johnnyjr
Well-Known Member
Wonder what alloy they used..
Plain Base Cast bullets ( Rifle) observation!
- Thread starter JWFilips
- Start date
Most likely they paid from little to no attention to BHN and a great deal of attention to the FIT in the rifle. Most likely a fairly soft alloy such as 20/1.
I m going to do this backwards this time - post, THEN read all the other comments. I'm doing this to exclude my observation/assertion from being subject to what I've read. This very topic has been on my mind lately and I read a lot of wisdom regarding it, but I'm not seeing a solid basis for a certain hypothesis, which I may be misunderstanding anyway.
I've dug a lot of golf-ball-sized conglomerations of bullets out of my back stops over the years, indicating to me that they are all going into a pretty tight group. One thing I've noticed about them is that the plain bases have ALL shown little "tails" betraying the deformation and displacement caused by the lands of the rifling.
If the perfect base is so important, and it gets ruined right at the muzzle, where it's supposed to count for so much, then WHY are these same (deformed) bullets going into such tight clusters as to form golf-ball-sized conglomerations of bullets in the back stop?
My brain tells me that this should ruin my accuracy, as the expanding gasses begin to escape past the first opening presented by the exiting bullet. My brain tells me that if this escape route is not evenly distributed about t he circumference of that the bullet, then could be tipped one way or another by the first jet of gas which escapes. My eyes disagree with my brain and I'm expected to referee this discord, but I don't even know what to say. I believe my eyes, I agree with my brain.
What I WILL say is that I'm not buying the bevel base or boat-tail being a remedy to this "problem," because all it does is cause the SAME THING ("problem") to happen - it just happens before the base gets to the muzzle. The escaping gas does not wait for the base to show up at the muzzle. It's going to escape at its first opportunity and does so at the front edge of the bevel or boat-tail - or wherever the last part of the full-diameter of the bullet is located on that bullet. The SAME THING is going to happen - gas will escape at the first opportunity and it will NOT necessarily be even along the circumference of the full-diameter portion of the bullet - the very last part of which may be at the base, on a plain-base, or farther forward, at the front edge of a bevel or a boat-tail.
Haven't shot any boat tails, but I've shot a bunch of bevel-bases and the bullet metal still displaces, and a fair bit of it displaces to the rear, always making the circular edge which "breaks" the muzzle UNEVEN.
NOW, having stuck my neck out, I will go back and read the other posts and see if anyone else has come to the same conclusion or can shed some light on my dim wit.
I've dug a lot of golf-ball-sized conglomerations of bullets out of my back stops over the years, indicating to me that they are all going into a pretty tight group. One thing I've noticed about them is that the plain bases have ALL shown little "tails" betraying the deformation and displacement caused by the lands of the rifling.
If the perfect base is so important, and it gets ruined right at the muzzle, where it's supposed to count for so much, then WHY are these same (deformed) bullets going into such tight clusters as to form golf-ball-sized conglomerations of bullets in the back stop?
My brain tells me that this should ruin my accuracy, as the expanding gasses begin to escape past the first opening presented by the exiting bullet. My brain tells me that if this escape route is not evenly distributed about t he circumference of that the bullet, then could be tipped one way or another by the first jet of gas which escapes. My eyes disagree with my brain and I'm expected to referee this discord, but I don't even know what to say. I believe my eyes, I agree with my brain.
What I WILL say is that I'm not buying the bevel base or boat-tail being a remedy to this "problem," because all it does is cause the SAME THING ("problem") to happen - it just happens before the base gets to the muzzle. The escaping gas does not wait for the base to show up at the muzzle. It's going to escape at its first opportunity and does so at the front edge of the bevel or boat-tail - or wherever the last part of the full-diameter of the bullet is located on that bullet. The SAME THING is going to happen - gas will escape at the first opportunity and it will NOT necessarily be even along the circumference of the full-diameter portion of the bullet - the very last part of which may be at the base, on a plain-base, or farther forward, at the front edge of a bevel or a boat-tail.
Haven't shot any boat tails, but I've shot a bunch of bevel-bases and the bullet metal still displaces, and a fair bit of it displaces to the rear, always making the circular edge which "breaks" the muzzle UNEVEN.
NOW, having stuck my neck out, I will go back and read the other posts and see if anyone else has come to the same conclusion or can shed some light on my dim wit.
RicinYakima
High Steppes of Eastern Washington
You are correct and we have known this since the 1970's. Muzzle crown condition has very little to do with shooting groups, but a lot to do with point of impact. This was a hot subject in the 1970's and many experiments were done, and all reached the same conclusion. Low SD number will make groups look smaller, but it is a point of impact shift.
The secondary function of lube grooves is to have a home for displaced metal from the lands. Bevel or boattail doesn't make any difference, the volume of the lands will displace the bottom band's metal at the back of the bullet.
There was a theory that the fins broke off unevenly after a certain velocity was reached so to disrupted airflow and unbalance. Never saw a really good experiment about this guess.
This has been one of my primary rationalizations for sticking with lube grooves, even after I started tumble-lubing pretty much everything. I have also noticed that on most of the "micro-groove" bullets (LEE or otherwise) with a short bottom band and ever-so-slightly rounded base that this base-finning is mitigated to a great extent - whether it has much to do with anything or not.
Ian
Notorious member
Two things to consider, Jeff.
One, if (whatever it is) happens evenly, all the way around, at the muzzle, it doesn't affect consistency (or, more correctly we should say, repeatability) of the POI.
Two, there is a big difference between the little "tails" trailing off the base and finning all the way around due to the major diameter of the bullet base being larger than the groove diameter when it went into the barrel.
My results, in a sort of general but definitely trending way, indicate that with powder coated rifle bullets from subsonic to about the accurate limit of the systems, groups are invariably better with checkless gas check bullet designs, boat tails, bevel bases, and even bullets deliberately cast with a cold sprue plate to yield rounded bases than with bullets having crisp, clean, full-diameter, flat bases.
One, if (whatever it is) happens evenly, all the way around, at the muzzle, it doesn't affect consistency (or, more correctly we should say, repeatability) of the POI.
Two, there is a big difference between the little "tails" trailing off the base and finning all the way around due to the major diameter of the bullet base being larger than the groove diameter when it went into the barrel.
My results, in a sort of general but definitely trending way, indicate that with powder coated rifle bullets from subsonic to about the accurate limit of the systems, groups are invariably better with checkless gas check bullet designs, boat tails, bevel bases, and even bullets deliberately cast with a cold sprue plate to yield rounded bases than with bullets having crisp, clean, full-diameter, flat bases.
@Ian , my general observations have trended similarly. This was one of those things which never seemed to be an issue, but I eventually started reading more about people's concerns and ominous hypotheses regarding the matter. OK, so maybe I don't shoot far enough or fast enough that it makes a difference?
But that bevel-based or boat-tail bullets were the "cure,".... Didn't make sense to me.
I have yet to shoot any of the bullets I've PC'd from a rifle, other than the 357 Mag. I have a bunch of 22s and 30s for the 222 and 30/30 to try one of these days, but I've put a bunch of TL'd stuff through them.
@fiver , my gas checks, especially the 22 cal ones, don't have very square edges, but they are consistent all 'round AND, they do leave that little void for the displaced bullet metal to collect in. I've long thought that to, at the very least, not be a disadvantage.
But that bevel-based or boat-tail bullets were the "cure,".... Didn't make sense to me.
I have yet to shoot any of the bullets I've PC'd from a rifle, other than the 357 Mag. I have a bunch of 22s and 30s for the 222 and 30/30 to try one of these days, but I've put a bunch of TL'd stuff through them.
@fiver , my gas checks, especially the 22 cal ones, don't have very square edges, but they are consistent all 'round AND, they do leave that little void for the displaced bullet metal to collect in. I've long thought that to, at the very least, not be a disadvantage.
fiver
Well-Known Member
well some guys helped me when i sent them some bullets with rounded corners on the GC shanks, and gave me all kinds of advice on how to make them better.
the only one that didn't was the one that got them checked and lubed with load data and shot them at 500yds.
it isn't easy to get those corners all the same.
the only one that didn't was the one that got them checked and lubed with load data and shot them at 500yds.
it isn't easy to get those corners all the same.
RicinYakima
High Steppes of Eastern Washington
Spindrift
Well-Known Member
I have some bullet designs available in both GC and PB format, like the NOE #315- clone.
I've done some comparative accuracy testing with coated bullets, comparing PB and checkless bullets. Results were much the same. But the number of groups was not enough to really draw any firm conclusions.
I'll have to look into that again!
I've done some comparative accuracy testing with coated bullets, comparing PB and checkless bullets. Results were much the same. But the number of groups was not enough to really draw any firm conclusions.
I'll have to look into that again!
Snakeoil
Well-Known Member
This thread could not come at a better time. As you know, I'm working on getting my .32-40 to shoot with PB bullets. I'm a total neophyte to this topic. But between a few of us at Wilton, all shooting single shots in straight-wall BP cases and using smokeless have seen some trends appear. The most striking so far as been the softness (I think this is the more appropriate term in this case) of the alloy.
I started out with 20:1. It's what I used with my .45-70 Shiloh Sharps with a PB Paul Jones bullet. I shot decent with that combination, but never had a partner that taught me much. Wind and mirage were all new to me, iron sight added another variable so it is impossible to say if I could have done better because of simple factors like better condition calls.
I continued with 20:1 for my 03 with GC bullets. Rifle shoots very well and perfect scores out to 500 yards have been achieved with a scope. Those bullets were also about 0.002 over groove diameter.
So, when I moved to PB in the .32-40, I continued on with 20:1. My bore is oversize as some of you know, so I figured I needed 0.002 over groove for that rifle. I ordered a mold and while I was waiting started shooting from borrowed molds that dropped bullets at my 0.326 groove diameter.
20:1 still shot poorly. And while this was going on, another member with a Hepburn that he had relined to .32-40 was also struggling to get his rifle to shoot. We both found indications of leading in our barrels after shooting. I lapped mine with a lead lap and JB Borepaste. He has since done the same. But both rifles continued to shoot poorly. Another member who shoots .32-40 and .25-20SS with PB bullet to great success kept telling us our bullets were too hard. I finally gave in as I had nothing to lose. I went to 30:1. The groups tightened up significantly. And leading ceased.
So, as part of the journey, I was asking others that shot the same caliber with PB bullets with success, how their bullet size compared to bore diameter. One shooter, Craig, pushed a bullet thru his barrels and gave and gave it to me. Then another member, Steve, put a primer and pinch of powder in a case and fired a bullet into a pile of rags and gave it to me. After reading all 3 pages of this thread and the linked thread from 2017 on page 1 of this thread, I took a closer look at those bullets to see what kind of displaced lead existed at the bases created by the lands, and what those tail fins looked like on the base of the bottom band. What I saw I think is significant. Here are some macro photos.
This is Craig's bullet. He pushed this thru his barrel with a rod. Said that it took very little effort. He's using 30:1 or softer.
The indent in the base is from the rod. Note however the skirt formed around the base and the scalloped effect made by the lands engraving the base driving band. I do not see anything that I would call "fragile fins" that could tear or be blown off upon exiting the muzzle. But, this bullet was pushed, not fired.
Here is another view at a slightly different angle. What I don't see is a thin fin created. The land seems to have swaged the band rather than engraved the band.
Here is a side view showing how the base band was moved rearward. Again note that it is a smooth scalloped edge, not a ragged or torn find.
Now here is Steve's bullet. Keep in mind that this was a very light charge, probably just slightly more than the powder of a primer in order to get it to exit the barrel.
Here is the base of Steve's bullet. The roughness is powder residue. There is slight deformation at the land area.
Here is a side view. In this view there is a definite scallop to the edge of the base caused by the land. But it is neither thin nor fragile looking. Also note that the two scallops visible in this photo appear to be very uniform.
So, like I said, I'm a total newbie to all this stuff. But from what I see here, it does not appear that any thin fins/tails are created by the barrel lands. I do see deformation of the bands and the bottom edge of the base, but that deformation looks uniform to me. I would think that as long as those scallops are uniform and sufficiently robust to remain in place upon exiting the muzzle, they are of little consequence.
Last point from my uniformed opinion is nobody has mentioned the fouling star on the end of the muzzle. Granted, you might not notice it on a radius crown that is blued. But on a flat muzzle that is polished, it is quite clear. If bullets had bases that were loosing pieces and allowing gas to escape on one side, I would expect to see that on the muzzle as a non-uniform star. I could understand that if pieces broke off in different areas on the circumference of the base, then that could with enough rounds fired result in a uniform start. But that would also mean that every bullet engraved differently in the rifling producing a weak fin at different clock positions on the bullet. I would think that would be the result of bullet jump. But since I am breech seating, that should not be an issue.
I started out with 20:1. It's what I used with my .45-70 Shiloh Sharps with a PB Paul Jones bullet. I shot decent with that combination, but never had a partner that taught me much. Wind and mirage were all new to me, iron sight added another variable so it is impossible to say if I could have done better because of simple factors like better condition calls.
I continued with 20:1 for my 03 with GC bullets. Rifle shoots very well and perfect scores out to 500 yards have been achieved with a scope. Those bullets were also about 0.002 over groove diameter.
So, when I moved to PB in the .32-40, I continued on with 20:1. My bore is oversize as some of you know, so I figured I needed 0.002 over groove for that rifle. I ordered a mold and while I was waiting started shooting from borrowed molds that dropped bullets at my 0.326 groove diameter.
20:1 still shot poorly. And while this was going on, another member with a Hepburn that he had relined to .32-40 was also struggling to get his rifle to shoot. We both found indications of leading in our barrels after shooting. I lapped mine with a lead lap and JB Borepaste. He has since done the same. But both rifles continued to shoot poorly. Another member who shoots .32-40 and .25-20SS with PB bullet to great success kept telling us our bullets were too hard. I finally gave in as I had nothing to lose. I went to 30:1. The groups tightened up significantly. And leading ceased.
So, as part of the journey, I was asking others that shot the same caliber with PB bullets with success, how their bullet size compared to bore diameter. One shooter, Craig, pushed a bullet thru his barrels and gave and gave it to me. Then another member, Steve, put a primer and pinch of powder in a case and fired a bullet into a pile of rags and gave it to me. After reading all 3 pages of this thread and the linked thread from 2017 on page 1 of this thread, I took a closer look at those bullets to see what kind of displaced lead existed at the bases created by the lands, and what those tail fins looked like on the base of the bottom band. What I saw I think is significant. Here are some macro photos.
This is Craig's bullet. He pushed this thru his barrel with a rod. Said that it took very little effort. He's using 30:1 or softer.
The indent in the base is from the rod. Note however the skirt formed around the base and the scalloped effect made by the lands engraving the base driving band. I do not see anything that I would call "fragile fins" that could tear or be blown off upon exiting the muzzle. But, this bullet was pushed, not fired.
Here is another view at a slightly different angle. What I don't see is a thin fin created. The land seems to have swaged the band rather than engraved the band.
Here is a side view showing how the base band was moved rearward. Again note that it is a smooth scalloped edge, not a ragged or torn find.
Now here is Steve's bullet. Keep in mind that this was a very light charge, probably just slightly more than the powder of a primer in order to get it to exit the barrel.
Here is the base of Steve's bullet. The roughness is powder residue. There is slight deformation at the land area.
Here is a side view. In this view there is a definite scallop to the edge of the base caused by the land. But it is neither thin nor fragile looking. Also note that the two scallops visible in this photo appear to be very uniform.
So, like I said, I'm a total newbie to all this stuff. But from what I see here, it does not appear that any thin fins/tails are created by the barrel lands. I do see deformation of the bands and the bottom edge of the base, but that deformation looks uniform to me. I would think that as long as those scallops are uniform and sufficiently robust to remain in place upon exiting the muzzle, they are of little consequence.
Last point from my uniformed opinion is nobody has mentioned the fouling star on the end of the muzzle. Granted, you might not notice it on a radius crown that is blued. But on a flat muzzle that is polished, it is quite clear. If bullets had bases that were loosing pieces and allowing gas to escape on one side, I would expect to see that on the muzzle as a non-uniform star. I could understand that if pieces broke off in different areas on the circumference of the base, then that could with enough rounds fired result in a uniform start. But that would also mean that every bullet engraved differently in the rifling producing a weak fin at different clock positions on the bullet. I would think that would be the result of bullet jump. But since I am breech seating, that should not be an issue.
Attachments
Ian
Notorious member
Rob, this is exactly why I don't like using bullets any larger than absolutely necessary. Another thing is engraving resistance. If it's really hard to get the bullet moving, powder pressure can get high enough to mushroom the base before it even reaches the rifle's throat. After being drawn down through the throat you can imagine what kind of condition the base is in.
Things that make engraving resistance too high are hard, brittle alloys, grossly oversized bullets, jamming the bullet when chambering, and exactly matching throat/bullet tapers which have angles that are too abrupt while parking the bullet right against that angle.
Things that make engraving resistance too high are hard, brittle alloys, grossly oversized bullets, jamming the bullet when chambering, and exactly matching throat/bullet tapers which have angles that are too abrupt while parking the bullet right against that angle.
Snakeoil
Well-Known Member
My mistake was driven out of pure ignorance from lack of experience. I had always read that 0.001 to 0.002 over groove was desired and that was the secret to getting my oversized 03 to shoot well. But that was with GC bullets. I naively applied the same theory to PB bullets and it failed.
I am about to order a mold for the .32-40 and needed more data to help me decide how I want Tom at Accurate to set the 0.002 tolerance. Yesterday I shot the same .326 bullet sized to .325 using the new die that arrived the other day. I wanted to see how 0.001 under groove would shoot. The 10 shot group measured 3" at 100 yds. It was a freshly cleaned bore and I fired 5 fouling shots before shooting for group. But what we found was the 1st shot for group and then the last 3 all grouped within about 1.125". So, it could be the gun was settling in or my eyes were getting better calibrated for the iron sights for those last 3 rounds. Regardless, it told me that going +/- 0.001 for a mold size of 0.326 will probably be the way to go.
I am about to order a mold for the .32-40 and needed more data to help me decide how I want Tom at Accurate to set the 0.002 tolerance. Yesterday I shot the same .326 bullet sized to .325 using the new die that arrived the other day. I wanted to see how 0.001 under groove would shoot. The 10 shot group measured 3" at 100 yds. It was a freshly cleaned bore and I fired 5 fouling shots before shooting for group. But what we found was the 1st shot for group and then the last 3 all grouped within about 1.125". So, it could be the gun was settling in or my eyes were getting better calibrated for the iron sights for those last 3 rounds. Regardless, it told me that going +/- 0.001 for a mold size of 0.326 will probably be the way to go.
Bevel or BT allows an earlier release of gas at the crown/muzzle. And that gas is 30% faster than the bullet. Any metal moved to the base (by friction and displacement) should be concentric so should not be a problem. Any long 'fin' probably gets blown off at the crown, gas cutting. But yes any non-concentric base will cause problems. My PB rifle bullets have a very small rebate at the base so I get nice filled out base. And easy to cull bad pours.
RicinYakima
High Steppes of Eastern Washington
Picture #3 shows the beginning of "fins" and they get more pronounced the faster the bullet. Catching the bullet in oiled sawdust will show them maybe 50% longer. Shooting with gas checks, the space between the top of the check and bottom drive band contains any finning.
Snakeoil
Well-Known Member
I'm not sure what you mean by "rebate at the base".
One of the bullets I was looking at on the Arsenal site has a slight chamfer (bevel) on the edge of the base. It is very slight, but there. I wonder if it is something that is related to Harry Pope's design. It looks like the 632 Saeco, but it not tapered. I wanted to see if they could make a tapered version, but I cannot get them to respond to emails or phone messages.
One of the bullets I was looking at on the Arsenal site has a slight chamfer (bevel) on the edge of the base. It is very slight, but there. I wonder if it is something that is related to Harry Pope's design. It looks like the 632 Saeco, but it not tapered. I wanted to see if they could make a tapered version, but I cannot get them to respond to emails or phone messages.
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