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Discussion Starter · #1 ·
Plan a build with Randy Selby in Wapiti WY. Remington 78 will get action truing/Douglas barrel/Remington classic stock. Deciding on barrel length 23-24 inches. Was gonna try something like a 375 Ruger necked down to 8mm, call it the 8mm Idaho, but decided on the Gibbs, Randy has done many Gibbs projects and will also do load development. RCBS dies on order, Hornady 35 Whelen brass in hand. I will get him this project hopefully very early in 2017. Does anyone shoot the 8mm Gibbs or have any date. Thanks and Hello forum.
 

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Discussion Starter · #2 ·
Shot some loads today. Fireformed cases are Hornady 35 Whelen. Loads is 185 gr PSPCL, powder H4350, CCI 200
60 gr avg 2550
61 gr avg 2615
62 gr avg 2660
63 gr avg 2720
64 gr avg 2780

No extraction issues or signs of pressure. 100 fps behind the 3200 Hawk according to the Hawk book. Will try little more, 3200 Hawk listed as 66.5 max. All loads measured with MagnetoSpeed V3 chronograph.
 

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Dodge, I think you could squeeze a little more out of her...say 2850fps. I would also try RL19 and maybe 17 too. powdr
 

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Discussion Starter · #4 ·
Powdr, I plan to work up to the published Hawk load of 66.5 and see. I had some case splitting issues due to my RCBS die scratching the case. That's fixed. I have some RL17 and H414 to try as well.
 

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150 ft/sec. steps

Powdr, I plan to work up to the published Hawk load of 66.5 and see. I had some case splitting issues due to my RCBS die scratching the case. That's fixed. I have some RL17 and H414 to try as well.
Kudos for starting with a real commercially chambered barrel. I used old stepped military ones and got Plus 150 fps. between stock 8mm Mauser, 8mm x 06G ( std ), and then my own Americanized Schuler wildcatted 8mm x 375 Ruger, made from 375 Ruger Basic brass.

The Big Dawg here is the Remington Big Eight. How closely will you come to this overbored commercially available cartridge? I felt if I had a commercial barrel, chambered for my Schuleresque wildcat, I'd come pretty close, using ten grains less powder. But I gotta find another left hand friendly rifle, to re-barrel, for my next go with this wildcat. I felt that just like with Layne Simpson's review of the 2005 Remington 8mm Mauser classic M-700, I too, lost three inches of barrel length, from my rifles' sloppy military throats.

F.W.I.W., the Speer 170 gr. spitzers were always designed to run at 50 KCUP pressures. Otherwise there are now four newbie 8mm bullets made to reload Rem. Big Eights. The Speer version is their 200 gr.
 

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Discussion Starter · #6 ·
At the range this morning, all factors the same.
64.5gr
2832
2850
2853
2823

65.0gr
2836
2842
2868
2846

65.5gr
2882
2867
2867
2883

66.0gr
2884
2891
2883
2881

66.5gr
2901
2906
2888
2920

No extraction issues. No split cases. Might need a bit faster powder. 4064 or 2520

Does this amount of H4350 need a magnum primer?
 

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I wouldn't think so, but you could try and see if it makes any difference.
 

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Dodge8mm, why not go online and locate the Powley Powder Computer program. Steves Pages has it, and so does an American page. IMR 4831 should come very close to your H 4350. But you cannot substitute it directly. What you can see, is if the quicker IMR powders will have any advantages. I used short cut IMR 4831, in both my standard 8mm x 06, and my larger wildcat 8mm Mag., I then tried only a few rounds of R-22, under 220 gr. Sierra Game Kings and a starting load gave 2630 fps, IIRC. The original, and slightly smaller 8mm x 68mm S Schulers, get 2900 fps, but they use special German bullets and powders. And I believe all of these fancy velocities were attained in commercial German barrels. But they are what the African Sportsmen hang their hats on. IMHO, neither my 8 x 06, nor your 8mm Gibbs, has enough capacity in a standard length box magazine rifle to handle 220 gr. Game Kings, anywhere near 2900 fps. If I put my 8mm x O6 into a full length Savage rifle, and seated out these longish slugs, I think I would come close to your 8mm Gibbs, when it's used in a standard length, 3.4" magazine. The joker is that modern Schulers are still using the original 1935, 1 in 11 twist. Herr Schuler wanted to use the military 1 in 9.5" twist, but it was too quick for the bullets available, between the wars. So it's stayed a hot rodded, express cartridge, for all these years.
Chambering the Schuler into the quicker military twist commercial barrel, means starting from scratch to make safe reloads. Only now, using the four available Remington Big Eight bullets, will keep things together.
My next go, will be, using a 1 in 10 American commercial barrel, when I can score a full length magazine, left hand, donor rifle.
 

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Discussion Starter · #9 ·
Carpooler, I have used it, don't know either how to read it or input to it. Brings up two powders and ranges. Maybe some training is due on my part. I put in the measurements of the components, and it give 58 grains of 4831 or 4350 for 2600 fps. What can I change for pressure to run 60,000 and give me weight appropriate powder?
 

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Discussion Starter · #10 ·
More shooting today. Same setup as before except A-2520 powder
55.0
2788
2749
2710
2750

55.5
2782
2757
2767
2787

56.0
2738
2843
2803
2730

56.5
2789
2824
2825
2824

57.0
2869
2843
2814
2826

Seemed a bit inconsistent. Will try a bit more powder, seemed good on pressure signs, Also want to try IMR-4064.
 

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Discussion Starter · #11 ·
More shooting today. Same setup except CCI-250 primers (ran out of standard) IMR-4064
54.0
2625
2571
2566
2575

54.5
2616
2658
2620
2636

55.0
2643
2683
2679
2690

55.5
2706
2703
2665
2691

56.0
2720
2703
2732
2710

Will go up more on the IMR-4064
 

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Discussion Starter · #12 ·
Same setup CCI-200 with BL-C(2)
60.0
2727
2776
2765
2777

60.5
2784
2799
2840
2850

61.0
2830
2802
2818
2787

61.5
2815
2815
2863
2842

62.0
2880
2849
2858
2847

Will go up a bit more on this powder as well.
 

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Dodge8MM, I ran the 8 x 64S on the Powley Program, and they suggest 4831 or 4350, IMR, only. Be careful as 50,000 CUP equals 59,000 PSI. I stuck with the stock 8 x 06, since I always planned to make my own wildcat. Then I picked up a second, identical BRNO, with the same 29 inch barrel. I really doubt that you can pick up + 150 fps, over an 8 x 06, with just the slight Gibbs's advantages.


I'm guessing that Rocky was running tests at around 70,000 C.U.P. which is a No, No. Stick to the Powley's 50,000 C.U.P. levels, and work up from these, "Starting Loads", of around 46,000 C.U.P. Remember that the older Speer 170 gr. spitzers are equal to the 165 grs. in the smaller thirty calibers. You kinda crossed the Rubicon, with the Gibb's chambering. Otherwise, you may have used a 8mm x 338 Win. Mag. My wildcat is only a bit larger, and I think both of these, will nip at the heels of the Remmie Big Eight, which is overbore, and by using ten grains less powder. Those Big Eights come with 26 inch long barrels, in full length magnum actions. This boomer is a 300 Weatherby, without the dual radius shoulders.


So the 7mm STW, the Rem. Big Eight, and the Rem. 416, ( 10.6mm ), all use the same design, and lengths. Except that they also are only head spaced on their respective belts.
 

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Discussion Starter · #14 ·
Carpooler, I notice some differences in 8mm-06 load data, Nosler loads to a lower pressure than Sierra. I am essentially extrapolating from the Sierra manual. I also know my cases hold 76 grains of water. So I also use 338-06 and 338 Scovill data to start as well, keeping in mind that the larger 338 is a bit different due to surface area.
 

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Discussion Starter · #15 ·
Powley Compter shows 4350 as powder but leaning toward 4320, so a bit faster than the 4350. Trying to use close to dimension load data that is out there. 338-06, 338 Scovill, 8mm-06.
 

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dodge8mm No, the newer powders are a little bit quicker, even in the canister grades. So start where Powley says, and then work up a half grain at a time. Powley's computer only works with the old IMR powders, tit for tat. Every grain had the same energy from it's nitrocellulose base. Smaller grains burned faster. With all new, and foreign factories, and deterrent coatings, this may not be the case anymore. And IMR 4831 will be quite different from H-4831. All of the old WWII 4831 is long gone. I purchased some of the last of it in Brown Paper Bags, filled down at Lolo Sporting Goods, in Lewiston. It was losing it's energy rapidly, so I shot it up rapidly.


Don't despair, some of these moderate, starting loads, may be the most accurate in your particular wildcat rifle. The online Nosler Ballistic reloading table pages, notes this with the rifles that they used to test with. Their highest velocities only came with the best accuracy, with about one in five cases. Half of the most accurate loads came somewhere in the middle of their loading data.


H - 4895, and NOT IMR 4895, has reloading data for most of these rounds, but not including for your wildcat's. But this is the slowest powder where Hodgdon's publishes reduced loads for "some" cartridges. If they publish a load, cartridge, powder, and bullet weight, you can reduce it per their directions, around 40%.


I'm not suggesting you try this, only that you won't have to watch out nearly as close to airspace over the powder in your 8mm Gibbs. With the other slower powders, you don't want a full ten percent. In some cases the safe limits are down to between 3 or 4 grains of powder. And fifty year old loading data for the wildcatted Gibbs rifles, are not safe to use anymore, due to the above mentioned powder variances.


I didn't even recognize most of the powders you've tested over the chrono. But I have powder with $5/lb. stickers still on the flat metal cans.
 

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Discussion Starter · #17 ·
My first go round with the H4350 was out of the Hawk manual. It listed a 3200 (8mm) Hawk with 73gr water capacity, I measure my Hornady brass at 76 when fireformed. My load was below what a published manual said as far as velocity. I surmise that to be due to more capacity in the Gibbs. I may try a bit more with the H4350. I liked the H414 and R17 I tried, but cases split at the previously mentioned scratch from the dies.
 

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Discussion Starter · #18 ·
I had Barnes run some data with 180 TSX and R17 and H414, 2850 fps, with I believe ~58gr of either. Id have to relook at it to verify. Might be a place to start too.
 

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Are you just trying to do something with velocity instead of accuracy? How do these loads SHOOT?
 

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Discussion Starter · #20 ·
I've have just been seeing what kind of velocity I can get so far. Pretty confident this rifle will shoot almost anything well.
 
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