Help! 300RUM load problems

[RDM416]

I just bought a new 300rum sendero and have been working up loads for it. I have tried both the Barnes 168grn TSX and the 165gr Swift Scirrocco.

The problem I seem to be having is that I am seeing ejector pin shiny spots on the case heads (slight ones, not raised).
I am seeing this over pressure sign at less than the max load listed by the manual and my velocities are way below the book too.

I have tried RL25, RL22, and H1000. I seem to top out 1 to 2 grains below max listed load, but with less than speed than the manual states.......example: RL25 94gr, Barnes 168gr TSX gives me 3240fps with the above mentioned over pressure sign. The manual lists 94gr as the max load, with a speed of 3448, I'm 200fps below that!

By the way I am using an Oehler chrony with 3 skyscreens so it should not be the chrony.......

That example seems to hold true for the other loads I have tested.....I am running 150fps to 250fps below published velocities.

Long post, I know, but I had to explain the problem. Any ideas or explanations from you 300RUM experts out there would be greatly appreciated

 

[Sasquatch]

Are you doing your testing in extreme heat? higher elevation? seeting the bullet too close to the lands of the rifling? is your barrell the same length as the test barrell?

It also might just be your particular rifle. Using the 180 Gr. sciroco and premier ultra mag factory loads are both over pressure in my RUM, but I can get no signs of over pressure using Retumbo in my 26" factory tube. my most accurate load was 1 grain below max in the hornady manual.

 

[RDM416]

Thanks for your comments. It is hot here, but I have been doing my testing in the mornings so it is only around 75-80F. The rifle has a 26" factory barrel.

The bullets are not close to the lands, further back than I want actually. I had to seat them pretty far back to get them to fit in the magazine.

Have not tried Retumbo yet. I'll work up some loads with it today and see how that goes.

 

[royinidaho]

I've been concerned about the same indications in a BDL 338 Win Mag. Other than the slight shiney spot and resulting bolt face burnish all other case measurements are well within reason.

I am satisified that pressures are not excessive but are are towards the top end.

Another thing to consider is bullet bearing surface and seating depth. Also there may be a condition with the barrel that results in lower than expected velocity for a given powder weight. Primers make a difference also.

Each rifle is unique.

Sounds like you are doing the right things.

 

[REV]

I'm starting to see a pattern here... My 300 RUM has a hard bolt lift using the factory ammo. 180 gr swifts and 200 nosler partitions (grant you it is 98 freaking degrees when I shot it.)

 

[kraky2]

Sometimes excessive headspace can cause pressure indicators. When you guys resize your brass do you have the sizing die set so it only has .003-.005" headspace? I loaded for a guy with a winchester rifle in 300 wby--that gun was "growing the brass" .030" on the first firing. I had to stay well under max loads till I resized and had the brass more set to his chamber. Then I could bump up the loads and not see pressure indications.

 

[Jon A]

There's no way you're getting pressure signs at that velocity. I've shot both the 180 TSX and Scirocco from my RUM nearly 100 fps faster than you're shooting the 168's and that was just a "starting load."

I'd look for other things--headspace, rough face on ejector/weak ejector spring, etc.