The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Big Bores .505 Gibbs CIP brass specifications: The TruthGo | New | Find | Notify | Tools | Reply | |
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After much study I have concluded that the .505 Gibbs as shown in the A-Square manual is the only correct published drawing that I have found yet, showing every dimension and the shoulder angle correctly. Again the book by Art Alphin is tops. I trust his pressure data more than any other source. It is reassuring to have such a good book. No other load manual is as good for the big bores. I would like to enlist the aid of this excellent forum in putting this to rest. Are the Clymer reamers all screwed up? Is Ken Howell leading us astray in his book _Designing and Forming Custom Cartridges_? Is Art Alphin the only one who got it right, even though the company under new management still can't make brass properly? Where is another CIP cartridge drawing with all the right specifications? I'll be googling.  | ||
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ALF, Thanks for the pointer. I see now that the 2 versions that Dr. Howell shows are compatible if you allow a variance of shoulder angle with the minimum in version 1 ("Birmingham Proof House") being 37.6 degrees, and the "CIP maximums," version 2, being 45 degrees. The CIP Maximum head and rim diameter is 0.6402" and the Birmingham Proof House spec is 0.6400", etc. I get it! That clears it up for me.  The Ken Howell drawing of the Birmingham Proof House specs doesn't include any shoulder angle specification. However, I see that it is the same in length from base to shoulder and length from base to shoulder/neck juncture as the A-Square drawing. Using the value of the tangent for the 37.6 degree shoulder, I see that A-Square and Ken Howell agree on the specs. That does it for me. The Birmingham Proof House specs are IT. THE TRUTH. WRITTEN IN STONE. Much appreciated. If you ever get info from that CD of CIP specs it would be a gold mine. Let me know if I may be of assistance to you in anyway.  | |||
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So are there .505s out there which fail to comply with the Birmingham Proof House specs? | |||
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Just a quick question. Didn't you note that the new Jamison .505 Gibbs brass conforms to the same PSI specs as the .408 CheyTac brass???  I thought you noted this while you toured his plant. "Jest Ckekin'."  "They who would give up an essential Liberty for Temporary Security, deserves neither Liberty or Security." ---Benjamin Franklin "SIC SEMPER TYRANNUS" | |||
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If you look at the Clymer reamer specs (versions one and two offerred simultaneously) you would have to conclude someone has their head up their arse, or there are some typos. Version one has a 25 degree shoulder angle. Version two has a 37.75 degree shoulder angle. Version one has a base-to-shoulder dimension of 2.2230" Version two has 2.2960". Donnelly says: 18.84 degrees and 2.4600" Correct answers according to Birmingham and A-Square: shoulder angle = 37.6 degrees base-to-shoulder = 2.4580" Must be only an "American" problem like with the .404 Jeffery.  | |||
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Woodsracer, That is true. The brass by Jamison will handle more pressure than the rifles can stand. That is always the "case" with good brass. The Jamison .408 and .505 brass have thick heads that can handle 70K PSI. With the Gibbs head size, given bolt thrust considerations, the CZ 550 Magnum and the Dakota 76 African and even the Prechtl and Granite Mountain Magnum Mausers must be held down to 55K PSI. If you want 70K PSI loads for the .408 Chey-Tac, then you need an action designed for the 50BMG with the boltface downsized and the locking lugs "full-sized." | |||
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The A-Square manual drawing is the correct one. Ken Howell's Birmingham Proof House drawing is correct too, but it left out the shoulder angle specification. The correct angle is indeed 37.6 degrees, or is that 37 degrees 34' 55" as another "CIP" spec'ed drawing I have purports? Oh nothing Grandma Bibi, just pounding primers with a hammer ... | |||
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With many of the cartridge case designed for big bore rifles there are often conflicting numbers. 500 Jeffery/500 Shculler 404 Jeffery. 505 Gibbs. ON and ON. The fact is that very often the mistakes were made and passed on so many years ago .The computer and its infinite memory is just a recent phenomon. On my 404 Jeffery, the reamer I use is my own therefore, ALL of my rifles are the same configuration and all of the brass will fit any of the rifles. I don't tend to run my Jeffery as hot as some do. When I had my 505 Gibbs, I bought some once fired brass from a AR member and none of it would work until I lowered my shell holder height .010 and did a hard FL resize on them. When making my current 500 Jeffery, I had to specify either the Schuller or Jeffery configuration. ON a side note, I have an original 416 Rigby by Rigby and the chamber would not allow for chambering any of the current crop of 416 Rigby ammo. NONE of it. I sent the rifle to Sterling Davenport who was one of the original few authorized to work on Rigby rifles in the USA. He had to recut the chamber to a more "Modern" chamber specification. I don't know who is right on this arguement. Was my chamber too small from a reamer used too many times or had the specifications of the reamer changed over time? square shooter | |||
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Oh Lordy! At least with a straight walled rimmed case there are fewer dimensions to screw up. Let's stick to .500 NE, .577 NE and .600 NE.  | |||
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"They who would give up an essential Liberty for Temporary Security, deserves neither Liberty or Security." ---Benjamin Franklin "SIC SEMPER TYRANNUS" | |||
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After building my 505 and having problems with the bullets sticking in the throats I compared the reamer drawings from Clymer, JGS and Manson. They are all different. I wonder if there really is a standard dimension on this old cartridge. My reamer was purchased from JGS but they will acknowledge no problem. My solution was to have them make up a throater reamer. Now I fit the lead to a loaded cartridge. I also ran into problems with Woodleigh bullets changing shape. With my corrected throat it was working perfectly, then a new lot of bullets started sticking again. That was with the bullets seated to the crimp groove. A little deeper with the throater reamer fixed that. I suspect many rifles will need this alteration depending on the bullets being used. As far as pressures go, these babies’s don’t need that much. If anyone is loading their 505 to over 50,000 PSI then he is one tough son of a gun. Marshall Jones | |||
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Aye, the A-Square Manual cartridge drawing and specifications are to the correct standards of the Birmingham Proof House, as is Ken Howell's Book drawing if you insert the omitted 37.6 degree shoulder angle (or hemi-angle or semi-angle or whatever you want to call it). Plain and simple as mud, now, to this American. woodsracer, The Granite Mountain action with the 0.750" bolt diameter is only 0.05" thicker than the CZ or Dakota, barely more than a millimeter. I don't think the locking lugs are much different, and it would surely be prudent to keep the pressures in that the same. | |||
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At least someone with a brain and a common sense. Pyzda | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Big Bores .505 Gibbs CIP brass specifications: The Truth
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