Mag.) IMR 4320 was not "max" in volume, having slightly smaller granules. After the fact (of shooting these loads), these brief notes were added to the MV results: Observations of extraction and primers: 748 - mild H335 - mild AA-2460 - mild 4320 - normal Varget - normal 4064 - mild As a further note of interest: I fired one of the 350 TSX loads on the same day = 2745 fps (instrumental) not corrected to MV. Bob www.bigbores.ca "Let every created thing give praise to the LORD, for he issued his command, and they came into being" - King David, Psalm 148 (NLT) | |||
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Perhaps at the risk of "overkill", I'll make mention that many years ago (like about thirty) I read an article in HANDLOADER (?) that gave an in-depth review of tests done on WW 748 that proved it was much slower than claimed in manuals. The author (don't recall his name) was very surprised at the results. But it made a lasting impression to my thinking because it confirmed my personal experience using that powder. Of course, the rate of burn isn't conditioned only by coatings, ingredients, shape or size -- we all should know that -- but ALSO by the cartridge it's used in and at what psi. In the .458 and .45-70, I've found it too slow -- can't get enough in those cases for a good burn and optimum pressure -- even though WLRM primers were used. Bob www.bigbores.ca "Let every created thing give praise to the LORD, for he issued his command, and they came into being" - King David, Psalm 148 (NLT) | |||
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Nuts! The Sightron 2.5x32mm is too short to fit on Bobbarrella using CZ rings. It is also an older SI series and the catalog says ExacTrack started with SII. But the Burris 2.5x "Fullfield" is plenty long enough to fit a CZ 550 Magnum with CZ rings.  Rip ... | |||
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Get a 26" long aluminum arrow shaft and attach a fitting at each end. Any plastic or aluminum fittings may be used. MTM/CaseGard ad below:  Secure a funnel to the top fitting with something as simple as Scotch tape.  Then I reach up with my right hand to dump the weighed charge into the funnel:  Simultaneously I hold the empty brass case snug against the lower fitting at the other end of the drop tube, over a little trash basket in case I spill:  You must have two hands on normal length arms and be able to walk and chew gum simultaneously to be able to use this equipment effectively. For scale, the wolf calendar is 12" wide, 24" long, opened and hanging. I have a plywood box and trash basket beside the table where I weigh powder charges. Convenient to just stick the drop tube there with duct tape. Tapping the case lightly a few times after drop tube does not hurt the settling of the powder. All of this does not do much. But it might allow adding a couple of grains of powder without compression. If you use hBN you may want to do that to get pressures back up to "normal" by adding about 2% more powder. Rip ... | |||
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Nope; ( I'll try to get my point across without going into a 2 page cuss fit) The Burris Fullfield 2.5 power scope is probably the WORST PIECE OF (fill in your own verbiage) ever made !!!! I have one that ha been back to the factory 4 , yes that's FOUR times and it is currently broken again. You will Repent if you put that total refuse on a good rifle like a 458. I never knew so many different things could go wrong with a scope and have wasted. Over a hundred rounds of 374, 416 Taylor and 458 Winchester ammo trying to sight it in and then re sight it in time and time again. You just can't imagine how horrible a piece of ---- ect it is. I think my blood pressure has gone up to dangerous levels just typing this and remembering it ! Take that off your rifle immediately and run over it several timed with a D8 or larger Cat Dozer. Or set it up on a target stand aimed straight at you and Carlos Hancock it !! Something . Phil Shoemaker : "I went to a .30-06 on a fine old Mauser action. That worked successfully for a few years until a wounded, vindictive brown bear taught me that precise bullet placement is not always possible in thick alders, at spitting distances and when time is measured in split seconds. Lucky to come out of that lesson alive, I decided to look for a more suitable rifle." | |||
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Thanks RIP, I wonder if my lack of the aluminium centrepiece might be to blame. I just joined some fat straws together and friction/static may have taken a toll.Cold Trigger Finger, did any of your problems with the Burris scope involve a rattling inside? PS: I like your username. Even as a kid in sunny Australia it was sometimes so cold I could hardly insert another round into my single-shot .22. | |||
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Yes ; but the rattle was the bits of crosshairs that were shattered and in a pile in the scope. Now the scope is stuck. So it won't adjust to the left. At 30 feet ish , the bullet impact was about 14" to the left. And it won't adjust any more. Phil Shoemaker : "I went to a .30-06 on a fine old Mauser action. That worked successfully for a few years until a wounded, vindictive brown bear taught me that precise bullet placement is not always possible in thick alders, at spitting distances and when time is measured in split seconds. Lucky to come out of that lesson alive, I decided to look for a more suitable rifle." | |||
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RIP, I remember an old article of Ross Seyfried when he rested the case on a vibratory case tumbler to help settle the powder in the case. | |||
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That's a good argument for laminated, etched reticles reticles, CTF. I don't have one of those tumblers, RIP, but must ask my wife if we have anything else that might work, a blender, perhaps | |||
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By all means, use a vibrator of any kind to pleasure your charged cases. Whatever works for you. I will not get the Burris 2.5x Fullfield fixed if I break it. I will dissect it. Rip ... | |||
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 Sightron SIII 1-7x24mm Illuminated German-4A:  This scope is a bit fat, long, heavy, and illuminated, but otherwise perfect for the .458 WIN. Rip ... | |||
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 This Sightron scope is optically superior to the Burris 2.5x20mm Fullfield.  Eye Relief is 4.8" on 1X. FOV is 91.9 feet at 100 yards, on 1X. Good field-blending, shoot with both eyes open. Controls on illuminated reticle are simple, functional, 4 buttons: One button is on-off. One button selects either red or green dot illumination. One button increases brightness of dot. One button decreases brightness of dot.  Rip ... | |||
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If I may stick my neck out again, I'll add these bits: Most manuals mention that its risky business to use "slow" powders, intended for magnum cartridges, at a lesser charge than recommended, even in the .458 Win. But, also, that is particularly so with ball powders. Appropriate ball powders work best at 100% filling or nearly so. In the case of seating bullets long, which creates more volume and air space, its quite normal to fill that space with powder, in particular if it's ball type. It's a dangerous practice to use a ball powder as a "download". Moreover, in the case of certain "stick" powders, some work best when compressed. By "best" is meant most consistent in MV and potential accuracy. At our range, two years ago, a fellow hunter-shooter was using handloads in his .416 Rigby for practice prior to a safari in Africa. He downloaded magnum powder for reduced recoil in shooting 400s. The gun blew up on him and he lost a thumb. Ironically, I wasn't there that day (it was my usual day to be there), and he was using the bench next to where I would have been! There was a hole through the rafter over where I might have been, where a piece of the action went clean through it! I'm fully aware of the potential dangers in loading our own! Yet in about forty years of handloading, I've never busted a gun nor locked up an action that had to be opened with a mallet. However that may come across, I'm really a very cautious guy. Bob www.bigbores.ca "Let every created thing give praise to the LORD, for he issued his command, and they came into being" - King David, Psalm 148 (NLT) | |||
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By "downloads", I'm referring to reduced loads of course. Bob www.bigbores.ca "Let every created thing give praise to the LORD, for he issued his command, and they came into being" - King David, Psalm 148 (NLT) | |||
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I would like to claim the same, except I started handloading only 37 years ago, with a Lee "hammer&woodblock" kit for the .44 RemMag handgun, S&W M29 with 6.5" barrel, gloss blue and checkered walnut grips. Yes, I was in my Dirty Harry phase then. Dirty Harry flamed my interest in the .458 WIN before Capstick fanned the fire. Inspector Callahan used the .458 WIN with "African" open sights as a counter-sniper rifle, for rooftop, urban shooting at night, in the first DIRTY HARRY movie. That cinched it for me and the .458 WIN.  John Hunter books in a grade school library probably sparked my first interest in "big bore" rifles. The .458 WIN M70 was the best alternative to a .500 NE double rifle back then. Still is. Rip ... | |||
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The perfect Counter-Sniper Urban Night-Fire Rifle aka the CUNR, the cunning CUNR, or just "Cunner" for short. This development will be hailed as far more important than the Scout Rifle concept of Jeff Cooper. I present Bobbarrella Shilen-CZ, the first CUNR:  The muzzle brake helps with prolonging the service life of the illuminated reticle on the scope. It might also help diminish the muzzle flash in the direction of target, protecting the Cunner Gunner from return fire by terrorists such as Scorpio Killers. The 25" barrel length is also helpful with reducing the give-away of muzzle flash, when shooting from one rooftop to another. The power range of 1X to 7X is ideal for all situations, carried on 1X until engagement, just in case a whack-a-mole pops up in a charge. Of course the CUNR is ideal for general safari use. "One planet, one rifle." Rip ... | |||
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I started with one of those original Lee kits as well, only in .30-06. The second was for a single shot .22 Hornet. Bob www.bigbores.ca "Let every created thing give praise to the LORD, for he issued his command, and they came into being" - King David, Psalm 148 (NLT) | |||
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So you were more of a "Dudley Do Right" type than A "Dirty Harry" type, eh? Well, I can understand that, my first bolt action rifle was a Ruger M77 "Round Top" in .30-06, restocked in fiberglass after its while in walnut. It is another case of "barely made it to a perfect fit with the Nikon SlugHunter scope":  Traded in my Marlin .30-30 lever action for that. The magazine cover is aluminum, not the whole floorplate, on this 2-piece bottom metal. The trigger guard is of steel, a replacement part meant for the Ruger M77 .458 Win.Mag. tang-safety model. You could buy them to replace the broken aluminum ones on other chamberings. So, even my favorite .30-06 has a little bit of .458 WIN in it:  I think I was puttering around in the garage doing this replacement of my scarred walnut in August 1988, when I heard Rush Limbaugh's radio talk show for the first time.  I was stuck in Tallahassee, dreaming of getting back to Alaska ... If only Dirty Harry had a CUNR like Bobbarrella ... the mind boggles at the possibilities for movie action ...   Rip ... | |||
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Seriously, The KDF muzzle brake makes the recoil of .458 WIN LongCOL Bobbarrella feel (to me) like that of the lightweight .30-06 above, with standard factory loads. Hopefully the Sightron scope thinks so too, and happily continues to be fully functional. Once again a 180-grain .308-caliber bullet with BC of about 0.37 can be used to match the .458 WIN LongCOL as trajectory trainer. Use a .30-06 and find an accurate, full-case, slow-powder load for reducing velocity to 2450 fps MV. That will match Bobbarrella with 450-grain TSX at 2450 fps MV. However this time the paired rifles will both have olive green stocks. Cute! More importantly an 8-pound, scoped .30-06 sixshooter and a 10-pound-scoped .458 WIN sixshooter will kick similarly. I have gone over to the dark side, the loud side, the muzzle brake side. May The Force be less on my retinae. My first bolt action rifle is thus paired with my latest bolt action experiment. I cannot improve on this pair. No way. Gonna have to carry on with single shots, double rifles, and semi-automatics now, just for kicks. Of course minor improvements on other rifles are still needed, such as with an existing .458 Win.Mag. Winchester M70 Super Grade Safari Rifle. Its 3.4" magazine box could be simply converted to 3.6" box length, ejector shortened, and the barreled action, gold inlay and all, dropped into a Bell & Carlson stock to protect the wood ... Better than any old .458 Lott: The .458 WIN LongCOL. (trumpet fanfare here) Rip ... | |||
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Muzzle brakes make accurate shooting easier by reducing recoil. Brakes can be hard on scopes unless the scope is rated for both positive and negative G forces. _____________________________________________________ A 9mm may expand to a larger diameter, but a 45 ain't going to shrink Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened. - Winston Churchill | |||
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Mike, This is great. We are now hashing out the muzzle brake on this the "Everything Thread." For THE MISSION!
Wouldn't that be about the sort of brake with rearward-directed ports to produce -G partially counteracting the +G of recoil? Not just any brake is going to produce a vector opposite from the direction of primary recoil. Forget BB guns and air rifles that need -G tolerant scopes. Every "internal combustion" adiabatic heat engine rifle's scope gets accelerated rearward (call that +G) and then decelerated against the shoulder (-G). Porting gas at 90-degrees to bore in a 360-degree circle can only reduce the stresses on the scope, both +G and -G, it would seem to me.  Rip ... | |||
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The brake decelerates faster that why felt recoil is Less. I’ve been shooting brakes for years but I have scopes rated for both positive and negative Gs. I shoot @ 338 Laups that sends a 300 grain SMK 2790 FPS that kicks like a 22-250. H _____________________________________________________ A 9mm may expand to a larger diameter, but a 45 ain't going to shrink Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened. - Winston Churchill | |||
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I have over a hundred scopes on hand and never read a G-rating on any of them in all the literature that came with them, from Schmidt & Bender to Beeman Brand on my BB gun.  Rip ... | |||
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I think cutting up old scopes is a great idea, RIP. We can look at the dimensions of rifle actions, their lugs and gas protection, evaluate their feeding and groups - but we have little choice but to trust scope makers' assurances of design and shockproofness. Only by pulling scopes apart and looking closely at design drawings will we have any idea of what's going on inside. I must look around here to see what else I can cut up. | |||
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sambarman338, Forget the G-Spot. Have you ever heard of "G-Rating" scopes for plus-G versus minus-G levels allowed? I don't recall reading about it in your book, or any other book ... I thought you would like the idea of dissecting a scope, any scope. Rip ... | |||
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Looks good. Better to mount scopes more forward on heavy kickers like as shown on my .458 Lott to prevent the possibility of getting scoped.  | |||
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Yep, what you have done is the way I like it too, whenever possible: Ocular end of scope in line with the rear of the trigger guard, or close as possible. With the behemoth Sightron I am "close as possible" as shown, with standard 30mm CZ-OEM rings. Luckily it will only be used with a muzzle brake, and then it kicks like a .22-250 with 350-grain TSX at 2800 fps, or like a .30-06 with 450-grain TSX at 2450 fps. Rip ... | |||
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Sorry RIP, my knowledge of the G-spot is also deficient, esp. in regard to scopes. Could you explain that one for the benefit of this innocent? I have heard that Delta scopes are subjected to tremendous forces, supposedly equivalent to about 70 times the recoil from a 458 or some such and, from an acquaintance, that they can take a lot of punishment on actual rifles. For all that, image-movement and rubber eyepieces have left them with more tunnel vision than looking through a toilet roll, so my argument doesn't just end with recoil resistance. | |||
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Time for some research. Rip ... | |||
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Alas, this is like one of those "the emperor has no clothes" moments. To mount that Sightron SIII "Long Tom" further forward, I need a Seyfried-Schtick Rear Picatinny, that schticks forward, because of the long ocular bell plus the variable power-change ring that take up space. For some other short-mounting-length scopes I need a Reverse-Seyfried-Schtick Front Picatinny, that schticks backward over the ejection port. So what I really need, to accommodate all the scopes I want to use, is a full-length, one-piece Picatinny shaped on the ends for clearance with low rings, or a 2-piece Picatinny that almost meets in the middle, with room for a thumb to pass between. A Seyfried-Double-Schtick 2-piece set up that schticks forward and schticks backward over the top of the rifle. Rip ... | |||
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RIP, I learned about G force rating in a conversation with VP of Nightforce _____________________________________________________ A 9mm may expand to a larger diameter, but a 45 ain't going to shrink Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened. - Winston Churchill | |||
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Any thought given to iron sights and a QD mount? Always liked the simplicity and reliability of iron sights. My proficiency with them isn't too bad out to 75 meters and could be improved with more practice plus beyond. Some areas where I hunt don't really require a scope and I would rather do without one. I've been in situations where I had to track in timber and removed the scopes from my Rugers for better field of view and quicker sight acquisition. The Ruger integral mount design is set up for quick scope removal. Pretty close to being zeroed when re-attached.      | |||
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4sixteen, Thanks for the eye-candy, for THE MISSION. I am saving my last Wisner copy of the M70 African rear sight, resisting the temptation to put it on Bobbarrella, like Alderella's treatment. Jim Wisner only had two left when I got them. Since Weatherby quit putting them on their DGR, I think he quit making them, though he could start up again. Sometimes a guy just wants a rifle with no hardware add-ons cluttering the barrel. Scope use backed up by instinctive shooting at close range. If you have to shoot fast at spitting distance, you just point and shoot, or spit, "irregardless" of open sights. Saeed-style. Rip ... | |||
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4sixteen has goaded me into sliding the Sightron behemoth forward a wee bit by using a Double-Seyfried-Schtick 2-piece base. I used a drill press and a half-dozen carbide bits with some turbine oil to fit the holes on the rear base. Then I used some files and a hacksaw, and my hands and eyeballs. Result was a Bubba Gunwerkes, bespoke, hand-fitted rear base, Seyfried-Schtick style. It is 2-1/2 inches long, and has support/stiffening struts under the overhang. Those struts will abut the rear bridge via J-B Weld backfilling of daylight space:  The front base above is a Reverse-Seyfried-Schtick base. It has a recoil stop on the bottom that THE GUNSMITH fashioned, expertly, so that it actually contacts the front receiver ring as a recoil stop. There is still some room for J-B Weld forward fill, so as to have no daylight between the base and the rifle. It was formerly part of the one-piece Picatinny, but I used a hacksaw to cut off the forward 2-3/8" of that. Thus, the Double-Seyfried-Schtick (DSS) 2-Piece scope base is born. There is a 1-1/4" gap between the bases, and a thumb fits there nicely. The "thumbgap" is for aid in loading those LongCOL and SAAMI .458 WIN cartridges, six of them, into the magazine. I still have some polishing and de-burring to do, and maybe some more filing on the leading and trailing edges, if they interfere with a Nikon SlugHunter in low rings. Always a good option on a .458 WIN. I am thinking of using this base exclusively on Bobbarrella, no need for CZ rings. Low Burris rings and this base will mount the scope 0.005" lower than the OEM CZ "standard" rings.  Rip ... | |||
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