hattori.hanzo Posted March 12 Report Share Posted March 12 Hi everyone, so far, I have used N160 for my 284 Win with Lapua cases and Lapua 180 grs Scenar-L bullets. Now, I have tried to calculate two loads with new RS 70/76 powders using GRT and previously measured the water capacity of my fired cases. I am surprised by the results: The slower RS 76 powder is burning faster? Somehow, nothing really makes sense: The fired case size don’t fit to CIP specifications. I have measured P1 12.17 mm and P2 12.72 mm for the fired Lapua cases. This is significantly more than what the case should have according to CIP, especially at the shoulder. Also, the case volume with 68.60 grs H2O is significantly larger than what is noted in the GRT database. Actually, it looks more like a 284 Shehane! Can you draw any conclusions from the data? Thank you Uwe Quote Link to comment Share on other sites More sharing options...
No i deer Posted March 12 Report Share Posted March 12 Just stick with N160.. 54grs or so behind a 180gr.. If you wanna go fast 51.8gr to 52grs of RS60 will do the trick.. Work up though Quote Link to comment Share on other sites More sharing options...
hattori.hanzo Posted March 12 Author Report Share Posted March 12 I already have a load in this range with N160. The 3.5 kg power can is empty and I would like to try a powder with more energy. Quote Link to comment Share on other sites More sharing options...
No i deer Posted March 12 Report Share Posted March 12 I'll ask a few f class shooters and see if they've used the RS70/76. I think RS70 is similar to RS60. Quote Link to comment Share on other sites More sharing options...
Richiew Posted March 12 Report Share Posted March 12 It’s going to depend on how easy it is for you to get powders. If you’re happy with Vihtavuori I’d try the 560 or 565 load info . Going off the web app try a 175 Berger if you’re after a bit more speed . Hope you find what you’re looking for. Quote Link to comment Share on other sites More sharing options...
Richiew Posted March 12 Report Share Posted March 12 Quote Link to comment Share on other sites More sharing options...
No i deer Posted March 12 Report Share Posted March 12 A mate tried RS70. He was trying to shoot a load with reduced pressure. He used 53.7grs behind a 180gr hybrid with an mv of 2790fps.. So there should be plenty of room for extra velocity.. As the saying goes. Speed for vanity accuracy for sanity 🤪 Quote Link to comment Share on other sites More sharing options...
No i deer Posted March 12 Report Share Posted March 12 My mate said he took it up to 55grs and velocity was 2860fps. This is from a 32 inch barrel. If I used 51.8grs of RS60 in my 26 inch barrel I could get 2880fps. Accuracy is very good at 1000yds Quote Link to comment Share on other sites More sharing options...
hattori.hanzo Posted March 12 Author Report Share Posted March 12 Ok, looks like a possibility worth trying. Many thanks for your help! Do you have any clue about the high case volume of 68,6 grs H2O out of a straight 284 Win? (See initial posting.) Quote Link to comment Share on other sites More sharing options...
No i deer Posted March 13 Report Share Posted March 13 I think my mates H20 capacity was 57.5. Personally I like to have a quickload ran but most of the info on it is way beyond me.. I'm just looking for approximate speed and where max is as a guide.. Quote Link to comment Share on other sites More sharing options...
hattori.hanzo Posted March 13 Author Report Share Posted March 13 4 hours ago, No i deer said: I think my mates H20 capacity was 57.5. This doesn’t seem to be correct. This is pretty much the 308 Win capacity. As per GRT manual, I need to measure H2O at room temperature of fired (not sized) and length trimmed cases. I will give RS 70 a try with a staring load at pmax -25%. RS 70 is reported to burn much more aggressive than calculated. So I need to be careful. Quote Link to comment Share on other sites More sharing options...
No i deer Posted March 13 Report Share Posted March 13 I think his was norma brass Quote Link to comment Share on other sites More sharing options...
Leeman Posted March 13 Report Share Posted March 13 Your case measurements can't be correct. If P2 (the case diameter at the shoulder) was bigger than at the extraction groove (P1) the case would be wedged in tight. Maybe you have those numbers transposed? My Shehane fired cases measure .4860 at he shoulder and .5005 just above the extraction groove. A standard .284 would be .475 at the shoulder. Quote Link to comment Share on other sites More sharing options...
hattori.hanzo Posted March 13 Author Report Share Posted March 13 You are right, I have nixed up P1/2. 😵💫 P1: 12.73 mm / 0.5010 inch P2: 12.17 mm / 0.4790 inch Quote Link to comment Share on other sites More sharing options...
Leeman Posted March 14 Report Share Posted March 14 22 hours ago, hattori.hanzo said: You are right, I have nixed up P1/2. 😵💫 P1: 12.73 mm / 0.5010 inch P2: 12.17 mm / 0.4790 inch You will have to check with the gunsmith who fitted the barrel, what reamer he used or what is stamped on the barrel, as the cartridge designation? Quote Link to comment Share on other sites More sharing options...
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