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Ultra Big Bore Rifles....................

Discussion in 'Big Bore Rifles' started by Michael458, Apr 1, 2019.

  1. Michael458

    Michael458 Active Member

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    Ultra Big Bore's by B&M Definition is any caliber over .510 caliber.

    We have some experience here with Ultra Bores, however, we do not own any. Ultra Bores require very large, heavy, long, and cumbersome in my opinion platforms, or rifles. These are a long way from the short and handy DGR I prefer. Most folks have the "Mine is Bigger Than Yours" syndrome with these.

    The one exception to this rule is my good friend Sam Rose. Sam loves his double rifles, and his favorite double rifle is his 577 NE guns. These are big guns, and heavy, but Sam puts his to good effect, and we have done a lot with his various 577s here. 577 NE is actually .585 caliber.

    I have never been impressed at all with Ultra Bore performance in the field. In fact, I have watched and heard of more failures of Ultra Bores, on buffalo and Elephant than you can count. Actual performance in the field has been "dismal" at best......

    Until.................

    In the early days of our Bullet Research here, Sam brought one of his MIGHTY 577s down to do some testing. It was going to be a very interesting day. I had little to ZERO experience with Doubles, much less the mighty touted 577 NE.

    In those days Sam was still shooting the old Woodleigh Round Nose solids. Solids play a MAJOR role when hunting large Dangerous Game. Many of you probably don't know a lot about solids, and how or when they need to be applied. But here, we believe very very strongly in the use of solids for many areas of hunting, and not only for large dangerous game, such as buffalo or elephant, but in many areas Good, and "Properly" designed solids have a use in all sorts of game fields, that you may not have thought about.

    But in .585 caliber, good solids were not designed until very recently. Everyone just relied upon the very few that were available, mostly from Woodleigh being the old standby. And, as we learned, the major cause of the problems associated with many failures of solids in most all areas.

    Having already been working hard with solid technology, Sam was going to get an introduction to this. I had one Ultra Bore here at some point before Sam came down. It was a 600 OverKill, .620 caliber. Performance was dismal in that thing. Terminal Performance. I have two boxes for Terminal Performance Tests, both capable of being filled with 65 inches of Wet Print Material.

    Wet Print is NOT Animal tissue, nor is it trying to simulate Animal Tissue. It is a cheap, and consistent medium in which we can test various bullets, with everything being the same. We take extreme pains to make sure of this. What we do know, 100% fact, is that Bullet Behavior in this Wet Print test Medium is exactly the same, as bullet behavior in animal tissue. What you get in the test, is what you get in the field, of course one has to take into account "Bone" in animal tissue, that disturbs the process somewhat.

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    There are actually two of these boxes, and when we test properly designed big bore solids, both boxes have to be lined up back to back to catch some of these.......

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    Sam was concerned, but I assured him we would not need or require two boxes to catch the Round Nose .585 caliber solids. Just not going to happen..........

    As you see below, the big 750 gr Round Nose only went to 14 inches straight, before it took a turn hitting bottom of the box and scooting along to 36 inches max. Remember, ONLY STRAIGHT LINE PENETRATION counts with solids. If it veers off course, from the point it veers and turns, that is no longer VIABLE penetration....... You might as well MISS completely.

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    OMG This set Sam on Fire! Sam is extremely talented, has a Lathe and can do damn near anything. Sam was instrumental from this point on in our Solid Bullet Study, and our Endeavor to discover The Perfect Solid. In the end, We accomplished this, but it was many 1000s of rounds, 1000s of bullet fired and a tremendous effort that was put forth, and I am talking several sessions a week testing various designs.....

    Barnes at the time was headed in the right direction with their Flat Nose Designs, as you see here, a hell of a big difference in Straight Line Penetration.......

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    After much work, much testing of various Factors involved with Terminal Penetration of Solids, which include the following........




    Factors Involving Solid Straight Line Penetration & Depth of Penetration

    #1 Meplat Percentage of Caliber


    #2 Nose Profile


    #3 Construction & Material


    #4 Nose Projection


    #5 Radius Edge of Meplat


    Above Factors are in Bullet Design


    #6 Velocity


    #7 Barrel Twist Rate


    #8 Sectional Density

    The basic BBW #13 Solids were designed................

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    Other factors that we were working on, were Bearing Surface, this had a tremendous effect on Double Rifles in particular with "Barrel Strain"...... reducing bearing surface made these bullets perfectly safe to use in Double rifles, without having barrels separate. It also reduces pressures overall, allowing you to gain more with less pressure.

    We worked with two bands, one top, one bottom, and this 3 band version two top and one bottom. In the end, we settled for 3 bands at the top, with one at the bottom. This allowed more versatility in seating the bullet in different cases at different depths. 4 Band pressure and barrel strain was no more than 2-3 bands. But if you went above 4 bands you started increasing both. No, accuracy with these bullets has no bearing. They are hole for hole if you do your part........

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    And here, you see a difference in penetration, this is mostly because of the Larger Size Meplat........

    [​IMG]

    Sam was excited about his increased performance, and it was not long before he left for Africa with his 577 NE and some brand new bullets to test..... Sam was the first individual to use the New BBW#13 Solids on elephant and buffalo. When he left, I told him he was carrying the Most Effective 577 NE that had ever seen the African Continent. I was right....... He was extremely successful on both buffalo and elephant. The bullets had performed even better than we expected.

    Now the Ultra Bores had proper bullets............. we are seeing success now with 600 NE, 577 NE and the various 600 OverKills that are out there.........

    Below is a friend that used his 600 NE on elephant .................

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    Of course, with proper bullets.....

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    Sam still hunts with his 577 NE, but learning all we have from our test work, Sam took the weight down from 750 gr Solids and 700 gr Raptors, to 650 gr Solids and 600 Gr Raptors. Velocity can be increased, along with Terminal Performance with these in Double Rifles.

    Sam has used this for many a buffalo and several elephants.........

    [​IMG]

    Next up is the mighty 600 Overkill, here is a preview of this..............

    [​IMG]
     
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  2. Michael458

    Michael458 Active Member

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    One of the first big Ultra Bores brought in was by my pal Corbin Shell. He had picked up some sort of CZ thing, someone had built and it was a total POS--- Piece of use your imagination! This thing would not feed/function at all. Hell, you could not load a round down in the magazine, much less try to get it to feed one. The only way we could shoot was to remove the bolt, hand place a round under the extractor, then slowly put it back in the gun. It was awful. Corbin had loaded up several things he wanted to test, I will just run down the list with photos.........

    900 gr Woodleigh Softs at two velocities......

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    Cast bullet of some sort..........

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    And we probably did some other things with it as well that I don't have photos of. It was extremely "Un Impressive".................

    The fellow you see with the elephant in the prior post is a fine fellow, and he loves .620 caliber. He also had a 600 OverKill, this one built on a big Granite Mountain action. This gun would actually work, feed/function. He was extremely interested in our work with bullet design, this was BEFORE he used the bullets for the elephant above. So we developed some .620 caliber Solids and Raptors for the guys with Ultra Bores, but no gun. Our friend was kind enough to send his gun down for us to test with, and do a bit of load data as well....... We had a 900 gr Solid made, and Raptor from the solid came in at 825 grains... This is still what is out there today. Starting at 150 gr of WW 760 we ran the 900 to 1895 fps....... we ended at 170 gr WW 760 for 2161 fps, and that is Plenty. The rifle is big, it came in at or around 15 lbs with heavy 24 inch barrel. Below is a photo of the gun on top, compared to a 21 inch Win M70 in 500 MDM and a 18 inch Win M70 in 50 B&M.............The Winchesters look a bit "dainty" under this thing...........I consider the 500 MDM BIG.... LOL........

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    The boys were actually teasing me a bit about having a "500 caliber Rat Gun"...... Sam saw I was taking a beating over these bit 900 gr Solids, so Sam made me a REAL bullet, at a full 1 inch in diameter.......You see it all the way to the right of this photo. It was funny, and it weighed in at over 4000 grains..... HEH HEH....

    [​IMG]

    It really made those big 900s look like rat bullets.........HEH HEH.....

    The #13 Nose Profile is great for velocity. A lot of other Nose Profiles do not react to higher velocity well in some cases, not the #13, more velocity, more penetration, regardless of caliber.................

    [​IMG]

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    And very much the same results with the 825 gr Raptors........ ( Back then, they were called NonCons short for Non Conventional)

    [​IMG]

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    Now all this work, load data, and bullet tests, had to be done from the Bench. You can't do this sort of work properly if you don't. So that mean sitting down at the bench, tucking in tight and hard against the shoulder and shooting. Doing a few rounds was not all that tough, especially any that were less than 2000 fps, it was a heavy push, but tremendous muzzle flip. Rifle would come up, way way up......... The last morning of test work involved shooting I think 22-23 rounds from the bench, and I don't do a lot of complaining about recoil, but after this, I was really happy to send this beast back home.

    There are a few more Ultra Bores, I think there is a 550 Magnum, a fellow named Neil Shirley developed it. I know there are some CEB bullets for it, but not sure what else, it is not even a common Ultra Bore. When you get to Ultra Bores, bullet choices are few, but CEB took care of .585 and .620....... No doubt.

    Rifles are big. In my opinion too big for most things. I would not go to the field with a 600 OK. Too big, cumbersome, handles like a 15 lb musket. Too slow on recoil recovery for second shots..... Just nothing good about them, they are BIG BIG BIG........... Sam can handle his 577 NE very well, but he is shooting lighter bullets, and his gun also weighs in at 15 lbs....... I am not going to tote around something like that all day. I shortened my big 500 MDMs down to 19 inches, and 8.25 lbs, I think they are too big.... LOL......................... At least today, with these bullets, they are extremely more effective than they were.

    All this just to let some of you know there is something bigger than Big Bore............. Now I assume you are "Bored to Death"......... Pun Intended............. HEH
     
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  3. Catfish

    Catfish E Pluribus Mendacium Charter Member

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    9,335 ft-lb at the muzzle! Does your shooting bench have a seatbelt?
     
  4. Slacker

    Slacker Liquor and Whores...

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    Love these threads but just reading the words "900 gr solid" makes me flinch.
     
  5. Michael458

    Michael458 Active Member

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    HEH... Almost, its screwed and tied into the wall to keep it from moving............ I also throw a few bags of shot over the front end............ But ended up tying it into the wall to keep it in
    one spot.......
     
  6. Michael458

    Michael458 Active Member

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    Thanks...... But this will be all I have on the Ultra Bores..............
     
  7. Michael458

    Michael458 Active Member

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    Oh, and just FYI on this 600 OK, it can drive, it is capable of driving 900 gr bullets to 2400 fps I am told. I did not do that, I hit 2150 or so, and said to "self", "Self, that is enough"...........
     
  8. JimP42

    JimP42 Mostly harmless Benefactor Charter Life Member

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    Why? Because!

    Very cool story/history/info/science!