Old-Win

I'm not a Shuetzen shooter either and like you, I respect the accuracy that they are able to achieve.  As to the reason for shallow grooves on Shuetzen bullets, I'd like to propose the following reason as a possible answer.

Back at the turn of the 20th century, Ideal offered their "Perfection Mould" to shooters which allowed the shooter to cast various weights of bullets having different lengths.  Depending upon the caliber, the number of different bullets that could be cast with the mould ranged between four and seven.  Some of those heaviest bullets were quite long.  This was great for a Shuetzen shooter because he could try different weights and select the bullet that performed best in his rifle.

I've got to believe that cutting all those grooves in a long bullet was hard on the tool steel cherie that they used to cut the iron mould.  I suspect that to reduce springing of the cutter and to increase tool life, they made the grooves shallow as a manufacturing expediency.  Since the bullets provided good accuracy, other mould makers imitated their pattern of shallow grooves.

Does that seem to be a logical explanation?

feather

Pete,

I agree with you with respect to the more narrow and shallower depth of grease grooves for use with smokeless powders. Actual testing has shown that a 32 caliber bullet having only 2 narrow and shallow grease grooves (.040 wide x .016 deep round bottom) carries adequate lube when fired at 1550fs. Although we make moulds with 3, 4, 5 and 6 grooves, many shooters are using our 3 groove bullets with no reported leading problems. Comparing two identical bullets cut with the same cherrie one with 3 grooves, one with 5 grooves, the 3 groove bullet will have slightly higher retained velocity at the target than the 5 groove, this is due mostly to the increased weight of the 3 groove. Again, this applies to smokeless powders only.

Exhaustive testing has proven that a 16 inch twist 32 caliber barrel can stabilize bullets upto 1.165" long at 1475fs. As you know increasing the weight of a bullet will improve its ability to retain its downrange velocity. However I must point out that the larger metplat will most often offset any increase in weight due to increased aerodynamic drag. For instance, tests comparing a 191 grain 6r ogive spitzer vs a 210 grain 5r ogive spitzer (same length) have shown the 191 grain spitzer bullet has the better retained velocity and faster time of flight. The differences change rapidly beyond 100yds. I have tested and profiled most of the 32 caliber bullets we offer instrumentally in 25yrd increments to 200yds. In my opinion nose form factor is more important than weight alone.

7~

Barry,

  I agree with your assessment about the number of lube grooves actually required with smokeless powder. In fact I said about the same thing in another thread.

  What would you say to the same reduction of lube when shooting BP if you wiped between shots? I think the same as with smokeless but haven't done any side by side comparisons to say. Just a gut feeling. So am open to other opinions.

  I think you could go down to even less than 3 lube grooves if you wanted. As I've mentioned a Lyman 311334 with two lube grooves and being driven at pretty close to 1500 fps hasn't shown any Leading. I have taken it up to 1785 fps with no Leading, but there's no accuracy. Alloy is 50/50 WW/Pb. The problem(?) with this bullet is that it's about 2/3rds bore riding, so I'm not sure if this amount of lube would prevent Leading if the bearing surface was longer. Your thoughts?

  So far what I've found is that different calibers and bullets require different amounts of lube. My main .32/40 bullet shooting smokeless, which is a Barnett copy, does best with all grooves full, and a Win. 185 gr. bullet shoots best with one less groove of lube.. The Lyman 457125 wants two grooves less and the 600 gr. bullet I use in my .50/90 needs them all full. The latter two are being shot with BP and the bore wiped out for each shot. What's your thinking on all this?

  I can see the increased meplat increasing drag and wouldn't recommend it as soemething to get. I was just using it as an example to show how bullet wgt. can be increased without increasing the length.

  I'm glad you mentioned the actual max. length that a 1-16" twist can handle. Didn't know that!

  Nose form factor....... Can you go into this in a little more detail? It seems to go against common sense that a 191 gr. bullet would have better retention of velocity... which should equate to a higher BC..... than the 210 grainer with only a 1 degree difference in the radius. It would seem that just the difference in wgt. would be enuf to offset that small a radius change. How big a difference are we talking here?

  Something I read recently says that at Schuetzen and BP velocities BC isn't affected all that greatly by nose shape. If BC isn't affected then I would think downrange ballistics wouldn't be affected greatly either. Playing with different BC's and a computer program I've found that it takes around 50 points difference in BC to see any realistic changes in trajectories, and remaining velocities. Confusing to say the least since everybody puts such great emphasis on it. But.....You've done some actual work on this, so would be interested in your thoughts?

  This is getting interesting! 

PETE

Barry,

  Excellent! Just what I was looking for from you. Someone who's done actual work. Computer programs are ok for a general overview but will never beat actual testing. In a lot of shooting cases close ain't good enuf.

  Looking at a chart of nose radius' (Coxe & Beugless) the difference between a 4r and 6r nose (closest my chart shows) is very small. In fact very hard to visually see the difference. This would lead you to believe that all else being equal..... as you point out your test setups were..... that the heavier bullet would be slightly better in all departments.

  Very interesting points you've made. Have you tried this with more radical differences in nose radius'? Say a 2r vs a 6r. If so, at what point will the results tip in favor of the heavier bullet?

  Then I get to wondering about a spitzer vs a flat nosed bullet. since a lot of people seem to think a nose pour bullet is better than a base pour, a true spitzer isn't possible. I wonder at what diameter the meplat would have to be before downrange results would be close enuf so that any differences wouldn't show up, just due to the "soup" of natural conditions acting on the bullet externally. Your thoughts?

  Changing Lead alloy affecting downrange efficiency...... Now this is a new one on me!

  Are you sure you don't mean a 1-20 bullet will weigh LESS than a 1-25 or 1-30? Tin being lighter than Lead any addition of Tin to an alloy should make it slightly lighter.

  In any event, do you have some velocity comparisons at the various ranges you test at to show this loss?

  Something that just popped into my head. I've read that some think a lube can be to slick. Have you done any  testing with different lubes to see if the various types cause differences in velocities?

PETE

Steve,

  I think it was mentioned that after the first shot, even if you wipe out, there will be some lube left on the barrel. If you shoot dirty, after the first shot, there would be plebty of lube and soft fouling to "grease" the way.

  Altho the following is also true of my .45/70 and .50/90 BP loads I'll use as an example the 417 gr. .40/65 bullet I'm working with now. Since I shoot almost every day during the Summer I just leave the bore wet with my cleaner and at the range just run a dry patch thru to get rid of the excess. Or, if I'm shooting the gun for the first time that year, I clean it, and then follow the same procedure at the range.

  With the above bullet the first shot will always be in the center of the group. Using a blow tube the successive shots will be around it. Now with that first shot there is no lube in the bore, yet the barrel doesn't Lead up. If it was Leading up then groups would get worse real fast.

  Now this isn't a rare occurence and part of balancing a BP load for me is to try and find a load that will do this. With BP it seems to work most of the time. With smokeless it doesn't. I wish I knew the why of that!

  The long way around is that personally I wouldn't worry about an unlubed nose being a detriment to accurate shooting. A bore slightly damp from your cleaner seems to be enuf lube for at least one shot.

  Now here's an idea I've read that some do. If this unlubed bore bothers you then some will run a patch with their lube on it back and forth several times down the barrel followed by a reasonably tight, dry patch to get rid of the excess. Seems to be a favorite trick of some of the top ML'ing shooters. They call it seasoning the bore.

  Take it for what it's worth as I've never tried it. If you do let us know how it works out.

PETE

Pete,

Yes I have done comparative ballistic tests with 2r ogive upto and including 8r ogive spitzers and comparisions of flat nose also. In each case the larger ogive radii bullets with metplats of .030/.050 dia. of similar weights have shown to have the better target velocities. The following is a partial list of tested bullets and their efficiency factors for 100 and 200 yds. Just as the BC is the same for each particular bullet at a given range the efficiency factor also remains esentially the same for a given range within the 1350fs to 1550fs velocity range we normally use for schuetzen shooting. Therefore, if you multiple your chronograph MV x the EF(efficiency factor) of a bullet that has been characterized the resulting down range velocity will be close to 1% of the actual downrange velocity. 

190grn Flatnose .115 metplat = .892@100yds .789@200yds
200grn Flatnose .115 metplat = .895@100yds .799@200yds
190grn Pope      .145 metplat = .882@100yds .773@200yds
190grn 6r Sp     .020 metplat = .905@100yds .804@200yds
190grn 3r Sp     .060 metplat = .881@100yds .769@200yds
200grn 8r Sp     .045 metplat = .912@100yds .823@200yds
210grn 5r Sp     .040 metplat = .906@100yds .808@200yds
216grn RdNose  .060 nose R   = .902@100yds .809@200yds

This comparision shows the effect of both nose form and weight on bullet efficiency or retained velocity. When conducting bullet tests I repeat previous tests again on different days, slight differences occur mostly as a result of barometric pressure more than other atmospheric conditions like temperature (65F-85F) or humidity.

With respect to what would be the best of both worlds, weight and nose form for a 16inch twist barrel, my current choice would be the 6r spitzer with length increased to 1.165. Further testing is still needed next season on some new designs that are a result of this past years work. I do beleive that the nose length can be too long resulting in unexplained flyers, this seems to be true of the 200grn 8r spitzer. This years test series consistated of over 5000 shots of 15 different bullets designs, pressure tests were also conducted on each bullet design/weight.

I suppose I could have worded the difference in alloy weight better, I meant to say that a bullet mould that casts a 200grn bullet with a 1 in 20 alloy will cast a bullet about 2grns heavier when a 1 in 25 alloy is used. The 1 in 25 alloy will have better retained velocity than the 1 in 20 alloy due to the 2 grains of weight.

Years ago I experimented with many different bullet lubes and can't say as if any were too slick. With smokeless powder powder fouling sometimes occurs and is mistaken for leading. This fouling occurs in the throat and occassionally about 14" from the throat where the peak pressure point occurs. I don't beleive bullet lube is as important for smokeless shooting as for BP.

Barry

Barry,

Ok! Good post. But, I need to get this efficiency factor straight in my head. Remember... I skipped school the day they had math.  In other words you're getting ahead of my understanding of your work and I sure do want to get a handle on it.

  Looking over your chart I'm trying to relate the efficiency to the numbers you give. I THINK the higher the number the more efficient. Right? If so, I get it, but if not I need some dumbing down about it.

  Atmospheric conditions....... Forrest Asmus and myself have been trying out the idea of using one "reading" of the conditions to see if we can't get a handle on retained velocity and it's effect on group size. Density Altitude is what we've been looking into. Rather than go over the whole thing we are trying to do, look up a past thread on this.

  Do you believe that Barometric pressure has more to with down range velocities than temp. and hunidity?

  We've all seen our rifles go "sour" in the middle of a match, for no reason we can relate to. I would think that barometric pressure would just be to slow acting to show these sudden changes. Using a Kestrel 4000 which will show you about any atmospheric condition you care to name, I'm beginning to believe temp. has the most effect on groups at least.

  Correct me if I'm wrong..... But isn't a lot of the barometric pressure you observe due in large part to temp. & humidity? If so then I would think that retained velocity would be more affected by these two factors. As the air warms in the morning the humidity will fall. As the humidity falls the air becomes more dense, and would retard a bullets flight more.

  I might be on the wrong track, but my observations so far this past Summer seem to show that about a 10 degree rise in temp. needs a corresponding decrease in powder charge in order to maintain velocity and accuracy. I'm talking smokeless here for those interested.... and not!

  So, I'd like to hear why you think Barometric Pressure is the more important factor to see if my thinking is correct or needs revision.

  I have read that the Creedmoor shooters kept a barometer, and humidicator in their loading tent. Altho not mentioned I would assume they also had a thermometer to.

  To slick bullet lubes..... I'm with you on this, but some seem to think if a lube is "to slick" the bullet can get ahead of the max. pressure wave when it's bumped by primer ignition. The thinking seems to be that you'll end up with the bullet traveling down the barrel with a Yo-Yo effect. Speeding up and slowing down as the pressure wave catches up and gives it a bump then slowing down as it gets ahead of the front. It's felt what's needed is the right lube consistency to act as a sort of drag so this doesn't happen. I'm not sure this would be applicable to BP as there is enuf drag induced by the fouling. More something that would affect smokeless loads.

  To prevent, or slow the primer bump it seems like a lot of BP shooters are going to the pistol primers.

  As an aside and FYI..... I've been looking down the muzzles of other competitors barrels.... unloaded of course  ..... and see what you mean. Also have used those observations to tell when I'm getting close to the optimum load. I wasn't to sure about that at first, but see your point now. Amazing the variations you'll see.

PETE