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Post by Bullshop on Jan 12, 2016 21:42:13 GMT -7
The question of weather heeled bullets are inherently accurate has recently come up so I would like to offer some of my thoughts on the subject. In the old day when smokeless powder was new the target shooters of the day seemed to agree that the best diameter for cast bullets was groove diameter or even slightly under. The reason it was believed is that bullets larger than groove diameter would become unbalanced from finning at the base by the metal being displaced from the land impressions into the bullet. I have witnessed this finning as it was called on bullets larger than groove diameter of the barrel they were fired in. Close inspection of bullet bases of flat base bullets either cast or jacketed sometimes show at the land cuts at the bullet base the displaced metal extending past the bullet base. These fin extensions are seldom even around the base but almost always longer on one side than the other. This seems to confirm that there was indeed some truth or at least some substance to what was believed at the time. Now let us jump to the present when the common belief is that best accuracy comes from bullets that are .001" to .003" over groove diameter. On average today cast bullets are harder and of different alloys than of yesteryear. The old timey shooters used mostly binary alloys of lead and tin in different ratios. Today almost all alloys used for smokeless powder loadings contain antimony which changes the character of the alloy. Where the softer binary alloy depended on obturation to make a gas seal the harder alloys we use today seem to depend more on bullet diameter so we tend to run bullet diameter a bit over barrel groove diameter. This makes me wonder about the finning that was believed to effect accuracy. This may be more pronounced on plain base bullets but I have seen it on gas checks as well. I don't think that anyone will disagree that it is well accepted that the bullet base is the steering end of a bullet . Its seems also well accepted that a buggered up bullet nose may have little effect on accuracy but a buggered up base is a waste of time. With that in mind lets take a look at the heeled base like on a 22 rim fire. On such a configuration if any finning is occurring it is on the full diameter band just ahead of the heeled section so not actually on the bullet base. Because the heel is closer to bore diameter not groove diameter it is not being cut or more properly impressed by the lands but just riding on them. I have run these things through my mind so many times and come to this point where I think there may well be something about heeled bullets that may well make them inherently more accurate than flat base bullets. Of course I am talking about cast bullets but there may well be something closely associated with this idea with jacketed bullets between flat base and boat tail designs. A boat tail would essentially have the same effect as a heel putting and finning ahead of the bullet base proper. This is surely another area of testing that is open for anyone that has the time. Right now I don't because I still need to do much more shooting to come to some firm conclusions on another subject dealing with cast bullets that being can gas check cast bullet designs shoot as well without the gas check as with, and a second part of that question at what velocity. That being closely related to this diatribe because a gas check base design without the gas check is essentially a heeled base so the end of one trail of testing may be the beginning of another Anyway there you have a glimpse into where my mind goes for all those hours I spend casting. Once I am satisfied that I have taken the other current subject of testing as far as I can I hope to explore this subject a bit. So much shooting to do and so little time.
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Post by todddoyka on Jan 13, 2016 13:35:23 GMT -7
i did much the same thing, i purposely "buggered" up a few bullets in the nose section and the base. the nose did little to affect accuracy. the base did. i was shooting a 30-06 at the time and i think it was written by petersen's hunting magazine. i don't remember the author...could have been bodington, sitton, wootters.. it was 20+ years ago. anyhoo i decided to mess up a few bullets to see if they were right. the bullets were cut by a folding pocket knife, nose was disfigured and on another bullet the base was disfigured. i shot the nose section(i think it was 150gr hornady sp) and the accuracy was normal. i don't know about 300+yards but at 100 yards it really didn't matter. then i shot the disfigured base bullet. accuracy was dismal. when the bullets hit the paper it looked as if i punched them threw sideways. that was about all i needed to know. nose good, base bad. now i do have a 22rf that i would take the bullets(40gr don't mater which one, remmys, federal...) and put it in a homemade jig and then file off the nose to make a flat point. they worked great for hunting!!! but i did have a problem with my 22rf. it is a marlin 15y with microgroove barrel(mid 1980's). i was one of those guys that had to clean the barrel everytime i would shoot. i was 13 or 14 years old so i did. oil and hoppes became rare at my house. then one day i decided not to clean the barrel, just the outside. i noticed around 100-150 shots, my groups began to shrink. i went from 1 1/2" at 50 yards to 3/8" at 50 yards. needless to say, the 22rf does NOT get cleaned until the chamber doesn't fit the cartridge anymore! this has been going on for 30 years. i clean the barrel every 2 or 3 years, but when i'm done i immediatly shoot 100-150 rounds out of it. my guess(look out, i'm guessing!!!  ) is that my barrel is overbored. i know its not hard to slug the bore but i'm lazy and the 150 shots are fun!! the 100-150 shots are basically just to put crud(lotta lead and some burned powder) into the bore. but since the price of 22rf has gone up(used to be 500 for $17, now its 500 for $42.50) i don't get to shoot it as much. there might be something to heeled bullets on accuracy. mmmmmm gives me something to think about!!!!  |
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Post by todddoyka on Jan 13, 2016 14:09:49 GMT -7
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Post by markus on Jul 11, 2020 14:59:36 GMT -7
"I still need to do much more shooting to come to some firm conclusions on another subject dealing with cast bullets that being can gas check cast bullet designs shoot as well without the gas check as with, and a second part of that question at what velocity". (bullet Master on January 12 2016
I am wondering sir, were you able to come to any conclusions on this?
Thanks
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Post by Bullshop on Jul 11, 2020 17:47:13 GMT -7
Yes Sir I believe we were. Those were that when a gas check is not needed such as in loads developing less than 1500 fps we saw what seemed to be an accuracy improvement without gas checks. On the other hand when velocity exceeded that 1500 threshold area using gas checks gave best results.
This seems to show that if we keep our smokeless powder loads within the normal black powder range about 1300 fps average then gas checks are absolutely not needed and possibly more accurate without them even with bullets designed to use them.
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Post by markus on Jul 11, 2020 22:31:16 GMT -7
Awesome. Thanks for the direct and clear response. Fortunately that fits with something an old time reloader and voracious reader on the subject (my dearly departed dad) once mentioned and I vaguely recall, regarding the use of gas checks and accuracy with hot handgun loads.
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Post by missionary on Jul 12, 2020 5:56:10 GMT -7
So still the issue of bullet mix has me wondering.
My little ponderings have been with the shooting of a 41 Colt New Army with a 6" barrel. I bought the revolver because one it is a 41 (almost) and it was the nicest old Colt (90-95 %) I was ever in company with that also was very affordable.
In the beginning brass and bullets were not available so we adapted 38 special brass (wraps of asking tape) and caliber .358 158 grain SWC slugs cast of range scrap. These were bumped up in a vice bringing the nose to a snug fit in the 38 brass and then the body passed through a hoe drilled / honed sizer to cylinder diameter of .407 average. Just to clarify bullet was loaded squeezed nose first into the 38 case.
Empty space was filled with 3F so it was compressed about 1/8".
This load fired great and was soda an accurate out to 20 yards. Recovered slugs showed heeled section expanding to almost cylinder dimeter and being imprinted with riffling.
The same load fired with Unique starting at 3 grains and up to 6 grains were not as accurate and the heel never expanded to near cylinder size and never engraved.
I also dropped the 6 grain Unique load as the recoil was far more than the 3F loads produced. 5 grains was the near equal.
So as of today when we shoot the 41 Colt it is only with 3F. With a 200 grain slug cast of 40-1 or even range scrap it is not what I would want someone launching at me at 25 yards or less. This is with 41 Colt brass also. I do not remember how much 3F but it is enough to get compressed 1/8" with a cereal box wad under the bullet. 45-55% olive oil - beeswax lube hot dipped on the nose or just smeared on the nose before loading.
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Post by Bullshop on Jul 12, 2020 10:43:17 GMT -7
Regardless of weather or not a gas check is used the bullet alloy hardness should still be well mated to the chamber pressures being loaded to. A very simple formula to get you ball park close is BHN X 1900 = chamber pressure in psi.
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) is that my barrel is overbored. i know its not hard to slug the bore but i'm lazy and the 150 shots are fun!! the 100-150 shots are basically just to put crud(lotta lead and some burned powder) into the bore. 
