I am looking at picking up a used Ruger M77 Magnum in 416 Rigby. This is an older rifle with the large diameter muzzle. I really am interested in getting it converted to a larger caliber. I also like the looks of the factory barrel so I want to keep it.

Who would you all recommend to perform a conversion on this rifle from the current 416 Rigby to 500 A Square. Remember I want to keep the barrel so it will need to be rebored.

Thanks,
Casey

Hi Casey,
Your looking at the same process that I went through to build my first 470 Mbogo. Try to contact Cliff LaBounty in Washington for the reboring unless you know of someone that has a good track record with Ruger barrels. The one Cliff did worked out great but I had another one done by another company and they destroyed the barrel. Once it is bored out to 50 caliber you may have to put a couple of hidden cross bolts in your stock. I would recomend that you remove a small amount of material ahead of your magazine box and glass bed the front of the box so it can't be driven forward under recoil with shells in the box. You will notice that the underside of the barrel has a small tab that holds the magazine box in line and it will definitely bend in and screw up your feeding. It happened with mine and with the 500 A-Square it will happen to you. With the 500 you may have to modify the feed ramp also. You will probably want to change the recoil pad also. The 500 is a kicker. Good luck with your project.

470 Mbogo

You may want to give Harry at McGoven a call as he got a 500 A-Square reamer. I am not sure if he does reboring though. It does not hurt to check. Good luck.

You may want to consider this before you build yourself a 500 A2.

I have one. The recoil generated by this rifle will push the bullets into the cases in all the rounds in your magazine. Since the bullets are crimped in place, the recoil pushing the bullets into the cases causes the case mouths to bulge out BADLY. My rifle will frequently not chamber the third round, and almost never chamber the fourth round.

I also strongly recommend if you build one that you stock it in a McMillan composite. My rifle is an original Hannibal. After blowing up, literally, the factory wood stock I went to a modified McMillan. It only took 15 rounds to destroy that A Square stock by the way. Most impressive!

I suspect the problem is that those 500 A2 rifles weigh only about 10.5 pounds and therefore generate liberal amounts of recoil.

A couple more pounds of steel or mercury in them and it should take the edge off the recoil and hopefully keep the bullets from plunging down into the case.

Just an opinion...