This article was written by the late CBA member, Ed Donnan and appeared in the Sept/Oct 1995, #117 issue of the Fouling Shot.
I spent the winter of 1993-1994 building a "Schuetzen" rifle on a Thompson Contender pistol action. This was to be strictly an offhand rifle. I have built many rifles on the TC action but, other than a . 22 long rifle and a .17 Mach IV, none of them ex:htlJited exciting accuracy. I was willing to accept 2 minutes of angle as about all I was going to get. Two minutes is more than adequate for my level of offhand shooting.
I have read and re-read Mann's The Bullet's Flight for years, and it seems that every time I read it I gain a little gem of information or find something else to question. I believe Mann knew exactly what he was writing about, but he had great difficulty communicating with ordinary mortals such as myself There is one passage where he states unequivocally that bore size (not groove) bullets always shot best in his tests. This statement seems to fly in the face of current cast bullet knowledge. Mann also states that sizing the bullet is detrimental to accuracy. I think we pretty much agree on that. What Mann didn't know, or if he did he didn't make it clear, was that "bumping" or expanding the bullet up is not harmful to accuracy.
Mann breech seated his very soft, bore-size bullets on top of the rifling. I think he was relying on breech pressure to bump them up to groove diameter. In my design I wanted to try a bullet with very little groove contact; the bullet would be centered by the tops of the lands. However, since I was not going to use a mechanical breech seater, and because of the throat design, I was forced to add a base-band of .358" and a mid-band of .357" to my bullet. I ended up with a very conventional leade fit but I did eliminate the bullet sizing operation.
The Clymer .357 Herrett reamer has a very long leade, actually intended to be freebore with a jacketed pistol bullet. I use a case with a brass insert as a seating tool and push the bullet into the freebore ahead of the case with just thumb pressure. The fit of the bullet to the leade is half-way between fixed ammo and the single shot breech seating method. The bullet is out of the case with the nose on top of the rifling. The full .358" portion of the bullet is in the free bore. The best of both worlds - or perhaps the worst?
I spent the winter of 1993-1994 building a "Schuetzen" rifle on a Thompson Contender pistol action. This was to be strictly an offhand rifle. I have built many rifles on the TC action but, other than a . 22 long rifle and a .17 Mach IV, none of them ex:htlJited exciting accuracy. I was willing to accept 2 minutes of angle as about all I was going to get. Two minutes is more than adequate for my level of offhand shooting.
I have read and re-read Mann's The Bullet's Flight for years, and it seems that every time I read it I gain a little gem of information or find something else to question. I believe Mann knew exactly what he was writing about, but he had great difficulty communicating with ordinary mortals such as myself There is one passage where he states unequivocally that bore size (not groove) bullets always shot best in his tests. This statement seems to fly in the face of current cast bullet knowledge. Mann also states that sizing the bullet is detrimental to accuracy. I think we pretty much agree on that. What Mann didn't know, or if he did he didn't make it clear, was that "bumping" or expanding the bullet up is not harmful to accuracy.
Mann breech seated his very soft, bore-size bullets on top of the rifling. I think he was relying on breech pressure to bump them up to groove diameter. In my design I wanted to try a bullet with very little groove contact; the bullet would be centered by the tops of the lands. However, since I was not going to use a mechanical breech seater, and because of the throat design, I was forced to add a base-band of .358" and a mid-band of .357" to my bullet. I ended up with a very conventional leade fit but I did eliminate the bullet sizing operation.
The Clymer .357 Herrett reamer has a very long leade, actually intended to be freebore with a jacketed pistol bullet. I use a case with a brass insert as a seating tool and push the bullet into the freebore ahead of the case with just thumb pressure. The fit of the bullet to the leade is half-way between fixed ammo and the single shot breech seating method. The bullet is out of the case with the nose on top of the rifling. The full .358" portion of the bullet is in the free bore. The best of both worlds - or perhaps the worst?
The most noticeable innovation is the very shallow grease groove on the bullet. From studies by Mann and computer models by Andrew Barniskis, we know how a bullet expands in the leade. Deep grease grooves have always looked like a potential weakness to me, and the nearer they are to the base of the bullet the greater the potential for problems. Deep grooves near the base may allow an unsupported area to collapse non-uniformly, causing out of square bases and subsequent flyers. It would seem that if you must have deep grooves they should be near the front third of the bullet where they will do the least harm.
A 16 lb .. 357 Herrett Rifle built on a Thompson Contender pistol action
Not everyone agrees with this theory. Bob Sears and other notable experts have told me that a sizable groove near the base is necessary as a gas seal With a bullet that is not a snug fit in the leade that may be true. Early cast bullet designs such as the Lyman 311284 have deep grease grooves; perhaps with the lubes used in 1905 they were necessary. Over the years shooters have come to expect deep grooves in cast bullets and that is how the manufacturers make them Deep lube grooves are not necessary. Experiments run by Tom Gray show that most cast bullet shooters are using was too much lube. He has shown that with modem lubes, loads in excess of 2,200 :fps can be shot with as little as 3/10 of a grain of lube. More is not always better. Lets face it, bullet lube is a contaminate and we wouldn't be using it if it wasn't absolutely necessary.
I don't believe there is any reason for lube to remain on the bullet past the end of the barrel. While scoring I 00-yard targets I have seen blue lube spattered around bullet holes and have occasionally seen the same thing on targets fired at 200 yards. Obviously the lube stayed on the bullet all the way to the target. True, this did not appear to do any great harm, but it is hard to believe that lube on the bullet contributes anything good to its external ballistics. We would not have any grease grooves on our bullets if they were not needed. In my research I encountered a couple of interesting failures of non-grooved bullets. One, In the NRA Publication Cast Bullets, deals with the development of paper patched bullets and the other with bullet lubes under the base of the bullet.
Author and his rifle
The latter experiment failed when bullets without grooves were used. While neither experiment was directly related to what I was trying to do, and no one was even willing to venture a guess as to why they failed, I took this information under advisement and decided to use a lube groove of bore diameter (.350").
I used a rather simple method to produce the mould. A half reamer with the bullet nose form and base on it was made in a lathe. A junk, small block Lyman 6mm mould was indicated in a four-jaw chuck and roughed out using common drills. The reamer produced the main form of the mould cavity, and a second band was added using a small boring bar. The half-reamer cuts very well on its side, but doesn't like to bore with its nose. My reamer cut beautifully until it started to make a full cut.
Bullets cast of 12 BHN scrap alloy measure .3585" on the base band, .3570" on the middle band and .3515" on the nose. I meant to make the nose .3505" but, with the soft alloy, engraving another .0015" with thumb pressure is not a problem. The other dimensions are just about perfect for the leade.
I have never used a mould that drops its bullets as easy as this one does; probably because of the shallow grease groove. Usually the bullet drops when I open the handles. Initially I used the original Lyman sprue plate but was plagued with rounded bases and tears in the sprue cut-off. After casting about 100 bullets I made another sprue plate with a .125" pour hole out of W' aluminum stock. This solved the problem, producing sharp base edges and clean cutoffs. I would like to say the modification produced a big increase in accuracy - it did not - but it make me feel better.
I anticipated that, using the small Lyman blocks for a 295 gr .. 35 cal. bullet, the blocks would soon over-heat. This is not the case. In fact, the blocks tend to run cold and have a very small "casting window". You have to cut the sprue about 3 to 31/z seconds after it changes color. If you wait longer the next bullet is sure to have a rounded base. The sprue sets up rather quickly. There is just enough time to inspect the last bullet cast and throw the cut-off sprue into the pot before the next sprue hardens. This precludes casting with two moulds.
I used a rather simple method to produce the mould. A half reamer with the bullet nose form and base on it was made in a lathe. A junk, small block Lyman 6mm mould was indicated in a four-jaw chuck and roughed out using common drills. The reamer produced the main form of the mould cavity, and a second band was added using a small boring bar. The half-reamer cuts very well on its side, but doesn't like to bore with its nose. My reamer cut beautifully until it started to make a full cut.
Bullets cast of 12 BHN scrap alloy measure .3585" on the base band, .3570" on the middle band and .3515" on the nose. I meant to make the nose .3505" but, with the soft alloy, engraving another .0015" with thumb pressure is not a problem. The other dimensions are just about perfect for the leade.
I have never used a mould that drops its bullets as easy as this one does; probably because of the shallow grease groove. Usually the bullet drops when I open the handles. Initially I used the original Lyman sprue plate but was plagued with rounded bases and tears in the sprue cut-off. After casting about 100 bullets I made another sprue plate with a .125" pour hole out of W' aluminum stock. This solved the problem, producing sharp base edges and clean cutoffs. I would like to say the modification produced a big increase in accuracy - it did not - but it make me feel better.
I anticipated that, using the small Lyman blocks for a 295 gr .. 35 cal. bullet, the blocks would soon over-heat. This is not the case. In fact, the blocks tend to run cold and have a very small "casting window". You have to cut the sprue about 3 to 31/z seconds after it changes color. If you wait longer the next bullet is sure to have a rounded base. The sprue sets up rather quickly. There is just enough time to inspect the last bullet cast and throw the cut-off sprue into the pot before the next sprue hardens. This precludes casting with two moulds.
left- 295 grain .35 cal. bullet as-cast; right- fired bullet recovered
When shooting this bullet the first thing that became apparent was that bullet hardness had little to do with accuracy. Remember the bullet is seated in the leade, not in the rifling. rm not a single shot shooter but, from what I've read, I expected bullet hardness to be critical. Sure, I tried linotype bullets; I tried pushing them fast and promptly leaded the bore. If I held the velocity under 1400 fps, 8 to 22 BHN bullets produced about equal accuracy with a slight adjustment of the powder charge. I don't know if this effect is produced by the bullet design, seating the bullet in the leade, or an idiosyncrasy of this particular barrel.
I tried Red Dot powder at first but had erratic flyers. From previous experiments I knew that Blue Dot worked well in this type of application and had immediate success when I tried it. I have not done much experimentation with different powder, there very well might be a better choice.
I tried Red Dot powder at first but had erratic flyers. From previous experiments I knew that Blue Dot worked well in this type of application and had immediate success when I tried it. I have not done much experimentation with different powder, there very well might be a better choice.
From the bullet design you might think lube would be a critical factor. For years my standard of comparison has been the NRA beeswax/alox formula. Of course it was the first thing I tried simply smearing it over the bullet with my finger tips. I also tried Lee Liquid Alox, Tom Grays experimental #24, and several other commercial lubes I had on hand. All of the lubes left a neat lube star on the muzzle and accuracy was about the same, as was bore condition. Very thin coats of lube were used, in fact you could not see the color ( except for the Lee) on the bullet. There were no apparent failures due to insufficient lube. There were some accuracy failures generated by applications of two different lubes ( chassis lube on top of Lee Alox) and over lubing the bullet.
As I stated, I was trying to build a 2 MOA off hand rifle. From the very start it was evident the rifle was going to shoot better than that. We have all heard about problems with two-piece stocks. Well, my rifle not only has a two piece stock but also a two-piece action. Its not just twice as bad, its more like a squared function. Cranky? It's crankier than my wife two days before payday.
I had just shot a 10-shot group at 200 yards that was round and measured 21h11 and thought I would try the free-recoiling method. Five shots free recoiling went into more than 12". I then fired five shots using the heavy cheek and shoulder pressure used for the first group; those shots went under 2". Evidently the heavy hold on the rifle forces the action and barrel into the same alignment every time. Doubt this? Take your favorite TC, clamp the frame in a vise, then move the barrel. Depressing isn't it? The frame of my action is old and worn and has seen many rounds and barrels. Seeing how much movement there was, I gave the frame a judicious squeeze in an aluminum jawed vise and removed about 95% of the play. Still, the rifle has to be held hard to shoot well.
Despite what might be considered rough handling, the rifle shows signs of amazing accuracy. Late evening testing at 200 yards has produced many five to seven-shot clusters in the .5 to .75 MOA category. Unfortunately they were part of ten-shot groups that ended up being around 1 to 1 Vi MOA More often than not these extremely small partial groups were successive shots.
Because the rifle is heavy and recoil light, if the light is right you can often watch the bullet in flight for the last 20 yards or so. It is an exhilarating experience to watch the bullet drop into the last hole. You become convinced that if you held your mouth just right they would all go in. Even when you think you are holding the rifle the same way you can sometimes feel a difference in the recoil. You can rest assured that if the recoil felt different, the shot opened up the group.
In a large part my experiment was generated by expedience. The .357", 1-16" Douglas barrel was what I had in the shop. The .357 Herrett reamer was also what was on hand. Given a choice I think the .357 Max would have been better. Nevertheless, I deem the project a success as it caused me to work on bullet design. This is a field that has been sadly neglected until the last few years.
I consider my efforts successful. The rifle is twice as accurate as I had hoped it would be. I have learned that because of bullet design, a plain base and a shallow grease groove, the mould throws the bullets out like popcorn. Also, for whatever reason, it appears the bullet has a high tolerance for both different lubes and varying degrees of hardness. I don't think that I've proved that my design is vastly superior to more conventional bullets, however the design does work, proving that some of the principals held dear for almost a hundred years are not necessarily carved in stone. @
As I stated, I was trying to build a 2 MOA off hand rifle. From the very start it was evident the rifle was going to shoot better than that. We have all heard about problems with two-piece stocks. Well, my rifle not only has a two piece stock but also a two-piece action. Its not just twice as bad, its more like a squared function. Cranky? It's crankier than my wife two days before payday.
I had just shot a 10-shot group at 200 yards that was round and measured 21h11 and thought I would try the free-recoiling method. Five shots free recoiling went into more than 12". I then fired five shots using the heavy cheek and shoulder pressure used for the first group; those shots went under 2". Evidently the heavy hold on the rifle forces the action and barrel into the same alignment every time. Doubt this? Take your favorite TC, clamp the frame in a vise, then move the barrel. Depressing isn't it? The frame of my action is old and worn and has seen many rounds and barrels. Seeing how much movement there was, I gave the frame a judicious squeeze in an aluminum jawed vise and removed about 95% of the play. Still, the rifle has to be held hard to shoot well.
Despite what might be considered rough handling, the rifle shows signs of amazing accuracy. Late evening testing at 200 yards has produced many five to seven-shot clusters in the .5 to .75 MOA category. Unfortunately they were part of ten-shot groups that ended up being around 1 to 1 Vi MOA More often than not these extremely small partial groups were successive shots.
Because the rifle is heavy and recoil light, if the light is right you can often watch the bullet in flight for the last 20 yards or so. It is an exhilarating experience to watch the bullet drop into the last hole. You become convinced that if you held your mouth just right they would all go in. Even when you think you are holding the rifle the same way you can sometimes feel a difference in the recoil. You can rest assured that if the recoil felt different, the shot opened up the group.
In a large part my experiment was generated by expedience. The .357", 1-16" Douglas barrel was what I had in the shop. The .357 Herrett reamer was also what was on hand. Given a choice I think the .357 Max would have been better. Nevertheless, I deem the project a success as it caused me to work on bullet design. This is a field that has been sadly neglected until the last few years.
I consider my efforts successful. The rifle is twice as accurate as I had hoped it would be. I have learned that because of bullet design, a plain base and a shallow grease groove, the mould throws the bullets out like popcorn. Also, for whatever reason, it appears the bullet has a high tolerance for both different lubes and varying degrees of hardness. I don't think that I've proved that my design is vastly superior to more conventional bullets, however the design does work, proving that some of the principals held dear for almost a hundred years are not necessarily carved in stone. @