Random Lube & Fouling Ruminations

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DanTDesigns
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Re: Random Lube & Fouling Ruminations

Post by DanTDesigns »

bruce m wrote:dan,
point no 3 about lube groove location is not clear to me. could you elaborate on that please?
keep safe,
bruce.
Bruce,

Putting lube-grooves in long bore-riding sections reduces the risk of leading.
All the best...DanT..."The nation which indulges towards another a habitual hatred or a habitual fondness is in some degree a slave.” - George Washington’s 1796 Farewell Address
bruce m
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Re: Random Lube & Fouling Ruminations

Post by bruce m »

thanks dan.
that makes a lot of sense.
just the place to put a whole lot of low drag micro mini grooves.
keep safe,
bruce.
ventum est amicus meus
DanTDesigns
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Re: Random Lube & Fouling Ruminations

Post by DanTDesigns »

Bruce,

During the first half of the last decade, I performed a number of tests to determine how to reduce the drag induced by lube-grooves. A number of moulds were sacrificed during the testing. The first bullet was designed with what I call "standard" gg's. A few hundred bullets were cast and a match-grade load developed. Then, the mould was sent to a machinist friend to have the gg's removed. Finally, ammo was loaded with all components the same except for the bullets. Half the ammo was loaded with the gg version and half with the gg'less version. The ammo was shot from the 1,000-yd line to determine elevation difference. The difference was attributed fully to the gg's. With the standard gg's the difference in elevation was about 12 MOA. Several more moulds got the same treatment, but they had different gg designs. As the testing progressed, the difference between the gg version of the bullet and its gg'less version decreased. That meant that progress was being made towards reducing the negative effects of gg's on a bullet's BC. That is, drag was reduced.

During the first phase of gg-design testing, the NASA Bullet emerged as the drag-reduction winner. The difference between the single, long grease groove (0.250" x 0.020") and the version with the gg removed had been reduced down the just 4 MOA of elevation difference. I used stainless steel barrels through all of the testing. The NASA Bullet because quite popular for a while. But, some shooters were having leading problems that perplexed me. Klaus Schattleitner was shooting his NASA Bullet very successfully, but he was getting leading and therefore needed to delead his barrel regularly. It was conversations with Klaus that lead me to think that chromoly barrels were prone to leading more than stainless steel barrels. And, it got me thinking about how to reduce the leading problem, when using chromoly barrels, by adding gg's to the bore-riding section. That thinking was the genesis of the Money Bullet. The Money Bullet has the same gg-induced drag as the NASA Bullet, but with substantially reduced leading problems.

A few years later work commenced on MicroMiniGrooves that do not increase drag in an amount that I was able to measure. From the 1,000-yd line, MMG and grooveless bullets shot into the same group. By putting them on long bore-riding sections, no drag is added, the long bore-riding section improves bullet-to-bore alignment and the risk of leading is reduced. What's not to like:-))) However, MMG-only bullets should only be used in high-quality stainless steel barrels, never in chromoly barrels.
All the best...DanT..."The nation which indulges towards another a habitual hatred or a habitual fondness is in some degree a slave.” - George Washington’s 1796 Farewell Address
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deerhuntsheatmeup
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Re: Random Lube & Fouling Ruminations

Post by deerhuntsheatmeup »

I think here is a good place for me to inject that my "clean" bullet, or mistake bullet as some call it, has 5 mini grooves, and that design has served me well with the top groove right in the middle of the bore riding section. Very little leading in a Badger barrel, and very good accuracy out to 600.

Best, DB

PS Dan sent me the drawing to send to P Jones for my .40 cal Money bullet. However Paul chose to send me something else. Boy am I glad he did!
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mtnfisher12
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Re: Random Lube & Fouling Ruminations

Post by mtnfisher12 »

deerhuntsheatmeup wrote:I think here is a good place for me to inject that my "clean" bullet, or mistake bullet as some call it, has 5 mini grooves, and that design has served me well with the top groove right in the middle of the bore riding section. Very little leading in a Badger barrel, and very good accuracy out to 600.

Best, DB!
Do you have a picture of this bullet?

Thanks
SchuetzenDave
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Re: Random Lube & Fouling Ruminations

Post by SchuetzenDave »

Dan:

I appreciate your work do reduce wind drag by reducing interference from grease grooves.
Yes this will improve the BC and flatten the bullet.
While this is more important for very long range shooting or hunting; it does not seem to be as much of a factor for 200 yard Schuetzen or 550 yard BP Silhouette.

For precision target shooting Schuetzen shooters have found fantastic accuracy from high arcing bullets.
And at a fixed target distance it does not make any difference if I have to set my sights higher to hit the target.

Of course the risk of reaching a long distance target or chance of too much drop when hunting would be exceptions where I would prefer a bullet with improved BC.

But most of us single shot shooters prefer the classic looks of a rust or hot blued chrome moly octagon barrel.

We do not wish to alter our traditional rifles with a stainless steel barrel.

I did have one exception though.
My Money bullet would go to sleep before hiitng the Rams at 550 yards whereas my same weight Paul Jones Creedmore would not do that.
It took 3 grains more FFFg to stabilize my Money bullet.
Maybe it would have performed better with reduced grease grooves; but there is no way I am going to put a stainless barrel on my CPA, Rolling Block, 1874 Sharps or 1885 High Wall.

Dave
DanTDesigns
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Re: Random Lube & Fouling Ruminations

Post by DanTDesigns »

SchuetzenDave wrote:Dan:

I appreciate your work do reduce wind drag by reducing interference from grease grooves.
Yes this will improve the BC and flatten the bullet. While this is more important for very long range shooting or hunting; it does not seem to be as much of a factor for 200 yard Schuetzen or 550 yard BP Silhouette.

Dave, at the turkey line, a high BC bullet certainly is an advantage when the winds are reeking havoc on the bullet's trajectory. And, I would argue that even at 200 yards a high BC bullet, as long as it is accurate, will be an advantage. We all make wind-call errors; and, the less the bullet is moved about, the less effect our errors will have in the long run.

For precision target shooting Schuetzen shooters have found fantastic accuracy from high arcing bullets.
And at a fixed target distance it does not make any difference if I have to set my sights higher to hit the target.

A high-arcing bullet is a low BC bullet. Why is that an advantage? I can't wrap my head around that. A flat trajectory is a better trajectory, especially when shooting at extended distances. Wind speed typically increases with height and wind direction can change with height also. Wind sheer has bedeviled many a marksman, especially at Raton's Creedmoor range.

Of course the risk of reaching a long distance target or chance of too much drop when hunting would be exceptions where I would prefer a bullet with improved BC.

But most of us single shot shooters prefer the classic looks of a rust or hot blued chrome moly octagon barrel.

Stainless steel can be "blued" to look like a fine rust bluing. There are a number of top shooters out there that play in the various BPCR and Schutzen games that have stainless barrels that are "blued." They prefer to not tell anybody due to the fact that they see it as an advantage and don't want others to get the same advantage. I'm the kinda guy that is happy to share all I think I know about things. And, I'm just a dump engineer that chooses function over form. Don't get me wrong, I think the classic look is great and has great appeal, visually, to me, just like most of the guys/gals that play these games.


We do not wish to alter our traditional rifles with a stainless steel barrel.

I did have one exception though. My Money bullet would go to sleep before hiitng the Rams at 550 yards whereas my same weight Paul Jones Creedmore would not do that.

It sounds like your PJ Creedmoor bullet is unstable. Let me share what I learned whilst shooting with a friend down at Pala, CA about 14 years ago. Manny and I had shot together for years in the HP & SB silhouette games. Manny is an excellent shot and meticulous reloader. I suckered him into joining the BPCR games by loading my rifle for him and shooting together at a 3-day match. He purchased two top-quality Shilohs, one in 45-70 and one in 45-90. When he finally got his 45-70, we shot together at Pala during a 3-day, silhouette match. Friday was the first day of match shooting. We started on chickens. Manny got 5, IIRC, he cleaned the pigs, had some highs & lows at turkeys, don't remember the score. He sucked at rams; over the back, under the belly and then he completely missed. I think he only got 2 or 3. Manny's an excellent marksman, so I knew it was his load. When I asked, he told me he was shooting a 30-1, PJ Creedmoor under 62 grains of Swiss 1.5. I told him to load for Saturday with 68 grains. He lives about 70 miles south of the range so he was going home after the match. The next day, with the 68-grain ammo, he knocked down a lot of turkeys and rams. Oh, his rifle has an 18-twist barrel.

It took 3 grains more FFFg to stabilize my Money bullet.
Maybe it would have performed better with reduced grease grooves; but there is no way I am going to put a stainless barrel on my CPA, Rolling Block, 1874 Sharps or 1885 High Wall.

Dave
All the best...DanT..."The nation which indulges towards another a habitual hatred or a habitual fondness is in some degree a slave.” - George Washington’s 1796 Farewell Address
SchuetzenDave
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Re: Random Lube & Fouling Ruminations

Post by SchuetzenDave »

at the turkey line, a high BC bullet certainly is an advantage when the winds are reeking havoc
So what effects the wind drift the most. The BC or the speed of the bullet?
A better BC bullet flies flatter and faster.

However the increase in velocity from 1,000 fps to 1,700 fps increases the wind drift of a bullet.

That is why we use high arcing and slow moving cast bullets to obtain less wind drift for target shooting.

From Mike Ventrino and Steve Garbe Reloading Guide:

" To the target shooter, however, excess velocity is an enemy. As can be seen from charts found at the end of this book, wind drift increases as the bullet's speed increases until a certain point is reached. This phenomenon is caused by winds playing on the shock wave which builds in front of a bullet as it passes through the air. Such increases in wind drift continue until velocities pass 1,700 fps and then they decrease."

Dan: Who does the bluing of stainless barrels?
J.Murphy
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Re: Random Lube & Fouling Ruminations

Post by J.Murphy »

SchuetzenDave,
When shooting turkeys the wind that kills you is the wind you can't see, tiny gusts from whatever direction that push your bullet off target. It seems to me that a bullet that was the least sensitive to drift and was still accurate would beat the gusts that are there, but can't be seen. I ran the wind drift numbers for a 10mph crosswind for a typical BPCR bullet and found that 900 fps produced the least amount of drift. 900 fps is below what anyone shoots, but the question comes up as to just how slow can you go and still maintain a stable flight to the rams?
SchuetzenDave
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Re: Random Lube & Fouling Ruminations

Post by SchuetzenDave »

Steve Garbe has indicated about 1200 fps and to not exceed 1300 fps.

pg. 36 of the Reloading Primer:

"...the authors feel that about 1300 fps should be the maximum muzzle velocity for anyone trying to develop accurate mid-range (silhouette) ammunition."
DanTDesigns
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Re: Random Lube & Fouling Ruminations

Post by DanTDesigns »

J.Murphy wrote:....I ran the wind drift numbers for a 10mph crosswind for a typical BPCR bullet and found that 900 fps produced the least amount of drift. 900 fps is below what anyone shoots, but the question comes up as to just how slow can you go and still maintain a stable flight to the rams?
Jim,

Probably almost all of the exterior ballistics software out there is derivative of the late Dr. Robert McCoy's FORTRAN code, developed at the US Army's Aberdeen Proving Grounds. He said his equations were not accurate for subsonic bullet flight. A number of top marksmen have tried to shoot slow because their software predicted that a bullet's wind deflection will be minimized over the distance shot. That did not work for any of them. The trouble with shooting slow is that headwind an tailwind components will eat your score alive. Even the ODG's recommended shooting as high an MV as one could tolerate in long-range matches. Also, for a given velocity extreme spread, the lower the average velocity the greater the random vertical stringing.
All the best...DanT..."The nation which indulges towards another a habitual hatred or a habitual fondness is in some degree a slave.” - George Washington’s 1796 Farewell Address
DanTDesigns
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Re: Random Lube & Fouling Ruminations

Post by DanTDesigns »

SchuetzenDave wrote:...So what effects the wind drift the most. The BC or the speed of the bullet? A better BC bullet flies flatter and faster.

BC changes constantly as the bullet leaves the muzzle and starts to slow. And, if the bullet is not optimally stable, the actual in-flight BC can be considerably lower than the theoretical BC. That is why marginally stable bullets get pushed about by the wind so much. Since the in-flight BC is a function of the bullet's design, speed and stability, it's a combination of those three that predict how much the bullet will be deflected by the wind.

However the increase in velocity from 1,000 fps to 1,700 fps increases the wind drift of a bullet.

That is why we use high arcing and slow moving cast bullets to obtain less wind drift for target shooting.

I was under the impression that most Schutzen shooters were launching their bullets above 1,400 fps when using smokeless.

From Mike Ventrino and Steve Garbe Reloading Guide:

" To the target shooter, however, excess velocity is an enemy. As can be seen from charts found at the end of this book, wind drift increases as the bullet's speed increases until a certain point is reached. This phenomenon is caused by winds playing on the shock wave which builds in front of a bullet as it passes through the air. Such increases in wind drift continue until velocities pass 1,700 fps and then they decrease."

I beg to differ with the boys, certainly when it comes to long-range shooting. However, I will say that excess recoil is an enemy.

Dan: Who does the bluing of stainless barrels?

The Trinidad gunsmithing school and The Blues Brothers from Prescott, AZ "blue" SS barrels. There might be some others as I've not looked into SS bluing in a while.
All the best...DanT..."The nation which indulges towards another a habitual hatred or a habitual fondness is in some degree a slave.” - George Washington’s 1796 Farewell Address
gunlaker
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Re: Random Lube & Fouling Ruminations

Post by gunlaker »

To me the question of highly aerodynamic vs. more traditional style bullets only matters when working with specifics. For instance if you have two bullets of identical accuracy you'd be dumb not to choose the one that reduces errors due to misreading the wind.

I think it becomes more interesting if you make a comparison between bullets like the Saeco 740 and something like the Kidwell Money bullet. This is of course directly interesting to me as I shoot both of them :-). At distances of 200m/yards, the Saeco bullet is a little more accurate in my rifle. But the money bullet ought to make up for this as the distances increase if there is any appreciable twitchy wind.

Chris.
DanTDesigns
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Re: Random Lube & Fouling Ruminations

Post by DanTDesigns »

gunlaker wrote:To me the question of highly aerodynamic vs. more traditional style bullets only matters when working with specifics. For instance if you have two bullets of identical accuracy you'd be dumb not to choose the one that reduces errors due to misreading the wind.

I think it becomes more interesting if you make a comparison between bullets like the Saeco 740 and something like the Kidwell Money bullet. This is of course directly interesting to me as I shoot both of them :-). At distances of 200m/yards, the Saeco bullet is a little more accurate in my rifle. But the money bullet ought to make up for this as the distances increase if there is any appreciable twitchy wind.

Chris.
Chris,

Estimated BC of the SAECO 740 is 0.406. The estimated BC of the Kidwell Money Bullet is 0.475. The stability of both bullets out of a 16-twist barrel is fine out to 600 yards. It is only 2.4.
All the best...DanT..."The nation which indulges towards another a habitual hatred or a habitual fondness is in some degree a slave.” - George Washington’s 1796 Farewell Address
bruce m
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Re: Random Lube & Fouling Ruminations

Post by bruce m »

brian litz, the ballistician for berger bullets strongly makes the point that it is virtually impossible to over stabilize a bullet from a shoulder fired rifle.
for the highest b.c. in flight the bullets axis must at all times be as near as possible to a tangent of the trajectory curve.
it will never quite achieve this due to the yaw of repose, in which the nose will be a little to the right and a little high in a right hand twist barrel.
the more consistent this is in flight, the higher the average b.c during flight.
a bullet with spin slightly greater than required is far better in this respect than one with slightly less.
when slightly less spin than required allows the bullet to yaw a little more, and this is often temporary, its frontal area increases dramatically, increasing drag at a similar level, thus reducing b.c.
this induces vert bigtime.
the bullet is also self steering to some degree, so a little wobble of the axis can also steer it in another random direction as well.
brian is a great believer that a little more than optimum stabilization is a good thing.
of course modern ammo is quite stable at a stability factor of 1.5, while ours seem to need well over 2.0 to perform at 1000 yds, particularly with blunter noses.
a bullet travelling In a 3.00 o clock wind will have a different yaw of repose than one travelling in a 9.00 o clock wind.
generally this is not an issue if the wind does not change much, but during the 3 seconds of flight to 1000 yds there can be several conditions during flight.
if you add in a windshear on the way to the target, the bullet can be in a seriously confused state trying to change its yaw of repose for a stable flight.
in order to minimize these issues, plenty of spin offers the best accuracy.
keep safe,
bruce.
ventum est amicus meus
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