300 RUM Question

[Sekora]

I have been doing some load development with my Remington 700 BDL 300 RUM and 200 grain Accubonds. The rifle is stock except for a muzzlebrake. I have referenced several loading manuals and the max powder charge varies significantly. The max velocities all seem to be the same though, between 3050 and 3100. I am hitting this velocity around 89.5 grains with Retumbo where the Hodgen data says 95.5 grains is max. I know velocity is the deciding factor, as its related to the pressure, but I am also reading that a lot of guys are finding nodes over 3200fps with this bullet and not seeing pressure signs. My bolt is always a little sticky, so I can't go off of that, and I do not want to compromise my expensive brass by loading too hot. What approximately is the max pressure / velocity with a 200 grain Accubond in a 300 RUM?

 

[Rick300]

I have a 10 twist 26" barrel and I was getting 3250fps with 94 gr. of Retumbo. So.....I thought that was great and bought a couple more pounds - the next batch I blew primers and extremely hard bolt lift. I'm now at 90 gr. and 3197fps. The lot to lot variances drive me crazy, I just don't understand with today's technology why they can't be more consistent. You're going to have to test your lot and see what happens.

 

[Sekora]

Thanks. I found a node at 89.5 grains that shoots around .5 moa and is averaging 3080fps. Maybe I'll see what I can find working up to 3200. The lower node is consistent, but the window in powder charge seems to be small. I still have to test H1000 with this gun and got some N570 on the way from Midsouth. I am hoping to duplicate the consistency I already found, with a little more wiggle room in powder charge. If I can't, I know I have a good hunting load for this gun and bullet combo.

 

[Kurz]

My bolt is always a little sticky, so I can't go off of that

Please get your bolt fixed or retest your loads for less pressure. Safety above all things.

Comparing loads between shooters is a nearly impossible task. Barrels are different, powder lots are different, weather is different, altitude is different, the location of the lands, the diameter of the 'freebore is different, the shape and size of the chamber is different. You simply cannot control everything to expect the same data every time.

Each group that publishes reloading data has to be subjected to what powders and bullets are available. Then they have to depend upon the case manufacturers to get that formula right and the process of making those cases on a production line. We read each day where somebody doesn't like Winchester brass or someone thinks that only Lapua brass is the best. Neither these two or any other brand will demonstrate absolute integrity batch to batch because there are variations. Some get close but not absolute. That's why we test.

One of the weakest links to this testing is the chronograph. Yes I know, we all think that each and every model from every manufacturer is the most accurate but that's simply not true. Most of the simple chronographs are a clock timer reading a shadow passing between two screens. The sunlight or any form of illumination casting that shadow will change the reading depending on the quality and angle of the light. Even a $500 Labradar will give you disparate information if it's not aimed just right. Now compare this to a $90 economy chronograph.

Taken together, this is why we are encouraged to start low and work up slowly. Use those starting loads to establish your test base and move up the ladder until you are either satisfied with the accuracy or you feel a need to get a new powder or bullet.

Enjoy the process!

 

[ebb]

I don't think that the Retumbo problem is lot to lot changes. I had some loaded ammo that worked well here in south Florida in the heat of the summer. Took my reloading stuff and loaded ammo to my friends house in west Tennessee in the spring (much cooler) and the loaded ammo was over pressure. The ammo I made in Tenn had to be almost 2 grains lower to be a safe load. Both of these loads were from the same 8 lb jug of powder.

 

[Curmudgeon]

What brand is your expensive brass?

 

[Sekora]

The brass I have is Nosler. The bolt issue has been worked on, and has been improved drastically. It was a bad extractor. The bolt is still a little tight, but the gun is still fairly new. It is not as smooth as my trued action. I know this gun can use a little action work, but I do not want to put any more money into it as I really do not like a blued gun. It is going to be a western hunting gun when I am done with it and once I find the load for it, it will not be shot much.

 

[Homerange]

I have been doing some load development with my Remington 700 BDL 300 RUM and 200 grain Accubonds. The rifle is stock except for a muzzlebrake. I have referenced several loading manuals and the max powder charge varies significantly. The max velocities all seem to be the same though, between 3050 and 3100. I am hitting this velocity around 89.5 grains with Retumbo where the Hodgen data says 95.5 grains is max. I know velocity is the deciding factor, as its related to the pressure, but I am also reading that a lot of guys are finding nodes over 3200fps with this bullet and not seeing pressure signs. My bolt is always a little sticky, so I can't go off of that, and I do not want to compromise my expensive brass by loading too hot. What approximately is the max pressure / velocity with a 200 grain Accubond in a 300 RUM?

For a better understanding of the 300 RUM study this:
https://www.ballisticstudies.com/Knowledgebase/.300+Remington+Ultra+Magnum.html

 

[Sekora]

Good read. Thanks.

 

[ebb]

If I didn't have retumbo already I would be starting out with RL33

 

[Curmudgeon]

I shoot Remington brass. My rum buddy uses Nosler custom. He gets excess pressure when shooting max load. I don't. Find the volume difference with Nosler and other brass. I only know of Remington. I moved through retumbo and h 1000 till I started using us 869. I liked h1000 but now use only us 869. I now shoot Berger 230 hybrid. Started with 180 accubond went to 240 Sierra then Berger 230. This evolution with 31 inch barrel is very accurate. Cheers.

 

[ShootDots]

I have a 10 twist 26" barrel and I was getting 3250fps with 94 gr. of Retumbo. So.....I thought that was great and bought a couple more pounds - the next batch I blew primers and extremely hard bolt lift. I'm now at 90 gr. and 3197fps. The lot to lot variances drive me crazy, I just don't understand with today's technology why they can't be more consistent. You're going to have to test your lot and see what happens.

Your problem is a very common trait with Hodgdon powders. Their lot-to-lot consistency is somewhere between bad and horrible! I have NOT tried them out yet, however, the "new and improved" Viht line is SUPPOSED to be temp INsensitive! It is a well known fact that Viht powders are very consistent from one lot to the next. It might be worth your while to try out VV N570>>it's burn rate is similar to Retumbo.

 

[butchlambert]

A good friend of many years has built several 300RUMs. On his Shilen 27" barrel in 10 twist he uses the 210 Accubond and 89.5 of Retumbo for his best accuracy at 3100. His 200 grain bullets in a 27" Broughton barrel in 11 twist he uses 94.5 grn of Retumbo for 3275.
Kim has a bench set up at 800 yds from his feeder to shoot hogs. He very seldom misses.

 

[DUSTY NOGGIN]

kurz pretty much said it best,

if you are using wlr primers , you will see pressure sooner ( id recomend cci ), i recommend you do not go higher in charge weight it doesnt matter what others are getting to in theirs -- you will likely find and accuracy node at the 3050 range anyway

for what its worth my highest load using nos brass w/200ab retumbo wlrp was swiping brass at 89.5 . ended up at 88.8 ( .635 ) 3050 fps ... i now have a 92.5 retumbo load with cci's & remington brass


hodgdon also lists
Case: Remington
Twist: 1:10"
Primer: Remington 9 1/2M, Large Rifle Magnum
Barrel Length: 24"
Trim Length: 2.840"
Hodgdon
Retumbo
.308"
3.600"

you are using a different case , and length and primer ??? .. im betting you hear crunching at the 89.5 when seating???

make sure to never leave sizing wax on the cases, clean them well when shooting