300RUM users - any insights into these results?

[PWS]

A little background, I have an opportunity to work this summer at a remote location where shooting is almost unlimited in direction and distance. With that in mind, I picked up a Sendero 300RUM this week and fired the first test loads today. I have one more week to come up with a final load and due to time and location constraints, only have the choice of 2lbs of Retumbo and 8lbs of US869.

Are these results where they should be in terms of velocity from this 26" 1-10 barrel or am I leaving some speed on the table?

Hornady 225grELD-M (one shot each, just getting on paper w/Retumbo so no impact info, but US869 appeared to cluster around 101.5gr/2960fps)

Retumbo US869
84.0 - 2788 99.0 - 2801
84.5 - 2788 99.5 - 2810
85.0 - 2810 100.0 - 2864
85.5 - 2822 100.5 - 2885
86.0 - 2863 101.0 - 2919
86.5 - 2879 101.5 - 2966
87.0 - 2890 102.0 - 2908
87.5 - 2911 102.5 - 2957
88.0 - 2925 103.0 - 2991

Berger 215Hybrid (one shot each, Retumbo clustered around 89.0gr/3000 and US869 around 102.0gr/2950)

Retumbo US869
86.0 - 2871 100.0 - 2871
86.5 - 2921 100.5 - 2956
87.0 - 2912 101.0 - 2916
87.5 - 2932 101.5 - 2925
88.0 - 2960 102.0 - 2949
88.5 - 2964 102.5 - 2950
89.0 - 2999 103.0 - 2990
89.5 - 3004 103.5 - 3023
90.0 - 3031 104.0 - 3020

The Hornadys gave me a few flyers that resulted in overall group size around 2" for all the shots in the ladders at 100 but the weather was rotten, 15-20mph wind from 1:30, 40degrees, and driven rain (ya, lots of fun but at least the range is mostly covered). Bergers hovered around 1 1/4" at the same distance. At this point, it looks like I'll have more Bergers sent to me and load 102.0gr US869.

Brass is new ADG and showed no extractor marks or "signs" of high pressure although the heavier loads did cause a little more scuffing. The Fed215s showed a little cratering with all loads so I ignored it. Loaded lengths were single-feed at 3.900" for the ELDs and 3.915" for the Hybrids.

Thanks for the comments!

Mike in Kodiak

 

[fourpower]

I load my 300RUM with 210 bergers with 90gr retumbo and it shoots lights. gun has a 28in barrel and loves this load. had trouble with some new Remington brass so I got some norma for my trip to Africa. only problem was with new brass my load was going faster. in new brass it is now going 3225 fps! I had to resight in Africa but 8 big animals didn't like it as they all hit the deck.

 

[PWS]

Thanks for the response, fourpower! 3200+ is humming!

I managed to scrounge up two more pounds of Retumbo at the locale gun show/swap meet (it's always the same 10 of us with tables and about 300 walk-ins) so I've got another set of ladders loaded up and tomorrow's forecast is for much better conditions. I'll try to shoot them at 300yds and see what happens. From my searches, I think the barrel is producing appropriate performance but I'll post tomorrow's results.

 

[Beeman]

I had a Sendero 300 RUM as well. It shot really good but the barrel was on the slower side. It is shot out now. I only loaded the 215 Berger with H1000. My load was accurate but only produced 2985 fps. So to me your velocities look good.

 

[FrankG]

So some food for thought.....

If I remember correctly according to my twist calc’s the Hornady 225’s at 2800fps need a 1-9.52 min. Twist. So your twist of 1-10 might be on the ragged edge of stabilizing those bullets.

Also this is a factory barrel correct? If so in button made barrels (Rem. Makes both button barrels and hammer forged barrels) twist uniformity can be a issue. Not to mention bore and groove size uniformity. If the twist isn’t uniform you might have a true 1-10 twist or you could have a barrel that starts out at 10 twist but ends at 10.6. That’s just an example. I’ve seen barrels that have gotten as slow as almost one full twist. It could start out at 10 slow down to 10.7 and speed back up to 10 twist. Either way you end up with a non uniform twist. To me this is just one reason that can make the barrel very tempermental it terms of what it likes for loads/bullets etc....also to bore and groove size/uniformity....if the barrels bore is on the looser/big size it might like a fatter bullet. Again the barrel will be more tempermental as to what it likes or a particular lot of bullets might shoot better than a different lot etc...

Later, Frank
Bartlein Barrels

 

[PWS]

Managed to get to the range yesterday and ran the ladders again. This time, it was at 200 because it was raining but calm and foggy and trying to see a bullet hole in a soggy target at 300 would have been futile. I also upped the maximum loads in the ladders.

225Hornady:

Retumbo 89gr - 2921
90gr - 2978

US869 104gr - 3047
105gr - 3068

215Berger:

Retumbo 91gr - 3036
92gr - 3085

US869 104gr - 3065
105gr - 3091

Although there were speed gains, faint ejector marks started showing and in every instance, the higher charges threw the shots further from the overall group centers. I also monitor case web expansions per Ken Water's technique, (whether valid or not) since it's one more bit of information to help understand what is going on, and loads over .5500" expansion appear not worth the increased risk of brass movement.

Thanks for the input, Beeman and Frank, I don't think there is anything special about this factory barrel. I'd rate it about like the $150 Wilsons I've chambered - fine for the price point. 26" isn't going to produce any extra speed and it wouldn't surprise me if it wasn't particularly precise in dimensions. The factory crown was horrendous! It's not super smooth but without a break-in it doesn't foul much or seem to be sensitive in that regard. I can see that it has a big curve by comparing shadow rings down the bore and the throat was obviously not cut concentric with the bore.

For all that, the overall size of the ladder groups were just over 2" at 200 and, thankfully, the same sweet spots in yesterday's 215 ladders correlated with the previous ladders.

Since I'm out of time, I'm going to run the Bergers with 89gr Retumbo for ~2975fps and then swap to 102.5gr US869 for about the same speed when the Retumbo runs out.

The 225s seemed to group almost as well as the 215s with no evidence of tipping so when my Bergers run out, I'll run them over the same charge of 102.5gr of US869. Four sequential shots of the ladder of nine went into 1" at 200 at that load level so just under 3k appears to be a good place with both bullets and both powders.

I should be able to do a few quick OAL ladders but they're all be off a bipod down a hilly logging road so not quite as a controlled environment as the range here in town.

I'll check in now and then and report anything particularly good or bad but it looks like I'm ready to go plink and dink!

 

[PWS]

FWIW, I shot a “Berger seating depth test” with the Hornadys and Bergers. This was off a backpack and bipod, through a gap in some spruce branches, down a log spur and up a corner at 237 yds.

Hornadys seemed to prefer a good bit of jump (started at .010” off)
3.900” - 1.23moa
3.860” - 0.93moa
3.820” - 0.83moa
3.780” - 0.63moa

Bergers shot well at .010” off and even better at the next step but went kaflooie beyond that.
3.915” - 0.73moa
3.875” - 0.55moa
3.835” - 1.41moa
3.795” - 2.22moa

This is in the Rem factory chamber and barrel.

 

[Zero333]

I would be plenty happy with sub moa results shooting 100 grains of powder through a Remington factory barrel.

 

[Laurie]

If so in button made barrels (Rem. Makes both button barrels and hammer forged barrels) twist uniformity can be a issue. Not to mention bore and groove size uniformity. If the twist isn’t uniform you might have a true 1-10 twist or you could have a barrel that starts out at 10 twist but ends at 10.6. That’s just an example. I’ve seen barrels that have gotten as slow as almost one full twist. It could start out at 10 slow down to 10.7 and speed back up to 10 twist. Either way you end up with a non uniform twist. To me this is just one reason that can make the barrel very tempermental it terms of what it likes for loads/bullets etc....

I knew of such twist rate discrepancies in mass produced barrels, but hadn't realised they could could be this big! No wonder some factory rifles are picky and/or impossible to get to shoot well.

 

[B Nettesheim]

Why not bring your reloading equipment with you if possible?

 

[PWS]

Why not bring your reloading equipment with you if possible?

I have a rudimentary kit on hand, Huntington Compac press, dies, preset powder measure, but have to load at an office desk and store everything in the drawers when done. Believe me, I’d love to have access to a bench mounted press, scale, and all the other gadgets and goodies at home, not to mention a chronograph and a real bench and shooting range.

This is all for practice, fun, and entertainment after hours. A shooting coworker and I have around 23 (iirc) steel plates from 400 to 1900 yards so far and we’re scouting out some place for 2k.

Gotta admit the wind is a killer here, being hilly logging cuts right on the North Pacific coast.