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My T-REX Project - A 577 Tyrannosaur is Born - aka The Dinosaur Killer

Hello All,

I thought this might interest you so I brought it over from another post.

It was back in July of 2015 that I purchased 2 rifles from xausa (Bill), a fellow forum member here on AR. These rifles were built in the late 1970's by Bill and his partner, a then well know Custom Gunsmith named H.W.Creighton. All of the Creighton installed barrels are marked "CR" which stands for "Creighton Proof". Both rifles were chambered in a wildcat caliber developed and named by Bill as the 577 VSRE.

That stood for a .577 bullet used in a Very Short Range Express rifle.

Bill's 577 VSRE cartridge is based on a 577 Nitro Express case that is shortened to 2.500" with its rim rebated to .583" diameter, the same size diameter as a 460 Weatherby Magnum rim. Some 15 years later, upon the development of the 585 Nyati by Ross Seyfried, a variation of that same case, with a 2.787" case length and a .579" diameter rim, could be shortened by approximately 3/10 inches and used for the 577 VSRE cartridge without the laborious reworking of the head of a 577 Nitro Express case. Perhaps you could now call Bill's 577 VSRE, the 585 NYATI SHORT.

The whole purpose of Bill's 577 VSRE cartridge was to obtain the same ballistic performance of the 577 Nitro Express Double Rifle, except in a bolt action repeating rifle. That being 2050 fps with a 750g bullet.

The reason Bill built 2 rifles in the same 577 VSRE caliber was that the first rifle was a development rifle to work-up stock / barrel configuration. It was built on a P-14 Enfield action as a single shot. The brown stripe in the Laminated stock is a walnut spacer that was from various experimental dimensional changes that Bill tried during the rifles testing. The second rifle, the one actually intended for hunting, was built on a "G" series Winchester Model 70 push-feed action, as a repeating rifle. I've had a lot of fun with both of these rifles.

The 577 VSRE P-14 Enfield Single Shot. Modified Laminated stock - 12-1/2 pounds.

The 577 VSRE Winchester Mod 70 repeater. McMillan Stock - 12-1/4 pounds.

The Winchester was topped with a 4x24 Noske Scope #528 LER w/ Post in Weaver Rings & Bases.

What started this project was by an accidental discovery of a set of RCBS 577 T-REX dies on Ebay. The .577 Tyrannosaur or .577 T-Rex is a very large and extremely powerful rifle cartridge developed by A-Square in 1993 on request for professional guides in Zimbabwe who escort clients hunting dangerous game. The cartridge is designed for use in "stopping rifles" intended to stop the charge of dangerous game. The 577 contains a .585-inch diameter 750-grain Monolithic Solid Projectile which when fired moves at 2,460 ft/s producing 10,180 foot-pounds of force. This is perhaps the most powerful bolt action cartridge of all times.

While I was searching for a set of 500 Jeffery dies, I found the 577 T-REX dies. They were quickly purchased for less than 1/4th the current retail price.

My thinking was that that perhaps someday I'd find an original A-Square rifle in 577 T-REX caliber, and I'd already have the reloading dies. Well, with the dies now in hand, I set about searching for some brass, and found that AHR was offering the 577 T-REX brass at a very reasonable price. By week's end, I had the brass also.

After a month-long search for an original A-Square rifle in 577 T-Rex caliber, it occurred to me that I didn't need 2 rifles in 577 VSRE caliber. The P-14 single shot would be a good candidate for a make-over. Since the bore was the same, all that needed to be done was to re-chamber the rifle to the new cartridge, and modify the bolt face and extractor to fit. I decided to do it.

The first step in the project was to remove the barrel from the action. Fortunately, I have a Master Machinist / Gunsmith for a friend that had made a special barrel vise, and had a vast assortment of barrel and action bushings to go with it. He invited me to come over and use his tools.

The barrel was clamped in the vise with the appropriate barrel bushings.

Then the special split-bushing for the P-14 Enfield action was fitted to the action.

Next the action wrench was clamped over the bushing and tightened to the action.

Finally, a sharp rap with a lead hammer was all that was needed to spin the action loose from the barrel.

With a bushing selection like this, shown in the tool box, every type of action and barrel could be easily separated. There were even a few unfinished bushings in case a "special" needed to be made, as was the case for the custom barrel on this P-14 action.

With the action and barrel separated, it was now time to re-chamber the barrel. I had hoped to rent a chamber reamer for this "one-time" project, but I found no one had a 577 T-REX reamer to rent. After fruitless posts requesting to borrow or rent a reamer, or even to have someone do the re-chambering job for me, I was left with only one option; purchase a new reamer. But from who?

Searching the Gunsmithing Forums on several sites for chamber reamer sources, led me to Dave Manson, of Dave Manson Precision Reamers.

Dave Manson Precision Reamers
8200 Embury Road
Grand Blanc, MI 48439 USA
810-953-0732

Here is his Web Page address. Dave's Web Page contains a 32 page on-line catalog of not only reamers, but hundreds of precision gun related tools and gauges. Check it out.

https://mansonreamers.com/

I was absolutely amazed at the multitude of favorable comments that I found on various Gun related Internet Forums, complimenting Dave and his precision reamers. Comments like; ".. All of my reamers are from Dave Manson...", and "...Dave was very helpful, extremely knowledgeable, and responsive..." "...Reamers I have received are excellent and quickly made.." "..To sum it up, Manson is everything..."

It wasn't long before I was talking to Dave about purchasing a reamer. And yes, I have found all the above statements to be true. Dave Manson not only makes an excellent product, he offers personal service, and even offers an "expedited service" for AR Forum Members. And, he even has a rebate program.

Although standard delivery is 6 - 8 weeks, my 577 T-REX reamer arrived in a little over 3 weeks. It was professionally packaged in a slide-top "wooden" box. Wow! I haven't seen those since the 60's. I fully understand now why so many have given Dave so much praise.

Although I was lacking the large equipment for chambering, I have completed dozens of hand chambering projects over the years. Calibers as small as .14 up to as large as .700NE caliber. Here is the method I used. I mounted the barrel vertically in a vise over a catch pan.

I inserted an empty 577 VSRE case, into the existing chamber and measured the distance from the case head to the barrel end. This would be the same distance required for the 577 T-REX to head space correctly. Note: this measurement was only for an approximation as the actual final reaming is done by "feel" on an empty case to obtain exact head space.

To start the reaming, I plugged the bore with 2 squares of toilet paper about 1" beyond the pilot of the reamer, and then I filled it with oil. I carefully inserted the reamer and hand turned it a couple dozen times. I then removed it and cleaned it free of chips. I pushed the chip laden oil and toilet paper wad down through the barrel, and out the muzzle into the catch pan. I followed this with another clean wad, passing it through the barrel as well.

I then inserted an empty 577 T-REX factory case, and measured. I repeated this process by again plugging the barrel, inserting the reamer, and filling around it with oil. I reamed, cleaned and repeated this as many times as necessary until the chambering job was nearing my original measurement of the 577 VSRE case.

When I got close to the initial measurement. I screwed the action onto the barrel and tried to close the bolt on an empty 577 T-REX case. Note: the bolt was stripped bare so that neither the extractor, nor the firing pin assembly, would interfere with the "feel" of the bolt closure. As per plan, the bolt would NOT close. So, the reaming was repeated, but this time with only 2 or 3 turns of the reamer. And, again the action was screwed in place, and I tried to close the bolt on a Factory case. In this final "feel" for head space, I used a new case with each test to eliminate the possibility of a case shoulder being worked back from repeated testing. It took only 4 times to repeat this until I could close the bolt and ever-so-slightly "feel" the case in the new chamber. Perfect "minimum" head space was obtained.

Although this is a slow process, sometimes taking more than an hour, the results are excellent and worth the time. On this job, it took exactly 1 hour to re-cut the bolt face and re-shape the extractor for the new 577 T-REX case, and another hour to ream the chamber for the new case.

So, finally I have a 577 Tyrannosaur rifle, albeit NOT an A-Square Hannibal repeater. I left it a single shot, not wanting to deal with all the work to make it a repeater. And, since it is a single shot, I filled the mag box area with 1 pound of cerrosafe and added another 1/2 pound into the stock to bring the weight up to exactly 13 pounds, loaded. Nice thing about using Cerrosafe is; it weighs almost as much as lead, but has a very low mentling point of about 150 degrees, so it doesn't damage the wood when you melt it and pour it in. Also, its easy to heat it up and remove it later.

If the weather warms up a bit, I'll take my new Dinosaur Rifle it to the range for a test run, and post the results here.

This has been a real fun project.

And here's my final "2-cents" worth. I just couldn't resist.

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"You never pay too much for something, you only buy it too early."