Re chambering by hand
- Thread starter DGY
- Start date
Really, I would have thought it would be quite a bit more. But my wife always tells me, what I think and reality is not the same.
Measure the difference in case capacity, then divide by four. For example, if I gain 10% capacity, I will gain 2.5% in velocity. Rough calculation, but it's not too far off in my experience. - dan
Really, I would have thought it would be quite a bit more. But my wife always tells me, what I think and reality is not the same.
Read some of Parker O Ackley's books or even just appropriate snippets about his experiments with improving cartridges by decreasing the body taper and pushing the shoulder forward for a one-diameter or slightly less neck length.
10X is right IMHO.
There is a recipe to mathematically deduce how much velocity increase you will get with powder increases. It's reasonably reliable but it was factored around IMR powders that were available 50 years ago.
The OP is happy with an appx 75 fps velocity increase. It's worth it to him for all sorts of good reasons, such as a learning curve project.
There are all sorts of things that would give similar increases in velocities, which IMHO are marginal when it comes to effectiveness in hunting situations, but might improve accuracy or just make the shooter feel good about his project.
After the OP posted this project, I took three different 8x57 rifles to the range and recorded the velocities of five rounds each hand loads that were loaded to European commercial specs for the JS type bullet (.323) In Europe, the onus is on the shooter (common sense) to know the diameter of the bore.
My load was 55gr W748, over cci250 primers, under 170gr Hornady IL. which should generate 2700fps. This is not a maximum load for 98 actions unless they are in poor condition.
Each of the three rifles had appx 23.5 inch barrels, one of which is commercial and two are military.
The velocity deviation wasn't more than 25 fps in each rifle, but the average velocity deviations between the rifles differed by just over 60fps, from slowest to fastest (commercial).
I did this because the OP's experiment got me thinking about something I had already been through, chasing elusive exceptions.
He's having FUN, while learning. If he gets a slight velocity increase as well, he's been successful.
But keep in mind, he's pushing the "deemed safe" limits of his rifle.
I really like to see people do such experimenting. It helps them establish what's worthwhile and what isn't.
I recently went through a similar experiment trying to "upgrade" a 7x57 chambered rifle by reaming out the chamber to 280 Remington (7mm Express)
Both of those cartridges were limited in their performance, which was already excellent, by the actions they were originally chambered in.
The 7x57 in 93 Mausers and the 280 Rem in pump and semi auto Remington actions. Both of which are strong but not as strong as modern bolt actions. So, the loading manuals reflect this issue by listing loads that generate pressures suitable for the "weakest" actions they will be used in.
When all was said and done, all I achieved was a 3% increase in velocity and exactly the same accuracy over the 7x57 loads that generated similar pressures.
I load the 7x57 HOT, because the rifles I have chambered for them are strong. Same for the Whitworth Mauser I rechambered to 280 Rem. My loads are much hotter than those listed in any reloading manual but are safe in my rifle.
Really, I would have thought it would be quite a bit more. But my wife always tells me, what I think and reality is not the same.
MRP, when you're generating much more velocity than you should be getting, something is wrong with the powder charge. Of course, you know this.
Once you start noticing severe spikes in velocities, you're way beyond safe pressures, unless you've stumbled across a unicorn powder/primer combination, or you've reached that point where you're approaching saturation and pressures are spiking beyond acceptable limits.
Some of the new powders that were available, were generating higher velocities in cartridges they were suitable for.
For instance, the OP listed CFE223, which is very close to BLC2, which generates some of the best velocities in the 8x57 Mauser and the 8mm-06. That was a great choice to experiment with on his part.
The one caveat with this powder is density. IMHO it doesn't fill the case enough for reliable consistent burns in the field. It should be fine under controlled conditions, such as off the bench.
