New Mark X 30-06 throat

[brotherdarrell]

So, today I took possession of a Mark X minus the stock. It is in excellent condition and has a Timney trigger ($275 for those who are wondering). I got it home tonight and the first thing I did was do an impact slug of the end of the chamber and the throat. As I have come to expect I got a throat just a little bit different that what I had hoped for.

95295

There at the tip top you can just start to make out the beginning of the lands.[smilie=b: I put it right at .222" from the end of the chamber. I find that a tad looooong, but not the end of the world, right?

Ok, now for a few more dimensions. Start of the throat? .315" with a nice easy taper to the start of the grooves which appear to be just a hair over .308". It is hard to say as I didn't have enough lead down the throat to get a good impression.

So I check a few more dimensions. I grab a 311291 with its .2995" nose and stick it in the end of the barrel. I slides in with just a little wiggle room. I next grab an NOE 311407 which has a nose of .301" and repeat. This time the nose engraves nicely. I then take another and run it through my .301" Buckshot push through sizer and try again. The nose engraves, again, and when I get to the body (.3015") I can get it to enter with a little pressure.

So now I am scratching my head and check the next logical dimension. I trimmed my brass short so I could get a good diameter of the end of the chamber. .345"

All right, let think about this. My fired brass should have an inside diameter of approx. .345" - approx. .030" (brass neck total thickness) for a total of approx. .315". The start of the throat is .315". The throat is a little long but does end up at approx. .308". If I size a boolit with my .301" sizer the resulting boolit will fully engrave the rifling. I think I know what should work fairly well with this throat.

The question is how well will standard loobed boolits sized no larger than .312" work (that is my largest boolit)?

I really really hate throats. They give me headaches.

Darrell

oh yeah, the impact slug shows a chamber length of approx. 2.5". So all is not bad.

[Lonegun1894]

I used to have one of these, assuming this is the Interarms Mark X, and it shot great with the Lee 170FPGC sized to .311" and either 10.0 Unique or 16.5 of 2400. I don't remember the OAL anymore and can't find it in my notes. I traded it off for something I can't remember anymore. I wouldn't give up on it just yet, cause it just might surprise you.

[Larry Gibson]

Beautiful throat actually! Excellent for Loverin designed cast bullets. .311 would be a good sizing and the one I'd start with. I'd be searching high and low for a 311467 which should be the cat's meow for that. A 311466 should work quite well also. I had one of those many years back with a throat just like that.....traded it off before I knew what I know now about cast bullet shooting.

Larry Gibson

[brotherdarrell]

Larry - I have had throats that are much worse. My last '06 had a throat twice this long and it was polygonal to boot. This throat may be a little long but it is smooth as a babies back side. If I could rent a time machine for a couple hours I would own every Loverin design ever made, but for now I will have to content myself with the 311407 and 311465. My noe 311041 drops very close to .312" so it should work fairly well. My first thought when I saw this throat is that it should be a paper patch dream which is one of the main things I wanted to do with it.

So I can assume that .312" through a .315" throat at normal velocities should not be a problem and leave the hotter stuff for the PP. Now I just have to get it in a stock and do something about all the green I can see in the barrel.

Darrell

[Larry Gibson]

I think you've got it!

Larry Gibson