300 rum load development

DoubleGobble00 said:

Yeah I agree that the velocity and group looked best with 87-88.5. I was planning to reloading a few sets of 3 in this range or do 87, 87.2, 87.4, etc mini ladder test.

I was just expecting more velocity before pressure. I have some H1000 I could try or just buy some RE33 or Retumbo

Click to expand...

Retumbo!!!!!

If you get ejector marks on everything including low pressure and factory rounds it's likely just a characteristic if the rifle itself. If you dont have a sticky bolt I wouldn't be concerned with it. Primer craters can show up on alot of magnum cartridges even without high pressure. Could also be because the hole for the firing pin to come thru the bolt face is slightly larger than necessary or the firing pin is protruding deeper into the primer than necessary causing the primer body to get thinner than normal. If it's not extreme and you're not blowing primers I wouldn't worry.

Find your high pressure drop a grain or so then play with your seating depth on the bullet since bergers are seating depth sensitive. Once you get a great group, if you really want to you can test for your high pressure threshold again to see if you gain or lost any ground and take your charge to a safe level. May need to tweak your seating depth a little after doing that but not always.

GOBBLE00 ~
I wish I had the skill and the 230s to tune.
For dialing in a new scope or built you might play and burn some of these.
This low budget combo works and is amazingly forgiving on most every 300 Rum.
200 grain Accubond 2nds and Retumbo. Simple, Cheap, meat.
Great posts, Thank you.

Since you have a 29" tube if you have the h1000 on hand I would try that first. Before spending$ on more powder.It may be a winner the long tube.

Berger 230gr Hybrids and 89.4gr of retumbo have worked great for me. Here is a link to my load development adventure, I'm no pro but maybe it can be useful:

https://www.longrangehunting.com/threads/300rum-230-berger-ladder-test.127800/

DoubleGobble00 said:

I shot my first rounds of hand loads this weekend for my 300 Rum. I loaded the following:

Nosler brass (first 5 new brass, others 1x fired)

215 M primers
Imr 8133 (88.5 to 91 grains)
Berger 230
Neck size only

The 89.5 and 91 loads had primer cratering bad. All shots had ejector marks and slight crater. I'm thinking my headspace is too tight that could cause this? My brass is pretty tight when chambering. All my factory ammo shows ejector marks also. I was hoping to get more velocity since I have 29" barrel.

On separate note, which do you think I should start next steps of load development? Also, if I full length size could I get more velocity and lower pressure?

Thanks,

DoubleG

Click to expand...

You

DoubleGobble00 said:

I shot my first rounds of hand loads this weekend for my 300 Rum. I loaded the following:

Nosler brass (first 5 new brass, others 1x fired)

215 M primers
Imr 8133 (88.5 to 91 grains)
Berger 230
Neck size only

The 89.5 and 91 loads had primer cratering bad. All shots had ejector marks and slight crater. I'm thinking my headspace is too tight that could cause this? My brass is pretty tight when chambering. All my factory ammo shows ejector marks also. I was hoping to get more velocity since I have 29" barrel.

On separate note, which do you think I should start next steps of load development? Also, if I full length size could I get more velocity and lower pressure?

Thanks,

DoubleG

Click to expand...

I have good luck with H1000 77.1 great. 2765 26" barrel

How many total rounds do you have down the barrel? A factory barrel (after being broken in) will see an increase in velocity with each shot fired with the same load until approx. 30-40 rounds are down the barrel. At that time, you will hit the plateau where the carbon fouling arrives at equilibrium. I have found it only takes about 10-20 rounds in a custom barrel. No point in doing any kind of tests for max velocity or ladder test until this is achieved.

Secondly, are you absolutely sure it is the brass that is making it difficult to close your bolt on a loaded round? Sometimes, we unwittingly are camming the bullet ogive into the lands ever so slightly thereby creating pressure higher than normal.

Just a couple of things to check before you start pulling your hair out. I ended up using RL33 in my 300 RUM with the 230 gr. Berger. Just a little better velocity than Retumbo (also a great powder). Unlike the other Reloader powders, RL33 seems to be very temp insensitive.

azsugarbear said:

How many total rounds do you have down the barrel? A factory barrel (after being broken in) will see an increase in velocity with each shot fired with the same load until approx. 30-40 rounds are down the barrel. At that time, you will hit the plateau where the carbon fouling arrives at equilibrium. I have found it only takes about 10-20 rounds in a custom barrel. No point in doing any kind of tests for max velocity or ladder test until this is achieved.

Secondly, are you absolutely sure it is the brass that is making it difficult to close your bolt on a loaded round? Sometimes, we unwittingly are camming the bullet ogive into the lands ever so slightly thereby creating pressure higher than normal.

Just a couple of things to check before you start pulling your hair out. I ended up using RL33 in my 300 RUM with the 230 gr. Berger. Just a little better velocity than Retumbo (also a great powder). Unlike the other Reloader powders, RL33 seems to be very temp insensitive.

Click to expand...

What was your load/velocity/barrel length. I have never used rl33 but I'm curious and it may benefit the OP.

Mileage will vary, so use with caution. I'm using 94 gr. of RL33 with the 230 gr. Berger OTM Hybrid. Seeing just over 3,020 fps in a 28" barrel. No pressure signs, but very close to a max load for my rifle. Close to 400 rounds down the tune at this point.

I will probably be backing down to 92 grains (est. 2,950 fps), just to save on barrel wear and tear. I found nodes at both at 92 and 94 grains with RL33.

For 210 & 215s, I actually use H1000 and get right at 3110fps with both. And very accurate as well. I have a light load of 85.5gr @ 2965fps for kids, and a full power.load @ 90.1gr @ 3110.

But I rarely use the 215s @ 3110 anymore because I get the 230s going the same speed.

First unless the brass was fired in that rifle, you should full-length size it. Neck-size only if/when that brass is staying exclusively with that launcher, otherwise you are creating potential for pressure signs. Granted some of those signs MIGHT be false readings if the bolt is hard to close, but IMO this is not the caliber to get too frisky with!

Second, yep you probably have either pressure issues or a bad fit in the chamber...head spacing? Better back off that load by reducing powder charges. In this cartridge, I have no doubt you can tighten that group up but if those primers keep doing that I recommend a trip to a gunsmith for a check on your headspace. Also - make sure that chamber is REALLY getting cleaned all the way. At typical RUM pressures it doesn't take much "varnish" build-up in the chamber to start screwing with your headspace, and then reading pressure signs gets tricky.

Third, a question - what other bullets/bullet weights are you planning to try with this rifle? I have not spent time with the 230 bergers in this cartridge, but would like to share this thought - decent 190-200 grain pills are devastating on elk, with 1/2 MOA accuracy out to 500+ yds when I launch them at about 3200 FPS. No pressure signs when doing this therefore I'm comfortable saying that I'm not wrecking my brass either! Note that I use this caliber to hunt, not shoot 1000 yard competition...so if that's a serious consideration disregard and concentrate on the heavier pills.

DoubleGobble00 said:

I shot my first rounds of hand loads this weekend for my 300 Rum. I loaded the following:

Nosler brass (first 5 new brass, others 1x fired)

215 M primers
Imr 8133 (88.5 to 91 grains)
Berger 230
Neck size only

The 89.5 and 91 loads had primer cratering bad. All shots had ejector marks and slight crater. I'm thinking my headspace is too tight that could cause this? My brass is pretty tight when chambering. All my factory ammo shows ejector marks also. I was hoping to get more velocity since I have 29" barrel.

On separate note, which do you think I should start next steps of load development? Also, if I full length size could I get more velocity and lower pressure?

Thanks,

DoubleG

Click to expand...

What rum do you have? I have a Remington senders rum and it really likes imr 7828 and I use 85 grains with a 225 Hornady eld and they all Touch at 100 yards and go 2930 with a 26 inch Barrel I could push it to go faster but it shoots really good so I leave it alone. I did use the same load with 215 Berger and had the same results with a little more velocity. Hope this helps

On your case issues, you seem to have brass flowing such that you are heavily working the case near the web (the thicker portion) near the base. This could be because of the way you are prepping your brass. and or the nature of your chamber. Under normal mechanics the brass flows forward in the chamber. If pressure is high or there is no room on the front end the brass can flow in the reverse direction causing ejector marks and primer issues .

If this is happening with new brass try full length resizing the new brass with a .001 to .002 shoulder bump. Trim it .001 under the trim to length . These steps will make sure the brass can flow forward and use a powder load that is below the max. If this is reverse flow issue has happened with new brass you can get a case bulge just forward of the web . It will appear like a dark ring on the case and FL sizing will never completely remove it . We used to get head separations on 7 STWs there.

The bottom line is to stop the bulging and rearward brass flow you have to prep your brass to allow room at the should and case mouth .

This will also give you more stable pressures .

I've been going thru this with my remington long range factory rifle.
So far (50 rounds of testing) it's looking like it will produce 3000 fps with 90.6 to 90.9 grains of H1000 with the Berger 215 hybrids. It's producing good groups at that speed so might be where i'm at with it.