6.5 x 57 Mauser Improved??

[RickB]

One other thing. Please check your seating depth closely. I can only speak from my experience, but I have encountered pressure signs with heavier bullets before achieving the velocity window I desired if the bullet was seated in the lands or too close to them. I like to keep the bullet around 0.010" to 0.012" off the lands both for pressure reasons and in case I get caught with a round in the chamber and have to remove it...spilled powder in the action is such a delight,not!).

With a regular .260 Rem I have been able to reach 2825 fps with 139/142 grain bullets,moly'd) in 26 to 27 inch barrels using Rel 19 or H4350. As they say, your mileage may vary so please continue to be careful.

Cheers

 

[montanaearl]

steve, i am building a 260AI and am curious about what your reamer specs were. I have a JGS designated 6.5-08AI which has 0.050" freebore. Is that what you have, and if so, did you consider throating your chamber. The main reason I ask is that I am using a surplus Mod70 long action from another gun, thinking that I could run the bullets further out without being limited by magazine length.

 

[SteveLC]

I don't remember the freebore spec on the reamer offhand. I'd have to ask the 'smith about it. I am able to use the magazine with the 120 Noslers and still reach the lands, and I know it is a .297 neck. I will try coming back off the lands .010 and see if it likes that. I'm in process of prepping some Lapua 308 brass I had in the cabinet to use in it. 5 bushing stages gets it to size. Then I'll need to turn necks, and will try to get a little off the shoulder now to reduce donuts later. With the bushing sizing, I've left a little at the neck/shoulder junction unsized that I'll thin first with the turner. Next step is to get neck thickness down to .015. After sizing the 308 necks are at .022". I hope the extra step will help with the donuts. I'm only going to the trouble because the R-P brass I was using is kinda spooky to me now. As mentioned they were failing, and it got mixed when I spilled the ammo box, so not sure which pieces were over-stressed. I will post after I get some fireforming done, and do some load tests.

Steve

 

[RickB]

I don't remember the freebore spec on the reamer offhand. I'd have to ask the 'smith about it. I am able to use the magazine with the 120 Noslers and still reach the lands, and I know it is a .297 neck. I will try coming back off the lands .010 and see if it likes that. I'm in process of prepping some Lapua 308 brass I had in the cabinet to use in it. 5 bushing stages gets it to size. Then I'll need to turn necks, and will try to get a little off the shoulder now to reduce donuts later. With the bushing sizing, I've left a little at the neck/shoulder junction unsized that I'll thin first with the turner. Next step is to get neck thickness down to .015. After sizing the 308 necks are at .022". I hope the extra step will help with the donuts. I'm only going to the trouble because the R-P brass I was using is kinda spooky to me now. As mentioned they were failing, and it got mixed when I spilled the ammo box, so not sure which pieces were over-stressed. I will post after I get some fireforming done, and do some load tests.

Steve

Steve,

I would suggest running the .308 Win cases through a 7-08 Rem Sizer. At that point you can turn the neck and then size it to something appropriate for the .260 Rem. With a ).297" chamber neck something around 0.294" loaded neck OD should work well.,I have a 0.297" neck on most of my chambers.) Unless you just really are committed to a "tight neck",high maintenance) 0.294" loaded OD is plenty tight enough in my opinion for most any application short of a full out BR rig and helps avoid some of the problems of a tight neck when shooting in the real world.

By turning the case necks while at 7mm a portion of what was the neck will wind up in the shoulder and help to avoid the formation of the infamous "donut" at the neck/shoulder junction. The case neck should not get a great deal thicker when necked down from 7mm to 6.5mm, but you should try a few to arrive at the final settings for your neck turner. You may want to consider whether you should anneal the case necks somewhere in this process. If you decide to anneal the case necks, be careful not to overdo it as it is surprisingly easy to "kill" the brass by heating it until it is cherry red.

Good Luck,

Rick

 

[sambubba]

Steve, I have a .260AAR,6.5x257AI)that I have been doing the initial load work-up on during the last month. I have not tried the 123g, but have used the 100g NP and BT, 120NBT, 129 and 140g Hornady, and the 130g TSX. I have achieved 3256 fps with the 100's, 3040 with the 120's, 3000 with the 129's and 2854 with the 140's out of a 23" barrel using W/W brass and Federal 210 primers. I had to back off the velocities/maximum loads listed above due to excess pressure. My safe loads for trouble
free hunting ran 3256 for the 100's, 3000 for the 120's, 2925 for the 129's and 2800 for the 140's. My barrel may be a little "slow" based on correspondence with others who shoot this round. I think 3300 for the 120's even with a 28" bbl. is not achievable w/o excess pressure. I also have two 6.5 Swede's and a 6.5-284. My .260AAR runs about what my 26" barreled MRC rifle does. It is very accurate and will make a dandy hunting round.
One thing I forgot to say is my reamer was made by Dave Kiff at Pacific Tool and Grinding ordered through Midway for 95.99.

 

[SteveLC]

Thanks again for the input guys. I am intending to move forward with the 6.5x57 project and will build this rifle on a B model Bat action and a McMillan stock to shoot medium to long range benchrest. Probably be next year before I have it ready. BTW, my 308 Lapua brass to 260 turned out very nice, with the neckturning ending up in the shoulder. I intend to fireform them, and already have a few to make sure the brass was not too hard. My finished diameter is .2935 on a loaded round. I do plan to anneal before I use them again. I may ping some of you if I run into problems.

Steve