Well, with the 338 AM in the hands of Fed Ex and on its way to get its final finish of teflon applied by Shawn C. I just received good news that the barrel for my next project will be arriving today.
Now my past Allen Mags have been designed for extreme performance big game hunting rifles. While they are extreme in performance I always wanted to keep them practical to use at least for the relatively experienced handloader as far as case forming and such things were concerned.
Well, my latest project is a little different. I really did not care on this one as it will be much more of a "need to have the biggest thing around" type of a rifle. I have shot the 50 BMG rifles for alot of years and they are alot of fun. Once you shoot a BMG its hard not to start pricing rifles and saving up.
Once you get into the big 50 more and more you realize that accuracy and consistancy can be extremely high quality in spite of the many handicaps facing the big 1/2" round.
I have always wanted to wildcat the 50 cal and several months ago, Richard Graves and myself were spending each others money again and came up with an idea, again a partnership between his bullets and my case design.
The 50 BMG round is generally loaded to 50,000 to 55,000 psi by todays bolt action shooters. At times even less then this with bench shooters. Our idea was to design a wildcat that would offer near 3000 fps velocity potential with a 750 gr bullet weight.
Better yet was that we wanted to shoot bullets in the 835 to 1000 gr bullet weights in this new design. This was as much a nessesity as it was a desire to try some heavier bullets. The reason is because of the wildcats case design.
The 510 Allen Mag has basically all the same case configuration as its much smaller siblings except a bit more body taper to counteract the huge baring surface for good extraction with high pressure loads.
Case capacity is estimated to increase by 45 to 50 gr of powder in the fireformed 510 AM case compared to the 50 BMG parent case.
Also, I designed the chamber quite tight for a 50 cal chamber to help allow the 510 AM to work at higher working chamber pressures. Nothing extreme here. There is no design to run this BMG case to 70,000 PSI but I do feel we can get into the 60 to 65,000 PSI range easily with the chamber design and case body design with no extraction issues.
What I really wanted was the ability to drive a 835 gr class ULD RBBT to the same velocities which are common with a 50 BMG bench rifle using a 750 gr A-max. Basically we are looking at a velocity of between 2500 fps and 2675 fps depending on how the handloader wants to load the 50 BMG. In all honesty, I want 2700 fps with an 835 gr bullet and I am hoping for 2400-2450 fps with a 1000 gr ULD RBBT if the twist will handle it.
When I started the project, I wanted to initially order in a McMillan BR single shot receiver along with a McMillan 50HBR stock for a rifle that would weight close to 50 lbs. THe more I thought about it though, the more I thought a lighter weight version would be much more practical for field use.
I wanted a full length bolt action receiver which could be fully accurized and used in a conventional manor. I had an LAR grizzly which was a great shooting rifle but the shellholder type receiver left a bit to be desired for shooting as it really slowed down the process and also required you to come off the rifle between each shot. I did not want this.
I really did not care about a repeating rifle as I am plenty used to single shots in the field. No disadvantage in my mind using a single shot.
I started looking at difference actions and complete rifles for donor actions and finally settled on the Armalite AR-50. I liked the way the receiver was designed although it was not the best looking receiver around it had the features I was looking for:
Full Length Bolt Action
Used Rem 700 trigger assemblies
3 lug bolt head
Other features I liked was the design of the receiver which is machined with a deep V on the bottom of the receiver which rides in a V-Block in the stock. Basically as close to a machine rest as you can get and still use a stock.
The receiver is very large. In fact it is one of the few receivers I know of and the only one I own that actually makes the 2"x10" BAT look on the small side!!! These two pics compare the AR to a LA Rem 700.
The receiver is a full 14" in length and its 2" in diameter measured on the octagon flats of its receiver.
The bolt of this receiver is just shy of 11.5" long itself and is a huge 1.375" in diameter. The bolt lugs are also this diameter.
The recoil lug fits right in with the receiver being a full 0.750" thick with a 1" deep foot.
The bolt is also fitted with a very large Sako style extractor for positive extraction of the big cases.
The AR receiver is actually much larger then it really needs to be for the 50 BMG cartridge. In fact it was designed for the much longer Russian version of the 50 cal military round.
When I heard the news that the barrel was coming I pulled the barrel from the AR-50 to inspect the receiver for truing. I was totally suprised when I measured the variance across the bolt face from the receiver face.
Three of the four measurements on the bolt face(12:00, 3:00, 6:00 and 9:00) were all within 0.0001" and the four measurement opened the variation up to only 0.0002" across the bolt face which is my limit for a receivers squareness.
I was also suprise to see the huge recoil lug was consistant in thickness to less then 0.0001".
Basically I decided the barrel was fit to build on as it set and as positive side note. If I ever decided to sell the rifle again, the new factory barrel could be reinstalled and get full market value for the rifle.
I am hoping to get working on the 510 Allen Mag assembly next weekend. Just wanted to update you on the start of another AM that will be released soon.
Again, this is a project in shear power at long range. Not the ultimate flat trajectory but shear HorsePower with Heavy bullet at long range.
More to come soon from this new monster!!!