.300 RUM + US869 + 240SMK load dev quandry

[mattj]

Hello LRH friends -- I've hit a bit of a load development head scratcher that I'm hoping folks here can help me out with.

I have a very accurate H1000 load worked up for my SSG custom .300 RUM -- stupid low ES, tiny groups, and all that good stuff... but let's face it, a pitcher that throws a 101 mph fastball is much more exciting than one that throws 86 mph

Based on advice from you folks, and especially Jon A's well documented success with .300RUM/240SMK/US869, I'd thought I'd give US869 a whirl (note: CCI 250 primers).

I've had really good luck with the OCW method -- so I loaded 5 rounds each from 96 to 102 grains of US869 (and some fouling rounds) and hit the range.

I did the whole round robin thing over my chronograph. On the upside, I certainly got my fastball. 5-shot average of 2998 fps at 101 grains with no pressure signs, 3026 fps at 102 grains but the bolt was a bit sticky.

The 101 grain isn't too shabby, ES: 16, STDEV: 6.67 -- it grouped sub-MOA, and if my previous load development with this gun is any indication, I'd bet I could tweak the seating depth and get it to make itty bitty groups... if I could get it to always stay 60 degrees where I'm shooting.

So there's the rub: plotting both the average Y-axis POI's and the average velocities versus the powder charge, I get basically straight lines -- no apparent 'nodes' to be had. I've never really had that happen before, and I'm not sure what to do about it...

I could be happy with 3000fps and ES of 16 from the 101gr load, but from what I understand, this isn't the most temperature stable powder... That wouldn't make me so nervous if I could pick a charge in the middle of a big fat OCW node --- but in this case, a little "hotter" gets me pressure signs and an ES of 50+, and the 100gr load's ES/SD numbers are pretty crummy. I'd hate to burn more barrel only to develop a load that only works well on mild spring days.

I don't really know where to go from here --- given my awesome results with H1000 (save the lackluster velocity), I don't think I have a reloading technique problem (doing everything the same way in terms of prep/loading process). I could try a different primer, but I don't quite see how that would address this particular issue...

Am I making too much of my apparent lack of obvious OCW nodes? Assuming not... any ideas?

I'd hate to give up on the powder, as the velocities are definitely nice... that and I bought 8lbs of it (take what you can find these days!).

Your thoughts appreciated... thanks guys!

-Matt

 

[338 LEGEND]

Im getting ready to test 869 in my 300 ultra too. Are you on the lands if not how much are you jumping?

 

[J E Custom]

The H-869 powder is a ball powder and "IS" temp sensitive but only at high temps (85 to 100+)
and is not an extream powder but if you can stay at or below 80o you should be ok.

If your going to use the slower powders like H 869 I would recomend the fed 215m primer
and this should bring the SDs down a bit.

J E CUSTOM

 

[royinidaho]

My experience with US 869 is spot on with J.E. Custom's comments.

Regarding the primers, it was recommended to me by one who is knowledgeable, to use the Fed 215s instead of the Match Feds as they are a bit hotter.

869 charges are 93 gr for a 102gr for a 150 class bullet, 101 gr for a 170 class and 93 for a 195 gr in .277 cal.

 

[mattj]

338 LEGEND: Jumping them .015" for now (that's what my H1000 load likes)... I will tweak with seating depth more once I get this other stuff figured out.


J E Custom & royinidaho: Thanks for the tips... I'll give the Feds a try (just have to find some!)

-Matt

 

[jmden]

Sounds like you're stuck. Might try the 215's as suggested.

I've seen 869 recently listed as an extreme powder on their site, but I don't think it is. I've burned through 8 lbs of it (and a barrel ) shooting 240's and 200AB's in the 300 RUM. I try not to shoot in temps above about 50-60 as I've noticed the velocities take a 50fps or so jump at that point.

Right now I'm shooting 104.2g for MV's just under 3K (~2994 or so) with fed 215M's and on the lands. Might be a bit more capacity in my case than some as I use a Redding comp shellholder of +.010 to get the fit I want and am shooting with the 240 on the lands using the 4" Wyatts box. ES is ok at right around 20 fps if I take out the lowest and highest velocity in the string first.

Good luck.

 

[trueblue]

What were you shooting before to get tiny groups, and stupid low ES, and if it shot so well, why change a good thing ? Did you go up in weight of bullet, or something else specific.

 

[mattj]

Sounds like you're stuck. Might try the 215's as suggested.

I've seen 869 recently listed as an extreme powder on their site, but I don't think it is. I've burned through 8 lbs of it (and a barrel ) shooting 240's and 200AB's in the 300 RUM. I try not to shoot in temps above about 50-60 as I've noticed the velocities take a 50fps or so jump at that point.

Right now I'm shooting 104.2g for MV's just under 3K (~2994 or so) with fed 215M's and on the lands. Might be a bit more capacity in my case than some as I use a Redding comp shellholder of +.010 to get the fit I want and am shooting with the 240 on the lands using the 4" Wyatts box. ES is ok at right around 20 fps if I take out the lowest and highest velocity in the string first.

Good luck.

Yeah, I'm worried I might be stuck as well, unless I can find some Fed primers and they do something magical.

Trying to understand what you gain by dropping the high and low values when looking at your ES... seems if ES is the value is what you are interested in, then the high and low values are the most valuable piece of information; unless you don't trust the consistency of your chrono or something. Just curious

 

[mattj]

What were you shooting before to get tiny groups, and stupid low ES, and if it shot so well, why change a good thing ? Did you go up in weight of bullet, or something else specific.

Just that the velocity is in the mid 2700 fps range... if I can have the same cake up around 3000, I'll eat it... More energy, shorter t.o.f., less wind drift, flatter trajectory, etc. 8+ percent improvement is nothing to sneeze at!

 

[jmden]

"don't trust the consistency of your chrono or something" bingo... No screens, not mine, changing lighting conditions at a range where I have little control over the chrono. Do the best I can when I'm there. Have had pretty consistent luck doing this over the years and using the MV average I come up with. Need my own chrono. Purchased a CED M2 last year and it just did not work--to put in nicely. Others seem to have had good luck with theirs...

 

[mattj]

Ah, gotcha... makes more sense to me