node help

[Ridgerunner665]

I'm a little amazed at the actual burn rate of RL 26.... At least in the 280 Ackley... Its barely slower than MRP, the batch of MRP I have is .4 (Ba)....MRP is "just enough" faster that its able to reach node 4, barely.... 7828 will do it a little easier I think.

I'd love to get my hands on some IMR 7977... But I'm thinking its really too slow also.

The Ackley is at its best with the powders we've been discussing here.... MRP, IMR 7828 SSC, and RL22.

 

[Ridgerunner665]

Interesting thought....

Everybody that has a 280 Ackley and knows their actual case capacity.... Post it please.

Mine is.... 74 grains using Nosler brass.

 

[muzz]

Well I got some load with 7828ssc . Some at 61.3 with 2 different seating depths and 63.3 with 3 different seating depths. Hopefully weather permitting the next day or two I can go shoot. Thanks again all!!!

The gunsmith sure has my chamber deep. I think he did it for Bergers for the long bullets

 

[Ridgerunner665]

99% of the time, jump to the lands doesn't matter...not even if its a full quarter of an inch (some are).

 

[Mikey338]

Been reading this forum for a couple of years decided to join to say thanks for the explanation. Helps me understand why I can't get accuracy when I really push my 7 mm rem mag. I can't quite reach the next node with my 24 inch barrel running 150gr CT BT. Will get .7 inch but only around 2800 fps. I have on hand Reloder 17 which when I run through my old QL programme should give me around 2980 on node 4. I haven't tried this powder yet because I'd given up reloading for it as it shoots factory Winchester super supreme MOA consistently. I'm thinking I'll drop back to 140gr @ 3190 which should put me on node 3 if I'm correct in my understanding

 

[Ridgerunner665]

Hello,

The nodes for a 24" barrel are approximately.... 1.10 ms (node 4) and 1.23 (node 5)

Node 3 is 1.02 ms and would be at almost 3,400 fps using Reloder 17.... And over 75,000 psi... Well out of reach.

3,190 fps might get you on node 4... Maybe... And is within reach, but getting up near max so pay attention.

 

[Mikey338]

Yup had the wrong barrel length in from one of my other guns, my bad

 

[SJB358]

Yup had the wrong barrel length in from one of my other guns, my bad

Mikey, the 7mm Rem Mag is one of the cartridges that really benefits from weighing your H20 capacity. So many different sized chambers have capacities all over the map. If you want specific data for your gun, start a thread and I'll add into it whatever you want or I can. It's pretty easy stuff. I got tired of chasing with my 7mm Rem and just stuffed a 7mm MSM reamer into mine. Now it does what I always wanted my 7mm Rem to do, easily.

 

[DrMike]

Been reading this forum for a couple of years decided to join to say thanks for the explanation. Helps me understand why I can't get accuracy when I really push my 7 mm rem mag. I can't quite reach the next node with my 24 inch barrel running 150gr CT BT. Will get .7 inch but only around 2800 fps. I have on hand Reloder 17 which when I run through my old QL programme should give me around 2980 on node 4. I haven't tried this powder yet because I'd given up reloading for it as it shoots factory Winchester super supreme MOA consistently. I'm thinking I'll drop back to 140gr @ 3190 which should put me on node 3 if I'm correct in my understanding

Welcome aboard, Mikey. Always pleased to see more certified rifle cranks sharing in the fun.

 

[Mikey338]

Thanks I just wish I'd clued on to this before I'd bought my rifles would have made sure my magnums had 26 inch barrels.

 

[Ridgerunner665]

There is something still amiss here...

I asked Dewey to run those projections above at 61 grains for a reason...that shouldn't be over pressure at 3.34".

I believe its in the progressive burning characteristics of RL26...but there's not much I can do with it until I get my QuickLoad update and see some solid data from a few sources.

But don't worry muzz...you original load was/is still way over pressure...maybe not quite as bad as I initially thought, but still too hot by enough to matter.

 

[muzz]

Oh no worries. I'm givin the 7828 a shot now. I have seated my bullets deeper with it also. I hope a bigger jump will work.

 

[longrangehunter]

Great info here guys. I'd be interested to see how this measures out to my Match load for my 260 Remington or my 280 AI 150 BT ; 175 NPT loads that I developed the old fashioned way....... not completely because so many other people had used this same load in the 260 Remington. I just had to modify it a little to my own gun and test for accuracy.

Forgive me for high jacking the thread but this is very fascinating and anything to speed up the load development is always a good approach. I'll need to check the H2O capacity, will distilled water work any better vs. letting it sit over night?

 

[Ridgerunner665]

Still needs to sit out overnight to let the air bubbles come out of it...the little tiny micro bubbles that you can't really see.

I don't reckon you're hijacking it...I think muzz got what he needed...we can move on to another one and come back to his if need be.

Or start your own thread...however you wish to do it.

 

[longrangehunter]

Still needs to sit out overnight to let the air bubbles come out of it...the little tiny micro bubbles that you can't really see.

So by that you mean let the water sit in the case over night?

 

[Ridgerunner665]

Still needs to sit out overnight to let the air bubbles come out of it...the little tiny micro bubbles that you can't really see.

So by that you mean let the water sit in the case over night?

No...let it sit in a cup uncovered overnight.

The case may work...never tried it that way.

 

[DrMike]

Just let the water sit in any open container overnight, Kevin.

 

[longrangehunter]

Ok, so I used some left open distilled water in five (5) Lapua cases that all weighed 177.5 grains. (the first four all weighed that, finding a fifth took a dozen more times).

1) 232.8
2) 232.6
3) 232.6
4) 232.5
5) 232.8
____________
232.66 average grains w/water to the top of the neck, slightly rounded on all. Less the 177.5 leaves 55.16 grains of water capacity.

My match load in 260 Remington 24" BBL
139 lapua scenar avg. length of bullet 1.36"
42.7 H4350
F210M primer
lapua cases @ 2.400" CBTO = 2.800" COAL

I average 2750 across my P35 for the muzzle velocity. So tell me from everything I've read from this post and a few others about this subject what can be found from the info I gave you and how it relates to the Ba number and a node?

Thanks in advance........

PS: I don't have Quick Load.

 

[Ridgerunner665]

Thats a pretty warm load...

Ba adjusted from .5130 to .5030...you are within 2% of node 5 (1.23 ms)...a little on the fast side though, maybe could be better though...have you tried 42.2 or 42.3 grains?

Cartridge          : .260 Rem
Bullet             : .264, 139, Lapua Scenar GB458 6018 G7
Useable Case Capaci: 45.898 grain H2O = 2.980 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 24.0 inch = 609.6 mm
Powder             : Hodgdon H4350 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.468% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-04.7   98    40.70   2628    2132   51024   9009     96.9    1.293
-04.2   99    40.90   2641    2152   51774   9049     97.1    1.285  ! Near Maximum !
-03.7   99    41.10   2653    2172   52535   9088     97.3    1.276  ! Near Maximum !
-03.3  100    41.30   2665    2193   53308   9126     97.4    1.268  ! Near Maximum !
-02.8  100    41.50   2678    2213   54092   9165     97.5    1.260  ! Near Maximum !
-02.3  101    41.70   2690    2233   54888   9202     97.7    1.251  ! Near Maximum !
-01.9  101    41.90   2702    2254   55697   9239     97.8    1.243  ! Near Maximum !
-01.4  102    42.10   2715    2275   56518   9275     98.0    1.235  ! Near Maximum !
-00.9  102    42.30   2727    2295   57351   9310     98.1    1.227  ! Near Maximum !
-00.5  103    42.50   2739    2316   58197   9345     98.2    1.219  ! Near Maximum !
+00.0  103    42.70   2752    2337   59056   9379     98.3    1.211  ! Near Maximum !
+00.5  104    42.90   2764    2358   59929   9413     98.4    1.203  !DANGEROUS LOAD-DO NOT USE!
+00.9  104    43.10   2776    2379   60814   9445     98.6    1.196  !DANGEROUS LOAD-DO NOT USE!
+01.4  105    43.30   2788    2400   61714   9477     98.7    1.188  !DANGEROUS LOAD-DO NOT USE!
+01.9  105    43.50   2801    2421   62628   9509     98.8    1.180  !DANGEROUS LOAD-DO NOT USE!
+02.3  106    43.70   2813    2442   63556   9539     98.9    1.173  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba    103    42.70   2814    2444   64306   9331     99.6    1.168  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba    103    42.70   2679    2215   53880   9317     96.1    1.260  ! Near Maximum !

 

[longrangehunter]

Hey Lynn,

Well the case has never shown any signs of being hot and I've fired close to 600 rounds through this gun with that load. They all fall out like a hot knife through butter.

Case head expansion .4670-.4675" vs. .4695-.4700" 1x fired cases .4700-.4705" 2x fired cases both neck sized only.

I was wondering with this info if you could tell me what would be more accurate? It's mean average is .325"-.500" MOA out to 1200+ yards. The wind plays a huge role in making those hits obviously, but on average the load has worked very well at the last three matches if I do my part.

If I remember correctly the load had super low ES and SD. I looked it up ES 25 SD 9 with the last lot of powder used.

I had only used 42.5 as a load, then switch to the 42.7.