aw poop! It has rained most of the day. So now we reschedule for 9am tomorrow. We will hope for some sunshine.

Rich
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quote:

Originally posted by Idaho Sharpshooter:
aw poop! It has rained most of the day. So now we reschedule for 9am tomorrow. We will hope for some sunshine.

Rich
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Rich,
As they say over here ... "harden the f*@4k up" man. It's only rain!! Jeez ... they must breed 'em soft in the States
Cheers...
Con
PS: Feel free to send any rain you can this way ... neigbour was forced to sell the dairy herd yesterday ... its going to be another bad summer

It ain't a problem shooting in the rain, it's just that the fricking chronograph won't read the velocity...and I ain't gonna repeat myself. The indoor range said no, make that "H-E-L-L NO!!!" when I asked them if I could shoot there. I'm short of bullets for a couple more weeks, so no wastage planned for. Personally, I'd shoot it just for the sensory input, but there are dozens of AR members who need the entertainment seeing me shoot.
Being an Icon here ain't all biscuits and gravy mate!

Rich
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RICH

What is the diameter of the lead bullets from the mould you got from NEI?

RNS,

the 550 Gibbs bullet weighs 881 grains, is 1.48" long, and mikes .552".

the 577 BME bullet weighs 1010 grains (!), is 1.510" long, and mikes .582".

Again people, the credit has to go to Neal here, his sending me a couple cases to speculate is responsible for all of this.

Rich
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RELIGIOUS EXPERIENCE 12:17PM at Sand Hollow, Idaho!

I loaded two rounds each with VVoy N160, N165, and N170 with the 715gr cast bullets to start testing. They had worked well in two different 505 Gibbs with 650gr GC cast bullets, so it looked like the place to start.

125gr N170.......1683fps This may be too slow a powder for the light(er) bullet
125gr N165.......1915fps This got my attention, .001" case head expansion
125gr N160.......2156fps This is a low pressure, like less than .002" case head expansion from FL sized load as well.

We have a winner here.

I'm going to shoot a dozen to fifteen more rounds tomorrow, weather permitting. My, oh my!


Rich
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Addendum:

the 2156fps load generates:
7,382fp ME.
Taylor KO Value is 122
Recoil is 122 ft/lbs at 27fps recoil velocity
This in a ten and one-half pound rifle.

Recoil left no red mark, or soreness, due to being smart enough to wear the McCoy Recoil Shield pad. I tried one round afterwards of the N170 load, and it smacked me pretty good. The Recoil Shield...I could have fired a dozen rounds of the N160 load from the bench at one minute intervals comfortably. This is one product I highly recommend for anybody shooting anything over a 375H&H!!

With the Recoil Shield I think 2400fps is reachable.

Wow!!!


Rich
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Congrats Rich...
Waiting on the pics

If the mythical MRC PH comes out (I'm in line for 2 set up for 505 Gibbs) I think I'll have to commit one to the 550 Gibbs, Rich. I have a big bag of Neal's 505 basic brass, too!

tiggertate,

this thing is the second coming. I think I can duplicate the T-Rex ME levels with the 715gr bullet weight.

Rich
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T-Rex levels, my lord, I know you're awful glad you've got that recoil shield!!

quote:

Originally posted by Idaho Sharpshooter:
tiggertate,

this thing is the second coming. I think I can duplicate the T-Rex ME levels with the 715gr bullet weight.

Rich
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In that case the Bubbas will set up the Texas Bubba version of Saeed's reloading room and invite the hapless, helpless and arrogant working/visiting Houston to shoot a little 'ole Idaho rifle and videotape the carnage. Imitation is the sincerest form of flattery!

quote:

Originally posted by tiggertate:

quote:

Originally posted by Idaho Sharpshooter:
tiggertate,

this thing is the second coming. I think I can duplicate the T-Rex ME levels with the 715gr bullet weight.

Rich
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Knowledge not shared is knowledge lost...

In that case the Bubbas will set up the Texas Bubba version of Saeed's reloading room and invite the hapless, helpless and arrogant working/visiting Houston to shoot a little 'ole Idaho rifle and videotape the carnage. Imitation is the sincerest form of flattery!

If this turns out like I think, I'm going to sell my CZ 505 Gibbs. No need for a puny little thing like that crowding my gun cabinet!

Rich
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quote:

Originally posted by Idaho Sharpshooter:
If this turns out like I think, I'm going to sell my CZ 505 Gibbs. No need for a puny little thing like that crowding my gun cabinet!

Rich
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Do you have a photo of this monster you're testing?

Per Rich;


550 Gibbs magnum 710gr cast bullet, NEI 881gr cast, 480 Ruger loaded round, for scale, 1010gr NEI 577 bullet, and 577 case.

Ok I was talking about the rifle not the round but what is all that stuff? Left is a 505 Gibbs blown out to 550? Right is a Weatherby basic?

Macifej,
That is a 577 BME, not a Weatherby basic. A belt swaged onto a .505 Gibbs basic cylindrical case, necked to .585-caliber. How do you like it?

quote:

Originally posted by Idaho Sharpshooter:
tiggertate,

this thing is the second coming. I think I can duplicate the T-Rex ME levels with the 715gr bullet weight.

2473 fps with a 750-grainer in a 26" barrel at 52,600 CUP, just under 65,000 psi: 10,180 ft-lbs is the maximum T-Rex load.

Just how close do you dare to get to that?

What kind of rifle action do you have on that beast?

quote:

Originally posted by RIP:
Macifej,
That is a 577 BME, not a Weatherby basic. A belt swaged onto a .505 Gibbs basic cylindrical case, necked to .585-caliber. How do you like it?

I think you guys did a bang up job! Very clean job on the belt from what I can see. That's some serious horsepower in a standard rifle. I think Saeed and those guys built those UAE Rex Express rifles pretty heavy. Ya'll be careful of your cabezas with that thing. I once gave myself a nice concussion at the end of a load development session with a .460. Besides! If Ya'll gimpify youselves who's gonna field test the combat commander version of the 2-Bore I'm building?

And I am dying to see your 2 Bore Combat Commander. Beltfed?
Ought to be a big step up from this muzzle-braked 14-pound T.Rex:


Shooting Rich's 10.5 pound .550 Gibbs would make ME feel like this most likely:

Trivolver actually! Load Once! - Shoot Thrice!

Kidding of course! Having a little regulatory diversion with the man and fired a primary vendor but progress is continuing.

577 Tyrannosaur
.585-caliber, water capacity gross is 220.1 grains (as measured by AEM in AccuLoad3)

.505 Gibbs
.505-caliber, water capacity gross is 176.7 grains (as measured by AEM in AccuLoad3)

.550 Gibbs
.550-caliber, water capacity gross is 182.9 grains (as guessed by Rip)

quote:

Originally posted by Macifej:
Trivolver actually! Load Once! - Shoot Thrice!

Kidding of course!

I nominate shootaway as your crash test dummy. He has a snowmobile helmet he wears at the bench.

quote:

Originally posted by RIP:

quote:

Originally posted by Macifej:
Trivolver actually! Load Once! - Shoot Thrice!

Kidding of course!

I nominate shootaway as your crash test dummy. He has a snowmobile helmet he wears at the bench.

Who is shootaway and is he already brain damaged? This would be an asset!

The rifle goes to H.P. White for proofing and load validation. There's also the minor detail of mapping the recoil moment.

S&H 2-Bore Express - 700 grains of anything you want to load in it and get behind! The case weighs a pound and most of that is in the base. There's also a safety factor of 15:1 in the chamber area. Doubt any other shoulder fired rifle has that kind of ratio.....

A 577 Trex max load would exceed the pressure limits for the smaller .505 Gibbs head diameter that CZ roll stamps on their rifles in .505 Gibbs: about 55,000 psi.

Since the Trex has a bigger head and rim it will certainly have greater bolt thrust than the .550/.505 Gibbs at the same pressure.

>>> Pressure >>> velocity >>> KE

The .550 Gibbs will certainly be safer regarding action failure than a 577 Trex at any given pressure.

It will be a better platform for reaching "overkill" energies. More than enough ft-lbs there.

Rich,
Keep it down to about 55,000 psi and my little piggie will sleep better.

Combat Commander Macifej, Sir!
1-pound empty brass 2-Bore case! Did you mean 7000 grains of projectile (surely not a measley 700-grainer) to go with 7000 grains of case? Forgetting the exact powder charge, over 2 pounds per cartridge?

15:1 safety factor in the chamber? Does that include the back of the chamber as in the locking mechanism?

I wonder what safety factor is engineered into the CZ and other actions like a GMA?
1.5:1?
2:1?

Is this how some live on the ragged edge of chamber thrust?

577 Trex pressures, allowed max average:
53,000 CUP or 65,000 PSI or 4482 BAR
0.6880" head and rim diameter


Do a search on "shootaway" if you don't know the saga of his .458WinMag benchrest inaccuracy with a unique scope mounting system utilizing one scope ring, the front one, on a CZ.

That's 700 grains of powder sir and 3500 grains of projectile. The safety factor is a measure of the hoop and radial stresses of the barrel shank only. The breech block has, by design, an equivelant specifiction.

I'd guess you're right on with the CZ, don't know about the GMA. Would guess the WBY MK V is the strongest production action of reasonable size. All forged parts vs machined billet.

Safety factor = more material or stronger material or both. I like both!

I remember that guy with the one ring set up! I'll pass - he can't afford any more brain damage.

the 550 Gibbs and the 577 Belted mag express have legs due to the renaisance of the 505 gibbs and several sources of good brass.

with the advent of the new 550 diameter married to the Gibbs...
that is a helova monster.

the 577 BME is just a bolt action 577 Nitro and that is no small potatoes but on the gibbs case you can fit it into a CZ or ruger RSM ect that you can get into for about 2K.

The top end load goal for the 577 would be 750@ 2400 but I will stick to classic 750 @ 2050 thank you and 1600 fps for most everything.

Being that it is almost the same capacity as the original 577 you can use those loads for looooow preasure for a bolt gun and the same pachederm stopping performance as the 577 NE...just three down and one in the tube in case 4 elephants get "frisky"

quote:

I think you guys did a bang up job! Very clean job on the belt from what I can see. That's some serious horsepower in a standard rifle.

Thanks to Ed Hubel for making the cases and being the 577 BME engineer

The 550 is all Rich's handiwork

the 550 is more like a hockey goal, I get the goal, RNS gets the assist.

Thanks for the information RIP, I intend to work it up gradually, probably along the lines of 50fps increase a week until my shoulder says "that is enough!". It's definitely uncharted waters, but the Enfield action I have is pretty strong. That and the two part recoil system by Tom McCoy, recoil shield and field armor really tames the beast.

I'm elated that the load of N160 gave me 2156fps and 7,382ft/lbs of ME. I think 2200fps and 2" at 50yds for three rounds will make it a success; and commercially viable.

Rich
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Rich

The 550 Magnum will push a 700gr jacketed soft point out of a 24" barrel at just under 2300 fps with a case capicity of 154-156 gr. The 550 Gibbs should have about 192 gr capicity. You have almost 40 more gr capicity to increase the speed on the 700gr bullet. I know you are looking at 750gr but I thought having some data for the 700gr might shed some light on what the 550 Gibbs will do.

thanks Neal,

I am working with a jacketed bullet maker, and looking towards the heavier end of the equation. I would like an 800gr SP?Solid at about 2350-2400.
This is just recoil inurement taking place.

Rich
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Neal's cartridge and any commercially available action designed to .416 Rigby length and head size will easily handle 65,000 psi in unquestionable safety.

Lessee, what was Neal's tested pressure with 700-grainer approaching 2300 fps ...

(I do recall the .550 Magnum load with 800-grainer at 2100 fps in 24" barrel yielding 63,000 PSI.)

As stated by Neal:
.550 Gibbs case volume = 192 grains
.550 Magnum case volume = 155 grains

Then: .550 Gibbs case is 23.87% bigger volume, gross.

About 24% greater gross volume.

If you get Neal's pressure for 700-grainer at X velocity (2300 fps) in a 24" barrel ...

60,000 psi

RNS & RIP,

I have some jacketed 600gr SP's. I wanted to do a little cost-effective (read cheap!) work with cast bullets first. When the recoil limitation is reached with several powders we will have a true assessment of the cartridge's potential. I think it will be safe to take my top end loads with the 715gr cast and start there with a 600gr jacketed bullet. My friend is willing to experiment with various weights/shapes of soft point and solid bullets. We are going to look at weights from 600 to 650 to 700 to 750 to 800, and perhaps even heavier; and let the recoil factor say WHOA!!. Every cartridge has a balance point, where bullet weight and velocity reach their most effective point. 375 H&H...300gr. 416's...400gr. 458's...500gr...etc.

Tomorrow we test some more, and get some more data. I will also send Boomie some pictures of the rifle and loaded rounds.

Rich
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If you get 6% velocity gain for 24% case capacity gain, the ragged edge with a .550 Gibbs would mean 2438 fps with a 700-grainer at 60,000 PSI, in a 24" barrel, by "4:1 Rule of Thumb."

Rule of Thumb Number 2: Keep thumbs attached to hands and out of frontal lobes.

I think a 700-grain JRNSP and a 650-grain monometal copper FN solid would be perfect for these .550 cartridges. Hard cast lead? 700 to 800 grains, or lighter plinkers for the light express loads.

RIP,

opinion on the comparative performance on DG of the 650 jacketed at the speeds you expect VS that monster 881grain at about 1800-1900fps? Scenario is wounded Cape Buffalo or Elephant closing fast, maybe twenty feet out. Broadsword, or Claymore?

As an aside, I sent Boomie some pictures of loaded rounds, and the rifle with my CZ in 505 Gibbs for comparison.
The world will soon see my fuzzy face.

Rich
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them some respectable whiskers ya got there...good for protection gainst bugs on the harley I assume

I have this strange urge to watch "Miracle on 34th street"

The Geo Tracker is a chick magnet...dont get me started

Rich,
You better get a muzzle brake screwed onto that .550 Gibbs, at least until load development is done. You tell us what shoots best when you get through testing. Christmas in October.