6.5x55 at modern pressures

[Freyr_255]

Hey just wondering if anyone has loading data for the 6.5x55 in a modern action that can take 60k-65k psi -ish loadings? I've read about some books having load data for the old mauser 96's and modern actions but all my loading books and references just have normal loads at 50k psi.

Looking for data using H4350 and 129gr SST's and also data for 120gr and 140gr jacketed bullets if available.

As a part II if anyone has loaded up this cartridge to modern pressures, about what % above max loading are you running at to achieve this? Don't need exact info just trying to get a rough idea of how high above standard book loadings I can/should go.

 

[Dunk]

Well I will tell you about my recent experience with 6.5x55 pressures. I had a 96 6.5x55. I used a moderate load of IMR4350 Hornady 140 SST in it with no pressure signs. I looked for and found a 98 mauser thinking I could up the pressures a bit. I used my loads from my 96 in the 98 . I could hardly lift the bolt handle,primer very flat. So just because you have a strong action,proceed with caution.

 

[Eagleye]

Yes, be careful when trying a strong, modern action.
Don't "jump" at top loads, start low and work up carefully.
I have a M700 Classic in 6.5x55....it is on it's 3rd barrel. [Do you think it gets shot a lot? lol]
I like the 125 partition for deer-sized game, and the 140 Partition for moose.
It is entirely possible to reach 3000+ with the 125, and 2850 or so with the 140, using Norma MRP, or RL 22.
IMR 7828 will also get top velocities, as will Vihtavuori N165.
Regards, Eagleye.

 

[Cleftwynd]

Dunk, there could also be quite a difference in the chamber, freebore/throat between the two rifles, a different seating depth could possibly reveal that the 98 will take the same load, or more. Just a thought...

 

[Dunk]

Dunk, there could also be quite a difference in the chamber, freebore/throat between the two rifles, a different seating depth could possibly reveal that the 98 will take the same load, or more. Just a thought...

Yes, thanks. These are some of the reasons to proceed with caution.

 

[Freyr_255]

Yes, be careful when trying a strong, modern action.
Don't "jump" at top loads, start low and work up carefully.
I have a M700 Classic in 6.5x55....it is on it's 3rd barrel. [Do you think it gets shot a lot? lol]
I like the 125 partition for deer-sized game, and the 140 Partition for moose.
It is entirely possible to reach 3000+ with the 125, and 2850 or so with the 140, using Norma MRP, or RL 22.
IMR 7828 will also get top velocities, as will Vihtavuori N165.
Regards, Eagleye.

First question is how are you fitting in enough of the slower burning powders in the case? Seems to me that you'd be getting to the point of overflowing fairly quick. Question #2: what length of barrel are you running? I'm using a 24" barrel and figured if I tried to go with too slow of a powder I'd run into issues of not getting a complete burn.(and let's face it...my powder choice is mostly because I have it and selection in town is garbage/unreliable)

And since it was brought up...what are people's recommendations on seating depth for higher pressure loadings? Do you gain more by seating closer to the lands thereby expanding case volume or does extra jump in there help regulate pressure?(thinking like the long throats on weatherby chamberings)

 

[stubblejumper]

My Tikka T-3 Varmint likes R-22 behind the 142gr matchking. Velocity is right around 2750fps, and the load shoots sub 1/2moa for five shots. Due to the boattail design of the bullets, I have to limit my COL to allow enough bullet shank in the case to provide proper neck tension. This results in a fair jump to the lands, but it doesn't seem to effect accuracy much. and the loaded rounds will fit the magazine.

 

[Goldenlakepete]

In the Lyman #47 Loading Manual there is a load listed for a 120 gr bullet and 49 grs of H380. I don't know if this is a misprint or not but I started at 44 grs which was OK, went up to 47 grs which was too hot. The bolt was difficult to lift and the primers were cratered. Lousy accuracy too.

I settled on 44.2 grs of H380 which is a very accurate load and drops deer quickly.

This is in my Model 70 Winchester Featherweight.

 

[OldDude]

I seem to recall seeing / reading about ammo designated as 6.5 x 55 SKAN, along with a caution not to use it in rifles chambered for 6.5 x 55.... Supposedly, it's loaded to higher pressure levels for modern firearms.... Now that I think about it, the caution may have been for load data.

A quick Google search turns up a post indicating it's also longer than 6.5 x 55.

But I could be hallucinating... ;-})

 

[paperslayer]

at 60-65 K it is not likely the action that will not take the load, but the case itself. I run a very stout load of RL17 in mine with 140's and I am about 60K. I am definitely in the yellow, but it bug holes 140 hunting VLDs at that velocity.

 

[Freyr_255]

My Tikka T-3 Varmint likes R-22 behind the 142gr matchking. Velocity is right around 2750fps, and the load shoots sub 1/2moa for five shots. Due to the boattail design of the bullets, I have to limit my COL to allow enough bullet shank in the case to provide proper neck tension. This results in a fair jump to the lands, but it doesn't seem to effect accuracy much. and the loaded rounds will fit the magazine.

Ya I noticed having to do this as well with the 129gr SST's I loaded up here. I have them running at about 3.1 COAL just to keep the bullet fully in the neck of the cartridge. Actually looking at it I should almost bring them back to 3.05". Ah well I'm sure they'll stay in the case with no issue.

I ended up loading up rounds from 44.5-49.5gr of H4350 behind those 129gr SST's(book max is 45.5). We'll see how it goes and I might have to do a round II of development(limited due to only having one 50rd box for them ATM). Hopefully the forecast is right and I'll have a chance to shoot them this weekend. Supposed to be a balmy -6 out on sunday. Might have to go dig out a t-shirt or something....

 

[Pathfinder]

First question is how are you fitting in enough of the slower burning powders in the case? Seems to me that you'd be getting to the point of overflowing fairly quick. Question #2: what length of barrel are you running? I'm using a 24" barrel and figured if I tried to go with too slow of a powder I'd run into issues of not getting a complete burn.(and let's face it...my powder choice is mostly because I have it and selection in town is garbage/unreliable)

And since it was brought up...what are people's recommendations on seating depth for higher pressure loadings? Do you gain more by seating closer to the lands thereby expanding case volume or does extra jump in there help regulate pressure?(thinking like the long throats on weatherby chamberings)

A- you will run into pressure issues before you run out of space with the slow powders that are best in this case (like R-22) 4350's should be fine.
B- Yes, seat the bullets out longer and you gain powder space, depending on the gun you can be limited by the magazine...not so on my Tikka M-65. Not sure what gun you are loading for.

 

[burnt_servo]

i'm surprised no one has mentioned this yet .....

what about the case taper ?

how many modern cases are there , loaded to over 60,000 psi ...... heck even loaded to over 50,000 psi , with a similar case taper to the 6.5x55 ?

with the fairly significant case taper you are going to get a lot more back thrust against the bolt as you raise the chamber pressures ......

my first thought would be to ream the chamber out to a ackley version ( or similar ) first before trying to load it to modern pressures.

 

[kayaker1]

i'm surprised no one has mentioned this yet .....

what about the case taper ?

how many modern cases are there , loaded to over 60,000 psi ...... heck even loaded to over 50,000 psi , with a similar case taper to the 6.5x55 ?

with the fairly significant case taper you are going to get a lot more back thrust against the bolt as you raise the chamber pressures ......

Both the .300 H&H and .375H&H have a lot of taper and both have a MAP of 62KPSI, and a larger case head area than the 6.5x55.

Max loads for the 6.5x55 in some manuals are very very mild, others make full use of the 51KPSI SAAMI MAP (Hornady and Alliant data are very mild, Lyman, Barnes No3 and Lee run a little hotter, for example), so 'book max' for the 6.5x55 varies greatly depending on the source.

I dont feel the need to turn my 6.5 into a .270. If I can get 120's at 2800-2850, 130's at 2700-2750 and 140's at 2600 all with good accuracy, I am happy! (these are not difficult to reach either).