I have been thinking about putting together a .500 A-Square and had a question. My thought was to simply buy a laminated stock CZ in .416 Rigby and have it re-barreled. If I decide to go that route, anyone have a suggestion on a good gunsmith? Any other suggestions as to how it might be done.

Dave

+ 1 on buying a CZ Rigby as base rifle

Three letters: AHR.

They can fix you right up.

One of these years the Satterlee Stainless Magnum Mauser action (SN: SSMM0001) may be finished up as a 300 Lapua Magnum, and turned into a switch-barrel: 300Lapua/500Mbogo

Until then, I have done what you suggest for the 500A2. The brown laminate CZ American stock and the .416 Rigby action for my 500 Mbogo.

My barrel is a 1:10" twist stainless McGowen of the same contour as used on the .505 Gibbs CZ rifles. It has a doughnut of steel for integral rear sight island and recoil lug to be machined by my smith. NECG banded front and rear sight insert. Barrel band sling base. Two cross bolts. Pillar bedding.

AHR will be involved with this one for safety, trigger, and bolt-handle-job, whenever my smith gets finished with his part. But I want to shoot it before I mail it off to Montana.

My smith is working on a second master's degree and awaiting admission to medical school, and I have several other projects for him to do before August 2008, I hope. I do not want to send anymore business his way, as he has enough on his hands. He did my previous 500A2 and .510JAB back around the turn of the millenium and did great work on them. He is one of two people in the country doing gunsmith work for a certain government agency, and nobody can do a better job of chambering a rifle than him.

Why not get AHR to do a 500A2 on your CZ? One stop smithing on that easy project.

10" or 12" twist? Surely not 15"!!!

perfect way to do it... send the who sheebang to go.. send it to anyone that knows how to build a bigbore...

now, of course, you can do a 550 magnum, if you really want a power house!!

you must put a recoil lug on the barrel, dual cross bolts and a wristpin.

jeffe

Thanks guys! I didn't realize that AHR would do a .500 A-Square.

Dave

AHR is reliable and will deliver. I suggest you consider a Integral muzzel brake with lots of small holes and counterbored about .010. I would strongly advise a 1:15 twist, but thats up to you. If you want to shoot A-max's then a 1:10 makes sense. Make sure the chamber is throated long enough for .50BMG bullets. Freebore is always a good thing from a pressure perspective. You'll need a barrelmounted recoil lug screwed and soldered to the barrel. AHR has a great trigger mod for the CZ and a nice three position safety. The gun will probably feed correctly even with the .416 Rig rails. A tiny amount of work and some polishing will make it amazing. AHR can do great stock work and checkering. Check their prices. Finally, you may want a 1/4 rib, sights, welded up bolthandle, a barrel band and nice Safari ramp front sights. I have no idea what it will cost,but it will work! You could always get a Mcmillan stock and crossbolt and bed it yourself. It isn't hard at all as another option.-Rob

......Bitterroot told me they would build me a 500 A-Sq. ...So I know they will.........Here,s how mine will be ,,,,,,I,ll have McGowan chamber a 1.5" outside diameter 1/12" twist .510 barrel in 500 A-Sq. with about a half inch of free bore ...The barrel will go onto a CZ550 Saf.mag. action that has been trued ....The rear sight base and 2nd recoil lug ,the sling eye and the front sight base/muzzel brake ,, all will be part of the barrel steel .......Just turn and mill away every thing that doesn,t look like the barrel I want .......The barrel will be Stainless steel that has been deep frozen .......It will probably go into an MPI stock as the one I have on my 416 is about perfect for me ........The stock will get a HiViz recoil pad or a KickEze.... CZ express rear sight , cause its the most Skookum .The front sight will have a CZ hood on with a small bolt holding it on ....The barrel will be 22 " long all told ....And have the whole thing CeraKoted kindof brownish , so it looks like an old hemlock limb .......

I've played with the 500A2 off and on for the last 7 years and still find no flies on it.

Very kind of Rob to acknowledge the 10" twist for 750-grain A-Max bullets in the 500A2.
Actually 12" twist is fast enough for that, so that the bullet revolutions-per-second are equivalent to a 50 BMG pushing the same bullet from a 15" twist at higher velocity.

But more twist is better in this case, and never a problem: go with 10" twist and it will handle any jacketed or monometal brass or copper bullet well. I have yet to find out about cast lead heavy gas checked slugs.

Those who made a 500A2 or a 50 Peacekeeper for mass consumption used a 10" twist. The A-Square loading manual data is for a 10" twist barrel of 26" length.

Throat:

The standard 500 A-Square throat is .5110" diameter, with .4000" length of parallel-sided freebore and a 1.5-degree leade.

This is more than enough for use of all the milsurp bullets. If you want to seat the 750-grain A-Max out as far as possible and still have the neck of the cartridge gripping all it can: 0.5667" freebore length. This will give all the COL possible and maximize case capacity.

I did just that long throat and accuracy did not suffer:




And on my only cowpasture outing with the 500A2, sitting on the ground with the long bipod extended, 16X Sightron mildot held some mils high for 540 yards, waiting for the wind to lull, I got lucky:





The discontinued low-height Warne QD lever rings with a 2.5X Leupold work great on the .510 JAB with 570-grainers at 2400 to 2500 fps. I switch that scope from the CZ .505 Gibbs to this BRNO ZKK 602, and rezero:


Ancient history.
Now I am starting to load cast bullets for plinking.
Thought I would get the off-the-shelf 500-grain Lee bullet mould for a 500-grain .515" FN boolitt and run it through the Lee .510" sizing die and lube it with alox only and see if it will plink.

GSC has a .510/450-grain HV that would make a nice deer bullet.

Or how about any off-the-shelf cast bullets good in the 500 Jeffery? .510 Wells? Sumbuddy who know?

www.customcastbullets.com wayne 535 fn or 600gr kinda rounded sp...(about a 2.5E) at 20-22b works great in the 500 jeffe, 510wells and 500 ar

El Jeffeoso,
Now you done it! I spied a "50cal. B.M.G. 775gr. F.N. G.C." that is .511" diameter and is 50-cents per boolitt!

I wonder how a 2100 fps load with this gas checked beauty would do in a 10" twist 500A2?
The 750-grain jacketed bullet (A-Max) is perfect at 2100 to 2200 fps in a 500A2.

It was designed for what velocity in a 50BMG?

.......Those 450 gr HV s will be absolutely perfect for my purposes .......20" barrel ,,should do 2750 fps no prob ....maybe 2800 ................KAAA BOOOOOOOMMMMMMM...........I bet I could shoot a bear in the ass and blow his f-----g head off.............................. YA..........................My Lott may have to become a donor for this ,, I know it won,t do that ..For some odd reason I would like to decapitate a big bear with a rifle ....... I guess I never really thot of it before .......An any angle ,,,any situation bear rifle ............I knew I could do that with my other 500. But the lighter bullets wern,t available for them ....I wasn,t too impressed with the integrity of the 450 gr 50/110 Barnes flat point but did do some blasting with them ...........

I'm saving those .510/450-grain HV's for the 500 Mbogo with a 25" barrel.
That should make 3000 fps.

That will be a fine "African Sheep Rifle."

I forsee a safari with a .395 Tatanka, and a 500 Mbogo ... and a .375 Weatherby as backup in case the ammo gets lost.

Any old .375 H&H factory ammo can be turned into a lower velocity super-killer by firing it in the .375 Weatherby chamber.

RIP- If you used a 1:15 YOU MIGHT HAVE SHOT BETTER AT 540 YRDS. Did you ever try it at 1000yrds? Show me the group! ALL the top .50BMG FCSA shooters use 1:15 with 750 Gr. A maxs. I've shot 4.25 inch 5 shot groups with a 1:15 twist. Never seen anyone with a 1:10 period. Guess why?
The .510/.600OK shot a 3 incher with a 1:15 and A-maxs. Certainly the shorter bullets used in hunting won't benefit at all from the faster twist. We have been over this before do I have to get my pipe wrench out again? !-Rob

........oh shit, here we go again.....

....guys, try decaf.....




KMule

Rob,
You recently recommended 10" twist for a 500A2 meant for shooting 750-grain A-Max bullets, didn't you?
What happened? Did you change your mind?
I agree that 15" twist is the cat's meow on a 50BMG with a long barrel. If I built a 50BMG with a 16" barrel, however, it would have to have a 10" twist for sure!

Farmer Brown's cow pasture does allow 942 yards on the diagonal. If I get a bulldozer to take out some trees and push up a berm on the adjoining property I may be able to extend it to 1000 yards. Correction on the hold-over: It was 5 mils at 942 yards the way I was sighted, and I was hitting in a two foot circle at that distance on a piece of cardboard propped against the fence, whenever the wind was not blowing too hard.

I did attend a 1000-yard match for 50BMG once. None of those guys would do it from sitting on the ground with a bipod. I need to build a concrete shooting bench in the cow pasture as soon as we annex the adjoining property.
Will let you know how the 10" twist does with 750-grain A-Maxes at 2150 fps MV, from a rifle that weighs 12.5 pounds with big scope and brake, someday.

Proposed new class of 1000-yard 50cal competition requirements:

1) Gun weight must be less than 13 pounds field ready, with scope, bipod, and muzzle brake allowed.

2) Must be fired from sitting or prone position on the ground, body armor allowed, but no snowmobile helmets allowed.

3) Must fire 700-grain or heavier bullet at greater than 2100 fps and remain supersonic past 1000 yards.

RIP- AT RENO we shoot Hunter class prone from the ground at 1000yrds off of bipods. I've seen some fantastic scores and groups shot that way too. Not much worse than from the bench.
Look You and I both Know 1:10 will work and if a guy was going to shoot just A-maxs from a .500a2 it will get the job done just as well. If you were going to shoot shorter bullets for hunting, I'd still go with a 1:15. Hunting after all is what the .500a2 was primarily designed for. It's just so versatile, thats what makes it great.
I'd love to shoot a match at 1000yrds with .500a2's, prone off of bipods. I'll bet the competition would be fierce.-Rob

Dave, im in the same process. originally, i thought of getting a montana PH action, but for that i have to wait till next fall, minimum. The CZ is the easiest and cheapest way to go, although these actions are rough and even after considerable elbow grease will never close up like a bank vault!
brockman makes a very nice laminated stock for the 550 mag, X10 nicer than the factory clunker.
im planning on a cz 550 action,brockman stock and a krieger or rock river barrel. The whole shebang should be under 2k. PM me for details; i have a great gunsmith, US mil armorer, sets up 408 chey tac and 50 BMG's for the sniper folks at fort bragg.

I've seen .500a2's on pre-64 Winchesters, Rem 700's( which I do not reccomend) and best of all a M30 Remington. All will work with various amounts of gunsmithing required. The CZ is nice because the .416 Bolt doesn't need to be opened up, and will work essentially out of the box as is. However, to make it slick you will need a new trigger and three position safety and have the bolt handle welded up. Mag box needs to be enlarged to fit the .500a2. Remember,you need a good barrel mounted recoil lug ( pse no welding), sights, muzzel brake etc. Make sure your gunsmith is very familiar with CZ barrel treads and has a lathe that can cut them. I square the receiver and the internal locking surfaces on my guns in addition.-Rob

And what about realoading dies and reamer? Prices, places and so on? If you have readily available info about these, I'd be happy to know. What to choose: A2, AHR, Mbogo, Whisper or 12,7x55 wildcat? I would be using Lapua's 338 LM brass or Norma's 416 Rigby.

the 510KX - fireform 416 rigby bases

the 500 mbogo - must use 3" rigby basic to have CORRECT cases, but rigby cases will work..

500 AR, fireform or die form and shorten 416 rigby or basic..

do NOT even bother trying to use lapua brss, it's too hard and short..

510wells/500a2 - fireform 416 or 460 weatherby brass

i am willing to send the 500 AR reamer to pacnor or mcgowen, if you want to use those barrels.. dies are $100 if you want a set from me. Brass, if you use hornady brass, is 30 bucks a box..

pacnor has 510wells and 500a2 reamers

otherwise you get your reloading dies from ch4d.com

Guys:

I have exchanged e-mail with Ed Plummer of AHR. They have a reamer for the .500 A-Square. They can re-barrel your .416 Rigby for you or make a new gun from scratch. For anyone looking for a .500 A-Square, I think that would indeed be the easiest way to go.

Dave

Dave