quote:

Originally posted by RIP:
Jim,
Maybe I am delirious from sleep depravation right now (work).
But ...
Thanks for all the number crunching, but you are making my head spin when you get past the simple external ballistic programs.
From my shooting results, and my certain abilities to induce errors of measurement of those results, and using my simple programs,
I could buy the MTH BC of .426 as well as the Raptor BC of .296.
I am just going to use the KISS principle on this one.
And the lighter Raptor with poorer BC does shoot slightly flatter due to higher MV, by about 250 fps, as boom stick noted.

So how is it that the Raptor has better BC?

I am wondering if the bands and grooves on the sides of the brass, coarsely banded bullets, as well as the "noncontinuity" of the surface where plastic tip meets brass nose, causes "NonCon" turbulence and drag, heh, heh?

The much smoother surfaced, heavier, copper MTH nose and sides must be more slippery, improves BC.
Yes, if it could go faster, it would shoot flatter than the lighter brass Raptor.
Captain Obvious here, over ...

RIP,

You’re not delirious because I can’t figure out why it came out like it did.

I’m truly a dumbbell when it comes to computing bullet BC values and everything I’ve recently read (on line) indicates that the normal-standard G1 BC will give very high numbers for BT Spitzer style bullets which should be covered under either G5 or G7 (with G7 being targeted more towards the long VLD style BT Spitzer bullets).

Anyway, I identified the JBM program from the 6mmBR.com website…and here’s what they had to say on their Ballistics toggle:

quote:

Need ballistics data but don't have a program?

You're in luck. Check out JBM's real-time interactive online ballistics calculator. It's very fast, very accurate, and it includes windage corrections and time-to-target data. Just plug in bullet weight, BC, muzzle velocity, wind speed and angle and it will plot bullet trajectories from 50 to 1000 yards for you. The JBM program has also recently been updated with actual G7 values based on field tests by Byran Litz. CLICK HERE for the latest JBM Trajectory Calculator. You can even print out customized Trajectory Cards with Click Values.

So instead of using the JBM online ballistics computation capability I spent a few bucks and purchased their iPad software so that I could play with the program and find out if it’d do what I needed done.

The good thing, the JBM Ballistic program had places for me to key all of the information relating to ‘Projectile Characteristics’, ‘Sighting Characteristics’, Atmospheric Conditions’, ‘Output Options’, and ‘Calculations’…so I just keyed in the data that you’d reported when you did your target shooting into the correct data locations.

Unfortunately the key piece of information was missing – each bullet’s BC and where the BC was computed under G1 (the general catch-all grouping) or under the G5 or G7 (the two BT Spitzer bullet categories). So I had to create a ‘custom bullet’ with a WAG BC value so that I could compare the program’s trajectory output vis-à-vis your actual 100yd and 300yd target values.

I played with the program for each bullet separately using the G1, G5, and G7 Drag Models to identify which specific WAG BC value that perfectly matched your 100yd and 300yd values…thus identifying each specific G1, G5, and G7 BC for the two bullets.

Kind of ass backwards way of doing it, but now I can using one of the three bullet BCs and the BC’s relating G1-G7 drag model, rekeying your stated values, and perfectly replicate your 100yd and 300yd target values every time. I can also play with the 100yd sighting value and identify the new trajectory model.

All we need is for you to reload a stack of 49-10 ammo, have at least two chronographs to record MV and target impact velocity, capture all and then re-fire the MTH and Raptor at 100yds, 300yds, and 600yds and then someone can use a ‘high dollar’ ballistics program to validate the true BC under G1 and G7 and we’ll all be good to go with our reloading and ballistics software packages to run ‘what ifs’ till our hearts content.

Hey, this was just one of those things to kill time when you can’t sleep at night!

quote:

Originally posted by boom stick:
Would be an interesting trajectory test to shoot the same velocity. In terms of real world advantage the minimal bearing surface brass banded bullets gain FPS at the same pressure. If you can load them faster and same pressure to shoot flatter to give more terminal damage that is a win win win scenario. The MTH will be flatter past 400 yards than the raptor no doubt. The MTH will outshine from 400-600 yards. At 2,900 I think the Raptor would have a functional sheer distance of at least 400 yards.

quote:

Originally posted by RIP:
boom stick,
I think we are at the practical limits for speed on both bullets, at least in my rifles.
The heavier MTH with better BC still delivers more energy at 300 yards,
and it's margin over the Raptor increases with longer range.
Both can be zeroed to be useful from zero to 300 yards, with no hold-over on the largest PG.
Might have to be more careful on dik dik.

Guys I don’t know what to say. We’re dealing with a shorter heavier aerodynamic bullet vis-à-vis a longer lighter aerodynamic bullet.

Do the bands on the Raptor inhibit airflow? I’m not sure they do as the .500 caliber Raptors are designed with the HP upper band blending with the BBW#13 nose so with the Talon tip inserted you’re looking as a pretty aerodynamic line from the tinny meplat through the upper driving band and ending with a long aerodynamic BT. I have a feeling that the airflow isn’t disrupted by the lower three bands as I believe the air flow over the top of the bands.

Do the bands on the MTH inhibit airflow? This one I’m not sure of… Perhaps the Seal Tite band inhibits airflow. Or perhaps the airflow from the aerodynamic nose is merely deflected slightly as it encounters the Seal Tite band such that the airflow is above the banding until it reaches the short BT. Definitely raises questions.

Wouldn’t it be interesting if by happenstance that with the development of the Talon tipped ESP Raptor that we’ve indirectly identified an extremely aerodynamic shape?

Perhaps Dan can shed some light on all of this once he’s returned from Africa and had a chance to rest up.

Oh yes…to answer both of your questions…if the G1-G7 values for the two bullets hold up the Raptor has a flatter trajectory over 900yds than the MTH…and at 900yds both bullets are at or above their documents nose expansion velocity. Tomorrow I’ll try to piece together the multiple printouts that I have which shows each bullets performance under the noted BC drag profiles.

This necked to .500 could make a bigger brother.

quote:

Originally posted by boom stick:
This necked to .500 could make a bigger brother.

The above looks a bit like a 450 Rigby.

It has been necked to the 470 Mbogo and 500 Mbogo. there is certainly room for a 490 Mbogo, though it requires the magnum length long action, as opposed to the 49-10 and 500 AccRel which fit in a standard "270Win, 375Ruger"-long action.

Yes 450 Rigby. Would leave 20 thou shoulders. Just enough.

You just need to remember the case walls are not as thick on the 450 Rigby brass as the 338 Lapua Magnum (Lapua brand/manufacture) brass. I have some Hornady' 450 Rigby brass and the shoulder caved on me when I ran it into my Hornady Custom 338-500 Expander Die. Run the Lapua' 338 Lapua Magnum case into the same die results in a perfect expanded .500 caliber case. And I also get the same results by first running my Lapua' 338 Lapua Magnum brass into my Hornady' Custom 338-450 Expander Die and then running the case into my 338-500 expander die - perfect formed .500 caliber case.

So you'll definately need to use one or more neck expansions from .458 to .500 so you don't collapse the shoulder-shoulder/neck section of the case. At least that's my experience.

quote:

Originally posted by 416Tanzan:

The above looks a bit like a 450 Rigby.

It has been necked to the 470 Mbogo and 500 Mbogo. there is certainly room for a 490 Mbogo, though it requires the magnum length long action, as opposed to the 49-10 and 500 AccRel which fit in a standard "270Win, 375Ruger"-long action.

490 Mbogo? I thought about that once, but I went and laid down until the urge went away.

WE BAND OF FORTY-NINE TENNERS: THE THREE MUSKETEERS

Not quite 2 years since the last post – but thought I’d resurrect it anyways…

Just posted this over in the Custom Built Rifles, Steve Button Custom Metal Work thread…
http://forums.accuratereloadin...871080102#6871080102

quote:

This is an old thread – but all delays in finishing the rifles have totally been my fault. That said, I thought I’d at least update with a few new photos.

I do apologize for the quality of the photos as I don’t have a “setup for photo work” – it’s all makeshift with handheld camera.

Here’s a full-length shot but photo buggers the look as the rifles are only 1” difference in overall length:


Closer look in the action area:


Yep, 3-position left hand safeties by Satterlee:


Top view of the .500 caliber rifle with three 12.7x68 Magnum cartridges in the magazine:


Top view of the .500 caliber rifle thumbing 4th round into the magazine:


Top view of the .500 caliber rifle with bolt picking up 4th round for chambering:


As can be seen, there is glass work needed to better fit the barreled actions to the stocks in both rifles. Metalwork finish also needed. Currently I’m still noodling over the metalwork finish (leaning towards Cerakote) and what finish (paint scheme) I’ll have applied to the synthetic stocks.

I do have two very nice matched pair of English Walnut Exhibition Grande blanks for future stock work; the paired blanks handpicked by Roger Varde, Victoria, Australia.



Thanks for participating…

I’m no Michael with the photos – mine really suck!

Anyway… Ron you can see that three of the 50 Bats fit in the Wiebe 4MJ box with room to thumb the 4th round below the bolt. Couldn’t photograph it cause I only have two hands but I did cycle the dummy rounds and all feed without issue. I’m happy.

As noted in the post extract, I need to have a finish applied to the metalwork and then glasswork done on the stock to eliminate the metalwork gaps. The unfinished CM with its quasi SS finish is growing on me though...

Neat use of 404 Jeffery bottom metal,
and great wood, if you like that sort of thing.

The Jeffery bottom metal does work nicely. You have to remember - any M98 Mauser with custom metalwork deserves to be dressed up occasionally!

quote:

I’m no Michael with the photos – mine really suck!

No Cappy, looks good to me!

EXCELLENT WOOD, and despite RIP, we do like that sorta thing!

Looking good.........

Thanks Michael.

quote:

Originally posted by michael458:

EXCELLENT WOOD, and despite RIP, we do like that sorta thing!

Looking good.........

Doc M,

I definitely resemble your remark, but don't resent it one bit, for it is very truthful.

There are no flies on the 12.7x68mm Magnum aka "50 Bateleur,"
especially since it beats the topdog MIB cartridge (500 MDM) by a small ballistic margin.

The 500 Bateleur was hatched from the 50 Bateleur by merely necking it up from .500 to .510 caliber,
and lengthening the neck a wee bit,
from max brass length of 2.657" for the 50 Bateleur,
to max brass length of 2.700" for the 500 Bateleur.
They are both swell.
The 400 Bateleur will merely be a neck-up of .338LM to .408 (true .400-bore) and shortening of that cartridge from 2.724" to 2.700" max brass length.
Here at RIP we only blow out the .338 LM shoulder when necessary, like for the 50 Bateleur and 500 Bateleur.

500 Bateleur must be made from basic cylindrical .338 LM brass, due to concerns with neck splits.
No problems with the 50 Bateleur in forming from blown-out .338LM, but it must be kept shorter than 2.700" to do that.
Even the 400 Bateleur which is a simple neck-up of .338 LM, barely makes it to +2.690" when necked up from .338 caliber,
that starts at 2.724" official (CIP) max brass length.

The 12.7x68mm Magnum/50 Bateleur would need to be formed from basic cylindrical brass to get it out to 2.700", like the 500 Bateleur.

Jim might want to call his .423/.338LM cartridge the "404 Bateleur?"
A 404 Bateleur for long range smack and a 50 bateleur for up close smack is quite a nice combo,
mutual backup.
They are both adequate for anything from spitting distance to 300 yards.


Also, Jim,
I forget the length and shoulder specs on your .423/.338 LM, since that one is your independent development.
It can beat the 404 Jeffery if you want to use higher pressures than the 404 Jeffery,
and that is certainly no problem with .338 LM brass, good to 68 Kpsi.
Is it a straight neck-up or has there been any shoulder blow-out/improvement?

This is important for official R.I.P. certification purposes.
Also whether you wish to have it registered as the "404 Bateleur?"

Official Riflecrank Internationale Permanente certification desired?

Ron, I'll send you an email after I finish writing it. Not hiding anything from the group; I pooched the reamer specs, so it's just a long message...