Load development? 300rum, 230gr, RL33

[Lefty7mmstw]

Did some load testing looking for pressure today. Started at 96gr and loaded 2 rounds each up to 102gr. I'm not real sure what to think. My accuracy was great with all loads under 1/2" at 100 yrds. I showed faint ejector marks on one of the 99gr rounds, one of the 100gr rounds and then I blew a primer out on one of the 101gr. There was never a hard bolt lift and the ejector mark even on the blown primer is still very faint.... Bad case maybe?? All these were loaded 10thou off the lands. Velocity really didn't increase until I got the the 99gr load. It shot average of 3075fps. I shot over my chronograph at about 15' away but it's not looking like I'm gonna reach 3150fps. I'm fine with that but the blown primer has me a little lost since there were no real pressure signs before it happened. Even on the other 101gr round...

I doubt it's a bad case. Montana rifleman had to back off to 96 grains with his 300rum with rl33 and the 230 berger. I'm running the 225 hornady and 220 nosler lately in my 300rum with rl33 and with them 95 grains will put a bit of an ejector mark on the brass if the temp is up and I let the rifle get hot. Some like doublezranch have been able to get over 100 grains before they got vel., though.

 

[CogburnR]

I went up to 99g Rl 33 with the 230 OTM. I measured some case head expansion at 99g at a velocity of 3041fps.

I have some loaded at 97g for testing once I get time, they run about 2950fps.

 

[dodgefreak8]

Little different results today.. Not real sure why but they are promising. I wanted to tinker with seating depth but I only had a limited time to shoot today so I didn't get through all my strings. Here is what I found today.

First 5 shot string 95.5gr .015" off the lands
3122
3144
3144
3159
3144
AV- 3142
ES- 37
SD-13
Numbers look great but at 200yrds I shot a 2" group... Could have been me I guess

Second string 100gr .010" off the lands
3174
3174
3197
3220
3189
AV-3190
ES-46
SD-19


Group on top is the first string and the group on bottom is the second. It measured just under 1" @ 200yrds

I'm not real sure why the sudden increase in velocity but I had zero signs of pressure this time. I think I am going to tinker around with the 99-100gr area since it is right where I was hoping to get with velocity. I'm still going to drop a few grains to do the ladder test when I can get to my 500yrds range. This rifle is going to be an absolute tack driver though!

 

[MMERSS]

The ES seems rather high. Good group though. What chronograph? I've noticed in my RUM I need .005" jump for best ES results (lower teens).

 

[Doublezranch]

I have done endless testing with 33 and 230 berger. I am running 101.3 (down from 102.3) grains of 33 in a 27.5 inch benchmark. COAL is 3.98. I'm right at 3200 give or take a foot here or there. I did find that heat plays a huge factor in 33. 102.3 was amazing velocity, but brass life was terrible. Thanks to Barnsuser28 telling me to drop a grain. I found that accuracy stayed the same with, velocity hardly changed, and brass life is much, much better.

 

[dodgefreak8]

The chronograph is a prochrono. I thought about going trying .005" from lands but I don't want issues while hunting from being so close. I had a three shot group that had an ES of 7fps but the group was horrible. It was shot from .010" off the lands. Doublezranch what distance are you from the lands?

 

[Rocky Mountain]

Wow 3200fps with 230gr in a 300 RUM is way more than I've heard must be a fast barrel.

 

[Lefty7mmstw]

I hate to be a naysayer here but rl50 seems to be a better powder than rl33 with some of the bigger bullets in the 300rum. The biggest problem with rl50 is you are usually using a rather compressed charge. I haven't gone to the dark side yet in the 30 cal's so I'm not really sure how the berger 230 works in my rifle.
My rifle ( a stock lh bdl) likes the 225 hdy at 95 grains rl33 (3000 fps) but it also likes rl50 at 100 grains (also 3000 fps); both are right at .6 moa at 200 yards. When I switch to the nosler 220 hpbt I can get 102 grains rl50 in the case easily and get .5 moa, but rl33 at 95 grains is already stout and the group opens up to 1 moa; I haven't chrono'd the 220 nosler out of my rifle yet.

 

[brentc]

I'm betting the group tightening had more to do with moving the bullet closer to the lands at .010 off than anything powder related. It looks to me that your rifle likes that seating depth. I'd continue working around that seating depth and continue development with powder charges around that 99.5 - 100.5 grain range looking for the balance between accuracy and ES.

 

[Doublezranch]

It's a 5r 1-10 twist benchmark Remington heavy varmint. It's amazingly accurate and very fun to shoot. My case overall length is where I gain a bit. It's 3.98. I had it longer but 10 thou off the lands was too much pressure. I backed it off to 50 thou and was able to gain velocity with more powder. I was also suprised to see the numbers. I figured it would have been less myself. I was what you call presently suprised.

Lefty...your never a nay sayer. I look at you as a realist!! That's why I value your opinion.

 

[dodgefreak8]

Thanks everyone. I have 5 rounds loaded with 95.5gr and seated to .010" from the lands. Going to try this out one evening this week and see where they group. I'm looking for extended brass life as well so that will be an important factor as well.

 

[Tumbleweed]

I shoot a full custom Rem 700 300RUM with a 32" Broughton 5C in 9 twist. It does have a custom throat and acts much different than a more "SAAMI" type chamber. I also use 230's and RL33. In load development last fall, I worked up to 104 grains of RL33 before I got into any real pressure issues. Velocity was around 3,280 fps. I ended up backing down to 101.5 grains with a seating depth of 3.830" which will allow them to fit in the mag. It also created close to 100% load density. There is virtually no extractor mark on the case and primer looks like it was a mellow factory load. Accuracy is .25 to .5moa depending on me. Velocity is slightly over 3200fps with pretty wide ES. The funny thing is that the ES has not seemed to affect accuracy or vertical spread even to 1,370 yards. If I do my job VS is inside .3moa.
After learning more about the characteristics of RL33 I would have probably designed a throat that would allow my bullet to reach the rifling to bring the ES down. But, it is accurate and fast so I'm happy. I hope this helps in some way.

 

[live2huntmt]

@ Tumbleweed

Is your custom throat longer or shorter than a SAMMI throat? From what I gather, it seems like it is longer. If so, what is the reason behind this? The only reason I am curious is because I am thinking about rebarreling my Rem 700 300 RUM and asking the gunsmith for a shorter throat so I am able to reach the lands and still feed it through my box magazine.

Thanks

 

[dodgefreak8]

I shot out to 500yrds yesterday with great results. This target was at 300yrds with a great group! I did some trajectory validation and found out my velocity is closer to 3250. At 500 yrds I shot high of this same 6" steel. I was dialed up 1.5mrad to match my ballistic app. Had to dial down a click and hit dead center twice in a row. We forgot to go get that steel plate to see the group :-( I'm at 100gr of RL33 and shooting .010" off the lands. COAL length is 3.815"