Load Testing over different powders?

[longrangehunter]

So in the past I didn't like doing load development over another powder/bullet. I noticed some powders have a different Slickness to them in the barrel?

Anyway, I just put 5 rounds through the TRG-42 w/ the load I developed using 78.0 of IMR 4350. I ran out of the previous lot, and had to use a different lot # for the last two rounds then what I used for barrel break-in. Shot very well, one hole with the new lot of powder, but I'm tempted to see if I can achieve the same accuracy and increase the velocity at the same time using a different powder?

I now will need to use a different powder, RL 25, or 33, H1000, 780 Supreme, or N170, etc.

What is everyones opinion on shooting over a previous powder with a new powder using the same bullet during load development? I now have twenty rounds down the tube, it had been completely cleaned down to zero fouling before the last 5 rounds were fired.

Should I bother to clean the barrel prior to starting over with a new powder or just shoot over the fouled barrel?

 

[SJB358]

I'd just shoot it to be honest. I haven't noticed big differences in lots of powders, especially this early in the game. If your bumping up into the max charges, then I'd hesitate, but not in your case.

 

[longrangehunter]

I'd just shoot it to be honest. I haven't noticed big differences in lots of powders, especially this early in the game. If your bumping up into the max charges, then I'd hesitate, but not in your case.

Hey Scotty,

According to Sierra's Manual 78.2 is max with the 300 SMK and IMR 4350. I wasn't anywhere even close to their velocity of 2650, 2525 fps w/ a 27 1/4" bbl vs. their 26", a 125 fps seems excessive for the difference, or maybe I just have a really SLOW barrel.

PS: I did not run the two rounds over the chronograph with the different lot. I thought if I saw a difference in grouping then the powder must be off? I did notice a very light ejector mark on all 20 pieces of brass though, which I hadn't seen before today.

 

[SJB358]

I think all of the data is hard to get exactly what the book states. Seems like it is more off than on, but that's just my limited experience. They could be dealing with a tighter chamber or maybe different brass. Just too many variables to guess at.

Cartridge : .338 Lapua Mag.
Bullet : .338, 300, Sierra HPBT LR MK 9300 G7 Litz
Useable Case Capaci: 92.057 grain H2O = 5.977 cm³
Cartridge O.A.L. L6: 3.681 inch = 93.50 mm
Barrel Length : 27.0 inch = 685.8 mm
Powder : IMR 4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0 81 68.40 2392 3811 48821 8523 100.0 1.605
-09.0 82 69.16 2413 3879 50212 8578 100.0 1.584
-08.0 83 69.92 2434 3947 51639 8632 100.0 1.564
-07.0 84 70.68 2455 4014 53102 8686 100.0 1.544
-06.0 85 71.44 2476 4082 54603 8740 100.0 1.525
-05.0 86 72.20 2496 4151 56142 8793 100.0 1.506 ! Near Maximum !
-04.0 86 72.96 2517 4219 57720 8845 100.0 1.487 ! Near Maximum !
-03.0 87 73.72 2537 4288 59339 8897 100.0 1.469 ! Near Maximum !
-02.0 88 74.48 2557 4356 60999 8949 100.0 1.451 ! Near Maximum !
-01.0 89 75.24 2577 4425 62702 9000 100.0 1.434 ! Near Maximum !
+00.0 90 76.00 2598 4495 64449 9051 100.0 1.417 !DANGEROUS LOAD-DO NOT USE!
+01.0 91 76.76 2618 4564 66242 9101 100.0 1.400 !DANGEROUS LOAD-DO NOT USE!
+02.0 92 77.52 2637 4634 68082 9150 100.0 1.383 !DANGEROUS LOAD-DO NOT USE!
+03.0 93 78.28 2657 4704 69969 9200 100.0 1.367 !DANGEROUS LOAD-DO NOT USE!
+04.0 94 79.04 2677 4774 71907 9248 100.0 1.351 !DANGEROUS LOAD-DO NOT USE!
+05.0 95 79.80 2697 4844 73896 9296 100.0 1.335 !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 90 76.00 2659 4709 74210 8792 100.0 1.339 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 90 76.00 2505 4179 54538 9405 99.8 1.520

 

[longrangehunter]

Thanks for the QL data Scotty! That's very interesting, I started with 73.0 grains and got 2325-01-2328; 76.0 2428-02-2434; 78.0 2515-03-2523; 78.0 2510-04-2519; 78.0 2522-05-2530. The # in the center is the shot #.

I just measured the rifle for coal/cbto to the lands w/ Lapua 300 gr. Scenar's and the Hornady 285 gr. BTHP Match bullets, those both need to be seated further out then the SMK's. There is room in the magazine box to reach the lands though. I just need to pick a powder/bullet combo and see what I come up with.

I think I'm going to try H1000 or the RL33 that's suppose to be made just for the big 338's or maybe RL25?

Have a great day Scotty and thanks again.

 

[OU812]

I never clean between different powders but I do clean between different bullets ie, all copper vs CC or a bonded bullet.

 

[SJB358]

I think I'm going to try H1000 or the RL33 that's suppose to be made just for the big 338's or maybe RL25?

Have a great day Scotty and thanks again.

I think those powders mentioned would all get you where you would wanna be with the big 338. Another fellow just posted some great results with the 338 and AB's as well, might wanna see what he ran with.

Have a great day. Hope you are having good weather out there.

 

[longrangehunter]

I think I'm going to try H1000 or the RL33 that's suppose to be made just for the big 338's or maybe RL25?

Have a great day Scotty and thanks again.

I think those powders mentioned would all get you where you would wanna be with the big 338. Another fellow just posted some great results with the 338 and AB's as well, might wanna see what he ran with.

Have a great day. Hope you are having good weather out there.

His load consisted of H1000 as well, seems like most people are using 88-92 grains w/the 300 gr. bullets. Although Berger Bullets load data shows much lower powder charges then the "other" loading manuals. ie: H1000 81.0-85.2 w/300 gr. bullets.

 

[SJB358]

His load seemed to run pretty well and with 300's that is a load that'll get it done for a long way out...

 

[IdahoCTD]

I would try H-1000 and Retumbo. No one has proven R-33 to be temp stable yet. It will likely add velocity though as it added about 80fps to my 6.5-300wm for the same pressure.

 

[.300winmag]

I would try H-1000 and Retumbo. No one has proven R-33 to be temp stable yet. It will likely add velocity though as it added about 80fps to my 6.5-300wm for the same pressure.

I agree heavily on those powder suggestions. They are great powders. I had a bad experience with Alliant powders and their "product support" less than impressed me. I have switched to IMR and Hodgedon powders exclusively. Temp stability is extremely important for long range as well. I encourage h-1000 or RETUMBO. RL-22 used to be one of my go to powders as well as RL-15, but after what I went through with them, I have personally avoided them. Not trying to start a ruckass or ruffle anyones feathers, Alliant does make good powder. I have just made the personal choice to avoid using their product when possible.

 

[longrangehunter]

I loaded up some ammo yesterday morning for the TRG-42 while the weather was still nice using H1000.

All loads were 2.9225" cbto = 3.681" coal w/Lapua Brass and H1000 20' from the muzzle.

These using F215M primers.
2@ 85.0 2519-01-2525; 2514-02-2519
1@ 88.0 2602-03-2610
2@ 91.0 2689-04-2697; 2678-05-2685

#1 and 3 went into one hole measuring .0850"; .5245" for #1,2 and 3.
#4 and 5 opened up because of a flyer on my part. So I through it out and I just didn't like it how it felt.

So I went back down to start at 88.0 gr. and tried them w/ WLRM primers this time.
2578-06-2584
2588-07-2597
2583-08-2599

I liked the SD and ES but I feel the brass cups are too soft for the firing pin in the TRG. The #6 went back into the #4 shot and measured .2585". I had some vertical stringing and #7 and 8 moved up .1600" and those two measured .2285".
The last two rounds I shot at 600 yards but I forgot to change the POI on my App and was off by a half a Mil and missed the steel all together!

I loaded up another 5 rounds using the F215M and changed the load to 88.2 grains ended up using those to adjust the scope vertically over the bore, and it was slightly off, so a counterclockwise turn fix it perfectly! I was so surprised how accurate that fix was I walked away all smiles thinking next time that steel target is going to get Smacked hard!

I may or may not change the load until further testing LR maybe today, we have zero wind today, although very overcast and looks like rain. Whenever there's no wind I tend to shot from 1000 yards away to check for accuracy, but at 600 yards I have less of a chance for the wind to play games with the flight since it's not a mountain to mountain shot.