The 500 MDM is the largest of the B&M Series of big bore rifles. It is true .500 caliber, a full length 2.8 inch RUM case. It is designed for the Winchester M70 RUM action only. Winchester many years ago made a run of 300 Remington Ultra Mag rifles. Extensive modifications were done to the action to get the much larger case to work properly. One cannot take a standard long action Winchester and make it work with the 500 MDM, it must be a RUM action.
This cartridge was a long time coming, being on the drawing board for a couple of years. The original B&M thought was short, light, handy, fast to action, and powerful. The 500 MDM required a slightly longer action, and burning close to a 100 gr of powder I figured it had to have a longer barrel, true, but during the process we learned a lot about just how efficient .500 caliber is.
Brian at SSK, and I went around the block a few times about barrel length, and what it would take to make this work. I wanted 20 inches, he wanted 22 inches, and we ended up with a compromise of 21 inches in the beginning.
The first gun built was a high polish blue M70 21 inch barrel. It started out as a Super Grade, I wanted to use that stock. The first 18 rounds the stock busted all to hell........... Replaced that stock with another one, and it busted all to hell in the first 3 rounds. We were not even up to full power loads by any stretch...........
During this time we were researching for stocks and came across a small little known stock maker called Accurate Innovations in South Dakota at the time. What was attractive is the full length aluminum chassis they use in their wood stocks. After much discussion with the various owners at the time, we decided that the chassis would absorb the recoil produced by the 500 MDM and would work. The first stock done was a
very nice Myrtle Stock. They didn't have checkering per say, but laser engraving, so I elected for the laser engraving on the first gun with the Myrtle wood stock.
We finally got the gun put together and started some load development early in 2009. I also was using some CNC machined bullets that were designed by JD Jones and myself at the time. In particular a 510 gr Solid that was extremely successful in the 50 B&M and a 470 gr Copper Hollow point. Running the 510 Solid at 2300 fps and the 470 HP at 2450 fps, same POI at 50. I took these to Australia where it was a hammer on buffalo down under, and very impressive.........But this was only the beginning in the development of big bore bullet tech in which we embarked later for an entire line of new bullets from Cutting Edge Bullets and North Fork Technologies.
Concerning Accurate Innovations, Wes Chapman in Andrews NC, bought AI from the fellows in South Dakota. Wes and I worked very close, with him coming here for a week and going over the stocks I wanted for the entire B&M series rifles. Wes was younger at the time, and he has taken Accurate Innovations to what is now one of the Premium Stocks made in the US today. I would have nothing else, and yes, they will stand all the recoil you can send them and hold together. It is the only stock that will handle the 500 MDM period. We now use them for all our stock requirements, and Wes has all the specs required for each of the rifles.
The photo below has the first 500 MDMs made, the one in the middle is Gun #1 at the time. All these have 21 inch barrels, and you still see the laser engraving on the two bottom rifles. The top stainless/wood gun was #3 built, and has standard checkering, this stock was done one AI moved to Andrews NC. It is English Walnut. Of course you see the Myrtle Gun in the middle, and a standard Claro on the bottom.
Below is an old comparison to a Win M70 458 Lott that I used for years........
Again, a little nicer, newer photo of the English 500 MDM..............
n 2009 I took the 500 MDM out on its very first hunt, this was in Australia with Paul Truccolo, and was a real learning experience for both Paul and I. The 500 MDM struck down 13 buffalo, of my OWN, and a few of my hunting buddies buffalo as well. It really proved itself on this trip!
After the buffalo shooting we embarked on a mission to have even better bullets and more definite load data, which I am going to talk about in the next post.
Also, at a later date, I had Wes remove the laser engraving on the Myrtle Stock, shorten it a bit, to match its new shorter barrel at 19 inches. I also shortened the English gun to 19 inches.
But next, we will talk about Bullets and and Load data and just what the 500 MDM is capable of..........
This cartridge was a long time coming, being on the drawing board for a couple of years. The original B&M thought was short, light, handy, fast to action, and powerful. The 500 MDM required a slightly longer action, and burning close to a 100 gr of powder I figured it had to have a longer barrel, true, but during the process we learned a lot about just how efficient .500 caliber is.
Brian at SSK, and I went around the block a few times about barrel length, and what it would take to make this work. I wanted 20 inches, he wanted 22 inches, and we ended up with a compromise of 21 inches in the beginning.
The first gun built was a high polish blue M70 21 inch barrel. It started out as a Super Grade, I wanted to use that stock. The first 18 rounds the stock busted all to hell........... Replaced that stock with another one, and it busted all to hell in the first 3 rounds. We were not even up to full power loads by any stretch...........
During this time we were researching for stocks and came across a small little known stock maker called Accurate Innovations in South Dakota at the time. What was attractive is the full length aluminum chassis they use in their wood stocks. After much discussion with the various owners at the time, we decided that the chassis would absorb the recoil produced by the 500 MDM and would work. The first stock done was a
very nice Myrtle Stock. They didn't have checkering per say, but laser engraving, so I elected for the laser engraving on the first gun with the Myrtle wood stock.
We finally got the gun put together and started some load development early in 2009. I also was using some CNC machined bullets that were designed by JD Jones and myself at the time. In particular a 510 gr Solid that was extremely successful in the 50 B&M and a 470 gr Copper Hollow point. Running the 510 Solid at 2300 fps and the 470 HP at 2450 fps, same POI at 50. I took these to Australia where it was a hammer on buffalo down under, and very impressive.........But this was only the beginning in the development of big bore bullet tech in which we embarked later for an entire line of new bullets from Cutting Edge Bullets and North Fork Technologies.
Concerning Accurate Innovations, Wes Chapman in Andrews NC, bought AI from the fellows in South Dakota. Wes and I worked very close, with him coming here for a week and going over the stocks I wanted for the entire B&M series rifles. Wes was younger at the time, and he has taken Accurate Innovations to what is now one of the Premium Stocks made in the US today. I would have nothing else, and yes, they will stand all the recoil you can send them and hold together. It is the only stock that will handle the 500 MDM period. We now use them for all our stock requirements, and Wes has all the specs required for each of the rifles.
The photo below has the first 500 MDMs made, the one in the middle is Gun #1 at the time. All these have 21 inch barrels, and you still see the laser engraving on the two bottom rifles. The top stainless/wood gun was #3 built, and has standard checkering, this stock was done one AI moved to Andrews NC. It is English Walnut. Of course you see the Myrtle Gun in the middle, and a standard Claro on the bottom.
Below is an old comparison to a Win M70 458 Lott that I used for years........
Again, a little nicer, newer photo of the English 500 MDM..............
n 2009 I took the 500 MDM out on its very first hunt, this was in Australia with Paul Truccolo, and was a real learning experience for both Paul and I. The 500 MDM struck down 13 buffalo, of my OWN, and a few of my hunting buddies buffalo as well. It really proved itself on this trip!
After the buffalo shooting we embarked on a mission to have even better bullets and more definite load data, which I am going to talk about in the next post.
Also, at a later date, I had Wes remove the laser engraving on the Myrtle Stock, shorten it a bit, to match its new shorter barrel at 19 inches. I also shortened the English gun to 19 inches.
But next, we will talk about Bullets and and Load data and just what the 500 MDM is capable of..........