43-287B
- Thread starter Brad
- Start date
fiver
Well-Known Member
that is.
I'm mulling this one over some more.
there is enough room there for the land lead to take up in the lube groove.
the skidding is acceptable....really.
something else is wrong.
one thing this does show is how the base moves forward not the nose coming back.
it also points to Elmer's theory of lube being pumped out during acceleration.
what this is telling me also is he went from 20-1 to 16-1 about this point in time.
the moveable/flowable alloy of low antimony would be where my attention would be focused right now.
IMO as soon as it gets compressed the antimony crystals breaks down and the quench hardness goes out the window.
this happens in swaging, and your swaging the bullet with the compression.
I'm mulling this one over some more.
there is enough room there for the land lead to take up in the lube groove.
the skidding is acceptable....really.
something else is wrong.
one thing this does show is how the base moves forward not the nose coming back.
it also points to Elmer's theory of lube being pumped out during acceleration.
what this is telling me also is he went from 20-1 to 16-1 about this point in time.
the moveable/flowable alloy of low antimony would be where my attention would be focused right now.
IMO as soon as it gets compressed the antimony crystals breaks down and the quench hardness goes out the window.
this happens in swaging, and your swaging the bullet with the compression.
Ian
Notorious member
Brad, I think Fiver is suggesting more tin also.....
What do Rick and Jim always say about revolver bullets? They want to see the bullet unchanged after firing except for rifling engraves. NO flow, no slugging-up. If the alloy can flow it will do all sorts of shape-shifting before it gets in the barrel, which is what we want in a rifle with fixed chamber/throat/bore relationship where the gun aligns the bullet, but not in a revolver where the bullet is aligning the parts of the gun.
If you have a bullet that's a few thousandths larger than groove diameter and doesn't have enough breaks in the driving surfaces, the whole bullet is bound to flow some. But we don't want that, do we? We want deep, straight-sided lube grooves and crimp groove so that the alloy can displace right at the surface as it squeezes into the barrel and takes the land impression without the whole bullet extruding .
I have an idea. Cast some bullets with more antimony and tin. You have a lathe. Make a collet to hold your bullets, and turn some with one or two narrow, square relief grooves in the nose.
I think you're getting closer to finding why this bullet type never worked well for me. Not sure why it worked so well for Rick, maybe his throats were closer to groove size and his bullets got worked less.
What do Rick and Jim always say about revolver bullets? They want to see the bullet unchanged after firing except for rifling engraves. NO flow, no slugging-up. If the alloy can flow it will do all sorts of shape-shifting before it gets in the barrel, which is what we want in a rifle with fixed chamber/throat/bore relationship where the gun aligns the bullet, but not in a revolver where the bullet is aligning the parts of the gun.
If you have a bullet that's a few thousandths larger than groove diameter and doesn't have enough breaks in the driving surfaces, the whole bullet is bound to flow some. But we don't want that, do we? We want deep, straight-sided lube grooves and crimp groove so that the alloy can displace right at the surface as it squeezes into the barrel and takes the land impression without the whole bullet extruding .
I have an idea. Cast some bullets with more antimony and tin. You have a lathe. Make a collet to hold your bullets, and turn some with one or two narrow, square relief grooves in the nose.
I think you're getting closer to finding why this bullet type never worked well for me. Not sure why it worked so well for Rick, maybe his throats were closer to groove size and his bullets got worked less.
Yes, my FA groove diameter is within tenths of a thou of all 5 throats, so close it's hard to measure. That's why again I suggested slugging the bore and be sure to check for thread choke. Not to sure any relief grooves cut in the nose will do much with this because I think the bullet is shortening from the base, not the nose down. I also think the load is still too hot for the bullet weight but if he would use the 445 brass I've been trying to get him to use that would be a big help. I suggest he use a couple of different loads with the 445 brass loaded with 20.5 gr and 21.0 gr H-110 with the same bullets. Don't be changing up a bunch of stuff at once because if it's better, worse, the same what caused it?
Based on no reports of any leading at the forcing cone or first inch or so of the bore I'm hoping that groove diameter and throat diameter are a good match. We will have to wait to see if brad will do this and give us a complete set of measurements.
I always size to the throats but I also always measure a bore slug for groove diameter, not to size to groove diameter but to know that the two are matched well. If the groove diameter is larger than the throats you will either get leading down the bore or open the throats. If the groove diameter is very much smaller than the throats my choice would be to get rid of the revolver or shoot wuss loads.
At this point from what we know so far I still think the load is too hot.
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I always size to the throats but I also always measure a bore slug for groove diameter, not to size to groove diameter but to know that the two are matched well. If the groove diameter is larger than the throats you will either get leading down the bore or open the throats. If the groove diameter is very much smaller than the throats my choice would be to get rid of the revolver or shoot wuss loads.
At this point from what we know so far I still think the load is too hot.
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fiver
Well-Known Member
I have been sitting here looking at the picture.
IMO he has enough room for the metal to displace to.
I made a couple of suggestions in a PM.
one was to harden up the alloy and the second was to harden up the lube.
lowering the load could help, and would be the way I would approach this to begin with.
when I started running things hard in the lever guns I started down at the bottom.
with clay's.
then moved to slower and slower powder speeds, eventually I hit the wall then made a slight change and another step, another change and another step.
this pretty much got me what I was gonna get with my alloy for the specific application I had in mind.
accuracy,speed, and hunting.
it also explains why I have a 10 lb LEE pot sitting next to my 40 lb magma pot.
it's easier to throw 2 lbs of this in with 4 lbs of that and make up 75 bullets to give me a trial batch.
IMO he has enough room for the metal to displace to.
I made a couple of suggestions in a PM.
one was to harden up the alloy and the second was to harden up the lube.
lowering the load could help, and would be the way I would approach this to begin with.
when I started running things hard in the lever guns I started down at the bottom.
with clay's.
then moved to slower and slower powder speeds, eventually I hit the wall then made a slight change and another step, another change and another step.
this pretty much got me what I was gonna get with my alloy for the specific application I had in mind.
accuracy,speed, and hunting.
it also explains why I have a 10 lb LEE pot sitting next to my 40 lb magma pot.
it's easier to throw 2 lbs of this in with 4 lbs of that and make up 75 bullets to give me a trial batch.
An alloy change may well be in the works as I've already suggested but I'd rather not see wholesale changes, would never know what worked and what made it worse.
I'll not be commenting on lube changes with the three lube gurus, each of you knows more about lube than I ever will so I'll leave that part it of it to you guys.
I'll not be commenting on lube changes with the three lube gurus, each of you knows more about lube than I ever will so I'll leave that part it of it to you guys.
Ian
Notorious member
This is, of course, speculation: I think his grooves collapsed because the whole bullet was pressurized (nose crunching down, base getting kicked, point having static inertia, all this happening at once), so when the lube had an opportunity to depart in the cylinder gap/forcing cone space, it did so and the metal just flowed in. There's no telling how much the bullet swelled up as it departed the cylinder and entered the forcing cone area, but the barrel swaged it back down to a bore/groove cylinder in any case.
As we've remarked, it's odd that a bullet loses its grooves, or even shrinks them, but it's pretty obvious that the bullet is under extreme pressure and instead of just elongating, it's swelling in the middle. My money is on the nose shape and size causing resistance and metal movement, which the pressure on the base works against, the two forces meet in the middle and the bullet swells up.
As we've remarked, it's odd that a bullet loses its grooves, or even shrinks them, but it's pretty obvious that the bullet is under extreme pressure and instead of just elongating, it's swelling in the middle. My money is on the nose shape and size causing resistance and metal movement, which the pressure on the base works against, the two forces meet in the middle and the bullet swells up.
Ian
Notorious member
Agreed, one thing at a time. Lube isn't his problem, anyway.
I just have one question: What, exactly, are we trying to correct by changing the alloy, and by what mechanism?
I'm hoping once the H-110 loads are tested he will take the suggestion of N-110. He's not looking for velocity with this load, it's not a hunting load, strictly long range accuracy.
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Ok.
445 brass with lower charges and same bullets
Higher Sb and Sn alloy can be done easily too.
Changing powder and primers will wait a little while I change up alloy a little.
I have H110, 2400, N110, 4227 and even some AA9 I can try. The 1680 I have is a bit slow for this case size but would certainly reduce pressure spike.
I will make a list of permutations to try. One change at a time. Need to see what happens with each change so I can see what is really going on.
This last load was much more mild to shoot than the previous load. Recoil and report was significantly reduced.
I may be able to get out tomorrow AM. If I can I will shoot reduced loads.
445 brass with lower charges and same bullets
Higher Sb and Sn alloy can be done easily too.
Changing powder and primers will wait a little while I change up alloy a little.
I have H110, 2400, N110, 4227 and even some AA9 I can try. The 1680 I have is a bit slow for this case size but would certainly reduce pressure spike.
I will make a list of permutations to try. One change at a time. Need to see what happens with each change so I can see what is really going on.
This last load was much more mild to shoot than the previous load. Recoil and report was significantly reduced.
I may be able to get out tomorrow AM. If I can I will shoot reduced loads.