6.5-.300WSM loads

[Jase]

6.5x.300 RUM

Hi folks. I have built and worked up loads for various wildcats out of .300 and
.338 RUMs. I am currently working on loads for a 6.5 x .300 RUM. I discovered
after I had started that one can save some effort by starting out with 7mm RUMs. I started out with the slowest possible powders. Because I could find no
recipes for this case I began very cautiously and was rewarded with terribly low
velocities and very large fluctuations in velocity. Just as I was beginning to get
velocities up ( 37-3800 fps with 123 SMKs and 3600 fps with 142 SMK's ) I ran out of
8700 and have been unable to find more. I worked on RE-25 and got high pressure and pierced primers at around 3575 fps with the 142s. My gunsmith/friend
recommended 5010 and Retumbo. I have been working on these and H50BMG,
H1000, US869. Right now my best accuracy is coming with H1000, US869 and
H50BMG, with 869 the best. I am starting to get some moderately hard bolt lift at around 3550 fps with the 142s and 3700 fps with the 123s. I get occasional pierced primers 100fps after that.

I know that I will have short barrel life but I will live with that in exchange for
performance that sends 142 grain bullets out close to 4000 fps. As good or
better than .22-250s or .220 Swifts with 50 grainers! I can rechamber and
save some money that way before I have to buy a new Kreiger. I don't have
the numbers with me tonight, But I have fed the data into my Sierra ballistics
program and the ballistic curve looks as straight as a tight string compared to
6.5-06s and 6.5 Creedmores and all the other so-called hot numbers. They are still supersonic and have usable energy at incredible range. I was hoping
to get it all worked out before winter and cold weather comes to our range,
but that is not going to happen, I do not think-it is snowing right now! Bummer. I work at our range however and I may still get the loads ironed out.
I will post the data and some pictures if I can figure out how to work these
contraptions. If anyone has any help for me, including where I could get lots
of AA8700, please pass it along. I am also building a wildcat .338 that I am
hoping will get a real 3200-3500??? fps. One of my primary considerations is
the availability and cost of brass and bullets. However, the primary design
consideration is being able to use an off the shelf 700 reciever and bolt with minor modifications. I do not want to even consider custom $1000 recievers.

Thanks for listening.

 

[NCsmitty]

Jase, your barrel throat will be well worn by the time you develop your loads.
The original 7mm RUM shows around 3350fps with Maximum loads using 140gr bullets.
If you are actually achieving 3600fps with 6.5 142gr SMK bullets, you must be into a dangerous pressure area. Common sense should prevail.

Hodgdon H870 should work as well as AA8700 and be more available.


NCsmitty

 

[Jase]

6.5x.300/7mm RUM

Thanks NCSmitty for the advice. I know throat erosion will be rapid and I will

be backing off just enough to get out of dangerous pressure range. I am

finding that I can get a bit over 3500fps with 142 SMK's with 8700-8690-

5010 and maybe 50BMG without any discernible pressure signs. 3650 with

123 SMKs. I think I will have a few hundred rounds of life left in the barrel-I

am almost done with load development, at least for those two bullets.

I cannot find any 870 around here, but there is a lot of 869. Is that the

replacement for 870? Is it interchangeable with 870? Anyway, when

accuracy begins to drop off I will re-chamber it in an experiment to find out

whether the rest of the barrel is still unworn enough for accurate work and

for how many rounds. It may turn out to be very cost effective? I hope?

If not I will re-barrel and that will do it. I know the arguments against

pushing cartridges and guns to extremes, and I appreciate the argument in

favor of smaller, much more efficient and inexpensive and lower recoil

level cartridges. I really like plain old rounds, and use them myself, like the

.308and the .243.

On the other hand, I really like to experiment and learn, and I am looking

for a few really accurate, militarily useable, extreme range rounds. I like

my .50 BMG, but there are only a couple of places I can shoot it, so I am

working on a wildcat .338 that will push a 300 gr. SMK ( or hopefully a new

360 grainer? that Sierra is ? developing?) to perhaps 3200-3500 fps? We

shall see what we shall see. But 300 grain bullets at 3000fps have

substantial recoil, so that is the main impetus behind a smaller caliber, high

B.C. bullet. It has to have enough velocity to not only go long distances, but

also still have useful energy levels when it arrives.

Whew! That was long winded, but I hope it explains me a bit. I am not

really crazy or stupid. It's all fun...I love to shoot and hunt. Thanks for

listening and helping. Take care and shoot straight, Jase.

 

[NCsmitty]

Jase, here's hodgdon's burn rate chart. 869 is nearly the slowest on the chart.

www.hodgdon.com/burn-rate.html


NCsmitty

 

[Jase]

869

Thanks Smitty? (Do you go by Smitty?)

No wonder it does so well in my 32" Kreiger. I am going to concentrate on

that and see what kind of accuracy I can get. So far, looking mainly for

velocity, it has shot fairly well.

What kind of barrels do you believe are the most accurate?

What kind of glass do you like, dollar for dollar?

Do you have any special tricks for the receivers?


Thanks a bunch, Jase.