Shooters Forum banner
1 - 2 of 2 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Hi, I'm posting this problem in several forums where I've seen mention of the .260AAR - All Around Rifle (AKA 6.5 Jap Ackley Improved, 6.5-257 Ackley Improved, 6.5 AAR) and possibly others. The cartridge is formed from either .257 Roberts expanded to 6.5mm, and then fire formed in the chamber, or from 7x57 Mauser necked down to 6.5mm and fire formed.
The donor rifle is a BSA Monarch which is kind of a medium length action in that they came factory chambered in .243, .308, and 7x57. The stock is a real pretty piece of walnut, and I did a nice job with replacing the recoil pad, so it is a sweet looking rifle. The barrel is a 6.5mm Shilen.
My problem is this: The gun smith who did the work appears to have run the reamer in *way* too deep. This was probably the last rifle he ever built, as he was having more and more health issues, and as it was, it took three years for him to finish it, with a lot of "encouragement" at the end. The dummy cartridge he sent along as a sample measures 2.94 OAL (I know I should measure to the ogive, but I needed to get a rough idea of how much trouble I am in). I could not seem to seat any 6.5 bullets I have out far enough to touch the lands, so I devised a way to measure the OAL of a "hypothetical cartridge" with a bullet touching the lands.
I first put a .25 dia. aluminum rod down the barrel until it rested on the closed bolt face, and marked the end of the barrel using a knife blade. Then I chambered the sample cartridge and did the same. Finally, I dropped a 6.5 bullet into the chamber and put a spring into an empty case so that I got spring tension on the bullet holding it into the lands as I closed the bolt. Again, I marked the rod.
The results are that the sample cartridge measures 2.94 inches OAL, and the OAL of a hypothetical cartridge with bullet touching the lands would be 3.68 inches (.74 inches too deep). In other words, I cannot possibly make a cartridge for my rifle.
As I said, the rifle maker is really out of the picture at this point. If I save this rifle, it will be by having someone else fix the problem.
The barrel is also too long (my fault -- I thought 25 inches would give me max velocity, but to tell the truth, it is out of proportion in the factory stock), and anyway it came out 25.5 inches. This gives me the opportunity to shorten the barrel from either or both ends and still end up with a 23 inch barrel, which is a length I happen to like.
So, I am looking for suggestions. Do you all think the barrel can be salvaged, realizing that somewhere around .74 inches has to come off the chamber end? Shall I have a rifle maker open it up to 6.5-06 and see if it can be rethreaded to my Sears model 53 (a Win. Model 70 clone?)
I'm up for nearly anything that will salvage the barrel, including putting the original .243 barrel back on and putting the 6.5mm tube on something else.
If any of you have a .260 AAR, could you measure the OAL (or length to ogive - just note which) so I can get an idea of just how much too long my chamber was cut? I also have some Cerrotex coming in the next few days so I will soon have an accurate chamber cast.
Thanks in advance!
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #6 · (Edited)
Thanks for all the clarifying questions, everyone! Since this is a wildcat round with an Ackley Improved shoulder, I essentially control the headspace, and in fact, with the new questions, I can say that the headspace is fine. Running 7x57 brass into the .260AAR die, a little at a time, results in the brass snugly chambered right about where I expected them. So, it is the leade that is almost .75 longer than I expected. I was not aware that some cartridge families have a long freebore -- I have never (knowingly) loaded with more than about .100 freebore, thinking that having the bullet get too much of a jump before it hits the rifling would cause dangerous pressure spikes.

So.... If a 130 grain 6.5mm bullet freebores for .700 or so (I do need to cast that chamber!) before it engages the rifling and leaves the muzzle at a bit under 3000 fps, in general, am I going to be OK?

Thanks again -- I am going to be away this weekend and may not get to casting the chamber until next week. In the meantime, I am not quite as concerned as I was, and for that I thank you all and will report back on the chamber measurements ASAP.

-T
 
1 - 2 of 2 Posts
Top