The Nef firing pin is big enough in diameter that
it won't pierce CCI shotgun primers with 25-30
lb springs on the hammer. That is what mine has equivalent
of with the extra coil spring I cobbled up behind
the hammer to help the original spring..

DO NOT go over 15gr of Blue Dot starter powder. You want the
ignition of the HBMG and the pressure rise to be a linear
gain to match the powder increases. Adding more starting powder
changes HBMG burn rate. To much starter and it won't act like
HBMG on its way up. With Rob's lighter slug you can go
up 10gr HBMG at a time like Rob says. Brett in MN on his
starter powder loads uses the real thin .030" overshot
plastic over the Blue Dot then adds main charge. I used heavy copy
paper cut in 12ga size circles.I've split .050" overshot
cards with razor blade and they work. Works better than
tissue as it is easy to keep level in case.

I have to explain something. When it comes to the starter loads
I tested, I used DB stick RL powders as I wasn't using any slugs with
those loads heavier than 870gr at the time. And 600gr, 730gr slugs the
RL15 worked and 870gr RL19 worked. The way you say the HBMG
is doing it may be an exellent powder for these starter powder loads.
Up to whatever velocity it will give, then if you want more speed
with 1400gr slug go to RL25. Keep up the good work.Ed

Rob,
If I have to resort to pounding CCI-35 primers again, I will wear my "shootaway shooting helmet" with visor and "Thor Gloves."
Hopefully the AmmoMaster primer tools will work on the "Lord of the Rings" cases second time around.

Ed,
Thanks for the tips.
15 grains of Blue Dot, okay, no more.
I like my single-ply Kleenex circles, however.
Cut small enough diameter, they settle in like a falling feather, probably get shredded as soon as the H50BMG powder is pressed in, but do serve to segregate the powders enough once locked in place by a stuffed-case load.

I will start the chronographing with Rob's 1085-grain Brass Darwins and 130 grains of H50BMG, going up by 10-grain increments.

The .729" brass bullet diameter may be a little undersize for the NEF rifling, but that is adequate for accuracy, and should be perfect for the custom barrels if rifling is .729" groove as advertized there.

I am still waiting for the Lee sizer to make my lead slugs .730". When cast in harder alloys they are slightly bigger and lighter and need to be sized down to keep pressures down for the initial load development with heavier lead slugs.

Rob...You've got mail.

Ready to chronograph these when the rain stops.
Expect tomorrow.
Rob's 1085-grain Brass Darwins.
Increment is 10 grains of H50BMG, 3 shots each, 130-170 grains.
15 grains of Alliant Blue Dot "starter."
1-ply Kleenex powder segregation.
Fiber wads and Nitro Cards in various combinations to lock everything tight.
CCI-209 primer, which is about the mildest of the 209's.
Bullets blacked. Chronograph shielded.
RMC 3.5" brass.
COL is a tight 4.040" this time.



I did break something else, the linkage on the MEC Super Sizer proved to be weaker than the RMC case mouths.
It works great on the 50BMG thin necks.
I'll get another one, I like them so much.
Will keep one in 12Ga for hull bases and 20Ga for 12GaFH NoHboHzo brass.

Of course the 5C colletts are easier with the 50 BMG brass too.
With the RMC brass I have to hammer the handle on the collett closer with a rubber mallet.
I suppose I will breaking the handle on the collett closer fixture next.
I will certainly anneal the RMC case mouths for the reloads, with 1400-grain Lead Darwins.

RIP
Nice looking rounds you have there.

Just a few question's.
1) where did you get the collett closer from? I have never seen one before!

2) On the collett closer, can you not put an extention onto the arm, even if its a bit of tube pipeing over the original handel. I take it it can be removed with a grub screw? If so, I'd look at getting a replacement knocked up with a longer handel.

3)The MEC linkage, can it not be welded back on. If not would it not be adviseable to get another made up from a suitable bit of either tool steel or stainless steel blank? I take it there would be an engineering mob near you somewhere, no?

Gibs,
Thanks for the kind comment on the ammo.
No worries about kabooms, thank you.

Nevada Shotgun, LLC (Rob) directed me to MSC Direct for the 5C collets and fixture.
You can find plenty about them a few pages back in this thread.

A cheater pipe on the cheap collett fixture handle is easy. So is the rubber mallet.

My fixture is a cheap Chinese one.
There are much better available.

It would cost more to rebuild the MEC than to by another one. Time and money.
It is more than adequate for the 50BMG based brass, as made by MEC.

Anything will work better on the RMC brass after a proper neck annealing.
I do not think my cases got any annealing by RMC.
I sure can't tell it if RMC annealed it.

Real 12GaFH loading dies and brass would be best of all,
and if Nevada Shotgun, LLC doesn't come out with them soon, sumbuddy else will.

I am still waiting for brass for the .395 Tatanka from Qualcart.

Everything else in my tremendously innovative line of wildcats is complete.
Boredom was setting in, hence the need for Rob's 12GaFH: Never a dull moment with that on the burner.
I am an exclusive "club of one" member on all but two of them.

Find below, a link to MSC, listed in the exclusive suppliers of RIP, VLLC :

RIP
Thx for the info matey. I finaly manage to source a supplier of the collet fixture in the UK. The only ones that will do international sales and also use paypal. It would appear that after much searching (3 hours) for a supplier over here, there aint a bloody one!

As to the MEC supersizer an the RMC brass issue, if it is cheaper to get another and you sure that annealing the case will fix the issue I can understand. If the RMC brass needs that much belting to get it to crimp, I'd say its a fair bet they are not annealing the cases. Thinking about it, why would they! Also it leads me to believe that the cases from RMC are strong enough to be used in a press with out any fear of a rim issue. They sound like real ol tough buggers.

If we can get 12GFH Dies that work in the ammomaster press that be a real boon, its whats needed atm I feel. A reliable easy reloading method.

No chronographic joy in Mudville today, too wet and windy even to use my artificial lighting outdoors.

quote:

Originally posted by RIP:
No chronographic joy in Mudville today, too wet and windy even to use my artificial lighting outdoors.

TVA sludge roaring northbound...??

Macifej,
Nope, I am not in that drainage. We just have to accept the effluent of everything from Pittsburg, Cincinatti, Louisville, and such floating by in the Ohio River. I am upstream from any TVA toxicity.
If not for the TVA ... Possum Hollow, Kentucky would not have had electricity finally make it to them in the mid 1950's. They are not all bad.

Well at least your tap water doesn't taste & smell like low tide as declared pure by the local Cartel de Agua...

RIP- Totally understand and we will just have to wait till the weather clears. When I get back to work, I'm going to make a few FL sizers for you guys. They will be Lee Loader style for simplicity. I wrote a simple prgm to do the boring. Maybe one for the .50BMG brass and a second for the RMC brass. Just stick it in a vise lube the case and close the vise. Pound out the brass with a brass rod and your ready to load. I'm going to set it up to produce a .728 ID at the case mouth. The tapered ends of the brass Darwins should make loading easy and they will have lots of neck tension. . They will be cheap to make and once hardened, virtually indestructable. They make the whole rim thing a moot point. I sized 10 cases in 15 minutes with mine. I will also make some steel rims, but unless you have a minimum chamber its still a enourmous amount of force needed to size these cases just due to their surface area. To use a ammomaster, we may just have to settle for neck sizing only with steel rims. I doubt the RMC case rims will survive though. We will see.
Assuming the RMC cases work ok with 170grs of H50BMG, my guess is you will still need to keep increasing the load till you hit 220grs of powder. I have fired my NEF with as much as 240grs and the recoil really wasnt bad at all. It did get my attention at 240grs though. My calculations say its still in the 26Kpsi range and the brass sure acted like it. The RMC brass should be fine. If you remember my first .600OK brass was 760 half hard and had a wall thickness of 0.13 ( one heck of alot less than the RMC stuff). I pushed that stuff up to 36Kpsi and had no isssues at all. You are well served to be cautious and work up slowly, however, I dont think that big smile will appear till you get to 220grs or so.-Rob

Big Chief Nobozo has spoken!

Thunderstick me have now has big-hole chamber and firing pin blow like kiss of squaw!

Big Medicine Thunderstick must have tight chamber and firing pin blow like brave in battle, counting coup on enemy!!

Indians vow to endeavor to persevere!

28GA FH new slug.. The Lyman cast 20ga slug made to
fit in a 20ga shotcup for 20 ga slug hunters, works perfect
in the 28GA FH brass case. It is a hollowbases hourglass
shaped 362 gr slug. No wadcups or wads needed, loaded
right on powder. It is the slug you buy the molds to cast
your own or you can buy them from guys who cast for
sale. I use slow rifle powders in case so no air space,
they fill to the slugs. I got 2900 with moderate case
expansion and it hits target straight on, from a smooth
28ga heavy barrel on 695 Mossberg bolt action.

Other new info on primers. Some of the guns can't have the
firing pins or hammers beefed up easy like my Enfields
With some magnum primers with hard cups you get delayed
ignition if hammer doesn't have perfect hit and high strength.
One test with a small diameter case/bore that any primer will
ignite slow powders fine with good firing pin spring would
show delayed ignition with shotgun battery cup style 209
CCI Mag and 209 Federal Mag primers, and when I tested them
in cases with just the primers, they only put in a small dent
when they fired, but WIN 209, REM 209, RWS 209(used in
Brenekkes, Lightfields, Hastings), dented in much more when
firing just the primer. And with the smaller bore you had fire out
the end of the barrel, so you could compare primer strength
visually. The REM 209 was as good or better than CCI and FED
209 Mag Primers. The WIN and RWS was close behind. We put
the REM in same case/gun where that we had delayed ignition
and it fired instantly, no delay. The two mag primer brands have
the primer insert in cup rounded a lot and little harder metal,
and the other 3 metal cup insert is almost flat and slightly
softer. It is easier to get a better more solid strike and dent.
I always figured mag primers were best in our hopped
up shotgun loads but not anymore. It took a while but I finally got
everything around for proper test. Hopped up loads(regular also)
we have talked about, use REM 209, where the firing pins
and hammers can't be strengthened. Even loads with Longshot,
Blue Dot, Steel, HS6-7, etc.
Hope this helps.....ED

Nice one Ed. So the REM 209 primers are the way to go. Hmm, RIP can you see if a REM 209 will light up a test RMC casing of H50BMG powder with nothing but a tight wad/plug over the powder. Bit like you'd use to fireform a BMG case. Use 240grs of H50BMG for the test. No Projectile.

I'd be interested to see if it will set off all the H50BMG powder!

Thx

Gibs,
I will not do that test.
I would never expect any 209 primer without a duplex/starter-powder load to be adequate for a case full of H50BMG.
The differences between the various makes of 209 shotgun primers are minor versus the difference between a shotgun primer and a 50BMG primer.
There is no problem setting off the H50BMG with the Blue Dot starter charge, using the CCI-209 in the RMC case.
The 209 primers are irrelevant to Rob's BMG-based case full of H50BMG powder, which uses a CCI-35 primer with a really stout cup needing denting by a stout firing pin blow.

Do we need to retrofit Rob's cases with 209 primers?

Then I could use 209's and Blue Dot and not have to beef up the firing pin on the next NEF-er.

I've got an old Gun Parts catalog and will look for that schematic showing the firing pin and spring in the NEF-er.

Make a stouter spring, requiring just the shaping with a thicker spring wire?
Could two or three of the factory springs be fitted into the action to double or triple it up?

Make a firing pin that protrudes .085" as Ed says.
Could a pin extension be welded on and polished smooth?

Hmm, now if I can just find a gunsmith that will chamber this thing in one of my Marlins!

NP's RIP, I'll do it myself when i get the bits, no biggy. Thx anyway.

I had a look at the NEF;s spring and all it will take is making a stronger one. No Big deal. Its double wound each side of the Hammer so it will require a lathe set-up to make, but is a simple part. I've already figured out how to do it. I think two springs would cause hammer interference issues. Ed says all you need to do add some more clearance to the transfer bar to get the added protrusion. Alternatively just cut back the pin a little.
I'm sticking with .50BMG primers because under no circumstances will I risk a double concussion. A double concussion is thought to occur if a primer fails to completely ignite the main charge pushing most of the powder and bullet well into the barrel in effect creating an obstruction. The main charge then ignites and kaboom. This whole process occurs in just milliseconds. I doubt the NEF would survive one. Not saying it will happen, but no sense taking unnecessary risks for a .50 cent spring! I'm also still unconvinced that the NEF's wont light off .50BMG primers as is, if they are properly seated and armed. Nevertheless, beefing things up wont hurt anything and is quite prudent.Just gotta order a few different guage spring wire rolls. Make one, make a dozen.-Rob

Ok, the problem I have over here in Western Australia is this. I only have on my licence a .22mag, a 45/70, a .308W and the old 12G. Now because of that, the only ammo I'm allowed to buy is .22, 45/70, 308W and 12G and the PARTS to make said ammo. I'm not allowed by LAW to buy parts for say a .50CAL! that includes BRASS, PRIMERS, PROJECTILE, Oddly enough I can buy any powder I damn well like, go figure that one out!!!! So I have to work out whats the absolute slowest powder I can light off with a shotgun primer, the ABSOLUTE slowest. Now if these REM 209 are a better bang for ya buck - I'd like to know just what they will light up accordingly. So I guess when my RMC casing's arrive I'll be getting a few powders an having a play.

Gib- You can fire any powder with starter powder.
Best for 12ga is RL15. up to 750 gr slugs, RL 19
for heavier to 1000 gr. That said the The REM or the
Mag primers still by themselves will ONLY fire off VV110,
IMR 4759, 4227. That's what worked in powders I have here.

{You need to get a 28ga on the license,, then you'd get
28ga RMC brass, and you could use all slower powders.}

Understand that I didn't say to use 209 primers alone to light
up slow powders like HBMG, RL25-22-19,etc, in 12-16-20 ga cases.
The case diameters are too big and you have to use starter
powder. I did primer test in my 28ga FH(550 cal) in gun with firing
pin that I couldn't beef up the spring. And was testing with
a powder that was a little hard to start. It fired off fine
in my 28ga Enfield. So I rounded up 5 brands of primers and
did the test just using primers to get a comparison, and the
two rounded hard mag primers didn't dent hardly at all, while
all the others dented fine. And one the REM had more fire out
the barrel(small 28ga,550cal dimeter bbl made this possible) than
the two harder to dent magnum ones. In the Enfield
with real strong firing pin the mag ones had fire out the
barrel about the same as REM. I have guys tell me that
large rifle primers used in brass 12ga cases are better than
mag 209s, but it is just the case that the large rifle primers
are flat on top, not rounded, take a strike better and dent in
properly to fire off better. A properly ignited 209 has more fire
out the end of a 28ga, .550 cal barrel than large rifle one
I've know because I've fired large rifle ones in Neal's 550 Mag case
in same size barrel. When I put a gun togther I fire a few primers
first to check ignition first to make sure it's working.Ed

Gibs- I thought you Aussies had the .50BMG case market all tied up. Where did all that stuff go from the Mad Max movies? Doesnt ol Mel Gibson have a big warehouse full of that stuff in Darwin? You should be able to buy my RIMS as they say SHOTGUN on them in English to fool the bureaucrats into complacency. Just Kidding you!-Rob

Ed
Thax matey for clearing that up, I missunderstood your post about what you were fireing the primers in.

Rob
I wish matey I wish. If Mel had a secret stash of .50Cal bits I'd do him some serious harm for not sharing !

Bloody terrific, now I cant find RL15 or RL19 equivalent on the ADI Powder equivalents chart!
This just gets better an better.
ADI Powder's

Can anyone see them ? Could I use AR2205 as a starter ?

Gibs- I thought Mel had a quad .50 mounted on the back of a Toyota PU for those delicate social situations that occur from time to time in the outback. You need a serious amount of brass to make a proper impression on the biker gangs with one of those. Why wont he share with you? I doubt he reloads!-Rob

Mate all I can say is... TO MUCH MM and I dont mean the chocolates!

And we dont call em Pick Ups its a UTE mate. ok (Quad 50's included)

Glad to help.You must use shotgun powder for starter
powder, like Blue Dot,or any slower flake shotgun powders.
Like 800X flake, Scott 1500 flake,IMR 4756 flake.
Another reason I run primer comparison tests
is quite a few guys reloading slug/sabots and even
factory loads, in some guns, including new guns are
having delayed or no ignition. Few big discussions
on it over on Shotgun World. So I decided to find
out after I had the delayed ignition on the 28GA FH
in brass cases with slow ball powder, with a gun with
average firing pin power. The click bang sound is
scary to say the least, as what Rob mentioned above,
secondary ignition hitting an obstacle made by a slug
wedged in the bore from a poor primary ignition,
can blowup a gun. In 4 years I've had about 30 click
bangs and I don't want any more.No more reloading
hard round top primers.My 8ga cases that come primed
are REM and have REM 209 primers. Everything else
will be reloaded with the same REM primer, that uses
shotgun primers.

I've never had delayed ignition with bmg primered cases,
my 700s or the 12GA FH. The big primer can burn
pine stumps if needed. Ed

I've sold my soul!!!

Put an order in for a NEF Ultra Slug Hunter at the local Dick's this afternoon.

I've been lucky enough in the past to just use department ammo so I've never had to reload before. Now I must start!

Rob, sent you a PM on getting some of your finely crafted metal bits once you get whatever FFL stuff you need sorted out.

To everyone else who has contributed to this Demon In Steel, THANK YOU!

I'd originally found this forum and topic while looking into the double rifle stuff that I'll never be able to afford. And now, I'm hooked!

Powertrip,
Alrighty then!
This 12GaFH stuff is like being a kid again! Welcome to this Professional Small Boy's Club!

Gibs,
I understand "ute" for utility vehicle,
But what the hell is "bakkie" for in RSA?
A pickum-up truck is simply called "sportscar" in Kentucky.

AR2208 = Varget Extreme, and that will do the RL-15 thing better than RL-15. I would happily switch any RL-15 load
for a Varget load, and that is AR2208 relabled. I find RL-15 and Varget to be about one grain apart in my 404 Jeffery loads,
like 81 grains of Varget equaled 80 grains of RL-15 in my rifle and loads.
The burn rate table is only an approximation, not an absolute, as they admit.
No worries on that one, mate.

As for the RL-19, I would just go with the AR2209 and lower by 5% from the RL-19 amount and work up.
That is H4350 Extreme, tied with Varget for the most useful powder in the universe.
AR2209 = H4350 Extreme.

Here is a schematic of an old H&R "Single Barrel Shotgun," from an old The GUN PARTS Corporation catalog (#21).

I have not taken apart the firing mechanism of my NEF-er No. 2, yet.
Is it similar to this in the Ultra Slug?

Firing Pin: part # 12
Firing Pin Return Spring: # 13
Hammer Spring: # 21



Here is a cartoon of the transfer bar system of the current Ultra Slug:



And some shotshell primer comparisons done by Lyman and Hodgdon for our 12-Gauge entertainment.
There are no absolutes, everything is relative ... except the CCI-209 seems to be the gentlest in all three trials,
and not as hot as the Remington-209P in all three trials shown.

And the CCI-209M is hotter than the Remington-209P and the CCI-209 in the two Hodgdon trials,
a 1-1/8 ounce heavy target load and a 7/8 ounce light target load.

With the heavy load, both the Remington-209P and the CCI-209M are on the lower pressure and velocity side,
though pressure and velocity do not correlate strictly linearly.
The Federal-209A is highest for pressure and velocity with the heavy load.

In the light target load, the CCI-209M is hottest, highest pressure and velocity,
and the Federal-209A is next ... but the Remington-209P is challenging the CCI-209 for most mild mannered.







HOO HA!

Can the base of the firing pin be dressed-down/faced-off to effectively lengthen the "pin part" of the firing pin
and allow it to protrude farther under the hammer blow?

What transfer bar fiddling might that lead to?

That hammer spring looks simple to make, for a qualified spring maker.

THE NEF ULTRA has same parts as diagram and same
transfer bar setup and parts. Major difference is it is
a heatreated stronger action.Those pics are
a big help and show what needs done to get pin
out further for better strike.
You leave the pin as it is and lengthen front of
the hammer slot that the top of hammer hits and that the
transfer bar hits.The front of the hammer slot is a stop
that regulates how far they push out the pin. You cock gun
and take a small punch and push firing pin forward you will see
it goes beyond the hammer slot and sticks out much more than needed.
So .020" off the hammer slot front gets you the same added to how
far the pin sticks out.The pin has a spring that retracts it
when the hammer bar drops as you release trigger.

Primers-- If you get them ignited the same, they are all do
about the same, but the REM and WIN ignites best with marginal firing
pin and hammer strength. And that was the purpose of
my testing -- to find the best relable trouble free primer
for ignition in all guns with average or strong hammers.
Now those tests the companies run on the primers were with
spikey, finicky fast shotgun powders, if you ran test with our
4227 loads in the 14,000 psi range, using same brass/plastic 3.5" case
and loading stuff, they would all be within 3% of each other.
Which is why we found these powders to build slug loads
easy and safe, without a pressure lab and 6" diameter barrels
in an underground concrete bunker.Ed

Ah ha! Hammer slot! Thanks Ed!
Good pointer! That dog will hunt.

That spring sure looks easy to make. Is that the same spring in the Ultra? I saw a different version in a shotgun dissasembly guide for the H&R? Have not taken mine apart yet to see for myself. -Rob

quote:

Gibs,
But what the hell is "bakkie" for in RSA?

RIP

I'm not following you here, sorry. I'd need a bit more info as to what context this was in. The only thing that I can think "Bakkie" refers to is tobacco. But as to "RSA" I havn't a bloody qlue. sorry.

Ok, I'm now more confused than before (yeah I know, pain in the butt). Ed your saying to use a slow SG powder, as a starter, best I can work out would be AP100, but then a full casing of AR2205 (IMR4227) will light off fine with a SG primer. Then you say try RL15/19 which RIP says is about the same as AR2208/AR2209. Is this still a starter or the main charge?

The main charge I would like to use is AR2218.
So I use a 209 primer of some kind, a starter powder like AP100 (but I think I could use AR2205) or do I use AR2208/AR2209 as a stater and then the main charge of AR2218.

Or is it a 209 primer of some kind, a starter powder like AP100/AR2205 and then the main charge of AR2208/AR2209 and dont use AR2218.

Since what we are after is a slow build up of pressure and not a spike, I'd have thought that the slower the starter powder that you could use the better it would be or the closer the burn rates of the powders the better it would be?

Yes that spring # 21 in pic is the same.
And it is shown with about a 120 degrees of
arc between sping arms. I've had some much
less than that which made them weaker.
If you make your own go with a 25% heavier
wire for more power.There is room for extra
thickness on the pin that it is on, which is
same pin as hammer pivots on.Rob, if you make
some get me some. Don't make short arm of spring
shorter as that is needed to hook peg on the hammer.
The other long arm of the spring rests against
the inside bottom of the action down next to where the
trigger group slides into bottom..
I noticed there is a lot of room behind the hammer
in the action, even when cocked-- SO an experiment......
I am going to drill a pin in the right side and
put the long side of the spring up on it thus
increasing spring tension, and see how that works. Ed

Ed- That spring is a piece of cake. I'll make a bunch of them.-Rob

That will be great Rob.

Gibs I misunderstood. I thought you wanted
to use that as a starter powder.
You use slow shotgun powders for starter
powder only with those slower rifle
powders that the regular shotgun primers
won't ignite by themselves. With your 2205
the same as 4227 then don't use starter.
The other slower powders use starter.
But the best ones to use a starter powder
on is stick powders and preferably the
doublebase stick powders like RL-15-19-etc.
Going to slower as the slugs get heavier.
Don't use a starter on ball powders, except
the super slow military types.Ed

Good spring info.
Rob, have fun digging out that spring, trust Ed, but verify. I will too.

Gibs,
Bakkie is Afrikaans slang, for a Kentucky sportscar, methinks.

I have learned what little I know about this from Ed and Rob, just getting started on 12GaFH loads myself,
but have handloaded for pipsqueaks up to 50-caliber for last 30 years:

AP100 (close to Blue Dot) will be your starter powder for 209 primers and medium to slow RIFLE powders.

Use 209 primer and 15 grains of AP100 starter with these bullet/slug and powder combos:

400-grainers: AR2206/Benchmark/10-X/IMR3031
700-grainers: AR2208/Varget/RL-15
1000-grainers: AR2209/H4350/RL-19
1400-grainers: AR2218/H50BMG

Some overlap will occur, but that is a basic scheme.

AR2205 is H4227, like IMR4227, a slow shotgun powder/magnum handgun powder.
Use that with 209 primer and no starter powder.

How am I doing Ed?

My experiments so far:

65 grains of IMR4227 with 209 primer in 3.5" plastic hull moves the 1400-grainer out
at over 1000 fps: this would be a starting load in the RMC case.

Blue Dot starter (15 grains) with 209 primer and 1085-grain Brass Darwin in RMC case: started at 120-grain H50BMG charge.
Will continue with 130-grain and work up by 10-grain steps, toward 200 grains, chronographing as I go.
Just being cautious, in new territory.
Will switch to 1400 grainers with H50BMG, and consider going to H4350 with 1000-grainers and Varget with 700-grainers.
Nitro cards and fiber wads seem to work well to fill the cases,
a must until full case powder charges are approached.

RIP,

In RSA the load bay of a truck is called the "bak". The diminutive form of "bak" is "bakkie". Therefore, a smaller vehicle with a "bak" is called a "bakkie". Why a larger vehicle with a load bay is not called a "bak", I cannot say.

V_Varrior,
Is that you Chris?
Thanks for the linguistic help.
I see that "bak" is like "back" as in "back of the truck."
So the cute little cruiser or rover is a "bakkie" as compared to a 26-foot box truck.

"Baby's got bakkie" would be what a bro' might say about a well equipped woman,
whether referring to her Toyota or her fanny, eh?

Lead slug reasoning in the 12GaFH:
Randy Garrett says a super heavy hard lead slug at 1400 fps will out-penetrate anything.

I think if I get a 1400-grainer up to 1400 fps with a hard cast FN "hammerhead" slug, that will be plenty of fun.
No concerns about gas checks, excessive leading, or shattering of the bullet at such sedate velocity.
All the annoyances of cast bullets in smaller bores at higher velocity will be gone.
...Only recoil to deal with, a good trade.

Of course lighter weight aluminum, brass, or copper monometal slugs at higher velocity (solids or softs)
could be better in various specialized applications.

RIP- Correction- Randy Garrett says a 500gr slug at 1400fps ( Hard Cast of special alloys known only to him) will out-penetrate anything. You have nearly three times the weight at same velocity, thus you will be able to out-penetrate the- un penetratable! What ever you do, Don't drop those cartridges or Gibs could be a victim of a AD down there? -Rob

How about a steel insert "disk on a stick" (like a roofing nail) press fitted
into the center-drilled nose of the lead Darwin,
presenting nose-forward a hardened-steel, sharp-edged disk matching the FN meplat diameter?

That will really be "randy."
12GaFH ready for elephant and blue whale.

I am going to load some 3.5" plastic hulls with steel BB (in the steel-duty plastic cup-wad)
to see how the rifled bore NEF-er patterns with that.

Also will load four to six 50-caliber balls as a "big-buckshot" load, whatever will fit,
and see how that patterns too, for 12GaFH versatility.