300 rum load development

[DoubleGobble00]

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

 

[tbrice23]

Was this 100 yds?

 

[tbrice23]

I have a 700 Long Range that was tight on virgin Norma brass. The headspace was only .002" to .003" larger than my chamber. 1/2" above the rim was also only .002" smaller than my chamber.

 

[DoubleGobble00]

Was this 100 yds?

225 yards

 

[screech]

Maybe try rl33 see if it gets you more velocity

 

[FURMAN]

There is zero valuable data on that target. Back up and repeat or do a different load development method.

 

[DoubleGobble00]

Honestly, I was just using the target to glean some data while looking for max load. I think there is some good info in the velocity and maybe some of the vertical data on target. Further would have been better but I'm limited at my place. This was all I could get.

 

[DoubleGobble00]

Pretty much all the loads I've shot with this gun have an ejector mark. I'm not sure why... I did get slight bolt sticky and bad primer crater at 91 so I consider this max.

 

[can1010]

repeat 87-88.5 with fired brass. full length resize with .002-.003 bump. fired brass will pick up some velocity put the few loads I tried with 8133 were not fast and pressures were high. rl-33 has always worked for me

 

[DoubleGobble00]

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

 

[FURMAN]

I sometimes put my pressure test while breaking a barrel in on paper at 100 yards just to see. I really did it to see if it would give an usable data and at least 50% of the time the "groups" were not repeatable. This tells me it is not useful. Do what you want but there is a 50% chance your wasting components and barrel life by following the advise of others. It makes no difference to me but like I said I have tried it and it just doesn't work. If you are limited by distance do the ocw. If you happen to find a load your rifle likes with new brass and it falls apart with fired brass just back the charge down a grain and work back up the node will be there.

 

[can1010]

I liked h-1000 with lighter bullets 180-210. retumbo is not bad but rl-33 really shined with the 230

 

[lancetkenyon]

I use Retumbo in my .300RUM w. 230 Hybrids. Temp stable, good speeds, great accuracy. 28" Rock Creek 1:10".

 

[DoubleGobble00]

The Retumbo velocity you got was great... I'd be happy with that for sure