Does nose shape matter at subsonnic velocities?
About 20 years ago I was shooting with one of my shooting Idols, Dave Gullo of Buffalo Arms in Sand Point Idaho. I had read about Dave Gullo, bought a lot of stuff on his online store site for BPCR supplies and equipment, I had run into him at a cannon shoot aoutside of Farragut Idaho and he and his shooting partner had invited me to his house to go shooting.
I had just gotten my Sharps Borschardt back from Doug Turnbull, had it with me and was excited to show Dave Gullo my prized rifle.
the Borschardt and some 457658 spitzers
At the range that day I pulled out my ammo, which was loaded with the Lyman 457658 which was a 485 grain spritzer. Gullo looked at the pointed 45/70 cartirdges, shrugged his shoulders and said, “you know those spritzers will not fly any better than SWC or round noses”
I was shocked, Gullo was like the BPCR god at the time, he would a year or two later win the Creedmoor worlds championship in South Africa that was restarted after close to a century of absence.
Gullo went on with his sacriledge, “Have you heard of Franklin Mann and his book Bullets Flight From Powder to Target?” I nodded that I had heard about it. Gullo then said, Mann proved that nose profile has no bearing on the flight of bullets that are subsonic.
I have never read that book, “Bullets Flight From Powder to Target”, cover to cover. I have found it online and browsed thru it looking for that information regarding nose profile affecting trajectory in sub sonic velocities, but browsing thru a book on line is not a good way to get every bit of information out of it.
Well I knew it made a big difference in super sonic bullets, but I had not heard of it in sub sonic, I eventually stopped using the 457658 bullet, because it did not perform as well as other bullets I cast for, but I always wanted to see it on target to prove it to myself.
I have brought this subject up before, as when Mr Hollowpoint came out with his spitzers that were to be long distance bullets.
Handloads.com shows a large difference between SWC and spitzers trajectories, the spitzer with a 81.4 grain bullet weight drops a full 12 inches less than a 81.5 grain SWC with the same velocity and same 100 yard zero, the Handloads.com ballistic computer is also for super sonnic loads. When I bought the spitzer mold off EBAY I had checked the trajectory and really felt it would extend the range of my Haley, but Gullo’s words still echoed in my mind.
Well I tested it today to see for myself.
I shot the NOE SWC bullet at 81.4 grains against the 84 grain 257388 Ideal/Lyman bullet at 260 yards.
Same sight setting, same air pressure, close to the same velocity, the difference that 2.5 grains would make, same alloy and lube, one bullet was 2.5 grain heavier than the other.
And they shot groups in the same postiion at the target dots I was shooting at, the 84 spitzers did not fly flatter than the 81.5 SWC even though Handloads.com said they should shoot 12 inches higher.
I need to do more work on wind drift, the spitzers did drift farther than the SWC bullets.
So your turn, tell me I made a mistake, that Gullo was wrong that this just can’t be.
All Replies
Leadbetter,
It probably is about that long slender pointed nose sure enough, that and wind.
I read Elmer Keith as a youngster and got my first Mdl 29 at 22 years of age. At my first duty station we had an old boiler that I could get 440 yards from and I used to launch those 429421’s at it by aiming at a sage brush on a ridge behind it.
I was hooked, air guns shooting at long range with cast bullets are in the same league in a lot of ways. Shooting 260 yards here with the Ranger 45 and 400+ grain bullets brings back a lot of those pleasant memoires.
RC
My bad rc, I did not clarify I do shoot handguns at long range 250-300 yards with cast slugs. Genarally In handguns at long range the swc slugs do out preform wfn lbt at all velocites. Never tried a cast spritzer in one. Know a bprc shooter that told me about a spritzer design that had a boatail said it was one of the worst designs he’d seen.
I gave a try to a 257312 HP and dont like it a lot,but still searching for a 257283 .
I agree about spitzers especially on windy conditions….Airguns are a different league according bullet design…i found that round nose and SWC performs the best due subsonic.
Another factor i usually pay attention is the GC instead PB…GC helps to leave less lead flashing on the tail and works as a boatail too.
Leadbetter,
Butcher is correct that I am looking at long range here, and long range for an air gun in this context being 250 yards and beyond.
Yes nose shape does matter, and on a subsonic projectile I am finding that spitzer shaped is not good but not for the reasons I originally thought.
To recap look at the M80 military round. It is generally accepted that at 660 yards the accuracy of it’s 147 grain bullet degrades as it goes subsonic and is subjected to transonic waves that disrupt it’s flight. That is why long range shooters using a 308 opt for heavier bullets to retain that velocity above transonic for a longer distance.
Then look at BPCR target shooters who never go beyond supersonic and choose to stay in the 1000 to 1100 FPS range. 22 target shooters for the same reason choose the sub sonic round.
The BPCR shooters and 22 target shooters are choosing not to subject their projectiles to that subsonic buffeting, but as you pointed out centerfire pistol shooters get pretty good accuracy with their 44 mags at 1300 FPS, but they are for the most part shooting short range and not looking for sub MOA at 250 yards and beyond.
Now to the spitzer and what is wrong with it. The nose shape that at supersonic velocities serves so well, at subsonic velocities is a detriment, it allows the wind to catch its long slender nose, and that causes instability, that instability causes more surface area to be exposed, which in turn lowers the BC which in turn causes more drop than what a one size fits all ballistic table, designed primarily for the use of spritzers in supersonic velocity, would reflect.
In application, when I shoot in the absence of wind at subsonic velocity, I get the improved trajectory the chart would suggest that a spitzer would have over a SWC bullet, if I shoot in the wind, the spitzer exhibits more drop at 260 yards SWC at 260 yards.
Again at 50 yards this would probably not be noticeable with a 44 mag and 250 grain bullets.
Regards,
Roachcreek
I’ve shot some real nice 50 yard groups from my 909 using WFN slugs……definitely going under 800fps. 50 yards seems to be “old news” these days, though LOL.
I think RC is mainly looking at trajectory, though.
Rc,
Haven’t owned any big bore air rifles yet but I’m going to make a observation and ask a question. LBT style slugs in handguns shoot great when pushed @1250+ fps by x magnum revolver but fired @800 fps from a .45 colt revolver you’ll get shotgun patterns. When using Keith styled SWC bullets velocity from 700-1300 gives great accuracy. So nose shape did play a role as far as pb handguns go IMO. That’s been the case with lots of handguns I handled. My question is does the 1200+fps rule for handguns firing LBT slugs apply to airgun? That’s a great looking rig you got there!
KQ,
I am blessed to have a range where I can sit on the deck and shoot to 260 yards, the draw back here is being a cut in a open forest on the east side of the coast range the wind swirls on my range.
There are 4 wind flags, and most of the time at least two are pointing in different or opposite directions and at times all four are pointing to different directions.
Seems I have always been plagued with a good way to read the wind, at my mountain place and the two ranges I competed at, the bullet flight was 150 feet or more above the canyon floor to the canyon wall where the targets were, and not having 150 foot high poles to put wind flags on, we had to shoot for effect and then do corrections and a follow up shot.
Changing postions will not work here, but I can either turn my barrel around, or shoot thru a mirror to get the twist going the other way. 😛 .
What I am after is to try and get the furtherest zero on my scope that I can using the 107 MOA of adjustments and the 24 MOA reticle, I want to shoot at 6 and 700 yard distances, which is why I purchased that spitzer mold.
RC
Charlie…
if Jim Allison was healthy and still stayed in business,i would give a try to one of these at .257 cal.
Right now i think about the Saeco mold.
I know it looks a little bit weird as a design but do you remember when i was talking about collected ring cavities close to the bullet base?
Also i ll keep wait patiently Cendric’s result about those soup cans bullets ….looks very interesting to me and i think he is on the right way…..i have a good feeling about it and doctor Miller agree too…..but still don’t know what gun he is going to try.That one below is with his Talondor and off course it belongs to theory for the time being.
The only thing i m worrying about is that for a range up to 220-250yards always needed a 2.0sg for a great accuracy.
Lets hope οnce again,practice proves the inadequacies of ballistic calculators
So….Wind weakness or wind direction?…what makes the diference..??? 🙄
Next time on a windy day try to change position with the target or use a barrel with anticlockwise twist.. 😀 …Im just curious what the result will be.
LOL!!!…Why didn’t you mentioned about the windy condition from the begining?….this explains what happened.
This is the most negative factor on bullets balistic and called MAGNUS EFFECT. http://upload.wikimedia.org/wikipedia/commons/e/ea/Magnus-force-bullet.png
Thats exactly spitzers fear every time the wind being stronger….and thats the reason i put stainless ball bearing in bullet mold(flat nose) before pouring the lead.
The smoother the surface is,the better the BC will be due to the minimal friction between the air and the bullets nose surface.
I just remind you what i was saying to my previous post…..Spitzer(means sharp in german)are very sensitive and need a particular dose of twist ratio(not faster or slower).
If you make them spin more than normal,then the Magnus effect increased due the widest angle of nose instead other bullet categories,and are affected even more after airflow raise on a strongest wind .
Just when I thought I had this figured out.
The wind died down around 6:00PM, so I hiked down the hill repainted the targets, cleaned the 1-10 twist barrel and decided to shoot every bullet I had doing 3 shot groups to just test drop using:
257420 HP
Ideal 84 grain spritzer
NOE 81.5 grain SWC
NOE 100 grain SWC
Hoch 109 Round nose
Again no wind, 1-10 twist, zeroed at 260 yards with the NOE 81.5 grain SWC.
I held in the center of the plate and shot first the 71 grain 257420 HP, they hit 12 inches high, chronied 1120 FPS, then the 84 grain spitzers, which intermingled with the 257420’s 12 inches above the plate.
Then the NOE 81.5 grain bullets which hit on the plate, then the NOE and Hoch 101 and 109 bullets which hit below the plate near the 6 MOA mark.
The NOE 81.5 and the Ideal spritzer were still chronying at 1080FPS in the 1-10 barrel.
The Hoch and the NOE 100 grain bullets now were intermingled together, so no wind was a factor in making the Hoch shoot flatter.
Evidently the faster twist and combination of no wind stabilizes the Ideal bullet better, giving less wobble in the wind and giving the spritzer a higher BC.
They all shot very well. The NOE 81.5 grain bullet seems to be the most consistent performer in this rifle, whether in the wind or with different twist barrels.
All good ideas, but I am not talking so much about accuracy here as I am talking about the error of Handloads.com ballistic calculator saying the spitzer would shoot flatter due to a pointed nose and resultant higher BC, and which in this case shows no advantage over the SWC at subsonic velocities.
In super sonic velocities the spitzer is well established to have a superior trajectory than a blunt nosed projectile given the same weight and velocity, we all know that, but in sub sonic travel, I do not think it matters.
And I don’t think the people who write the ballistic calculators realize this and use a super sonic criteria fits all.
Harry from OZ brought up a good point in that a sub sonic spritzer does not do well in the wind, which would destabilize it and thus expose more surface area and lower the BC. I think being sub sonic they simply have or need a different BC formula.
I repeated the test today with a 20 shot group, 10 of each, and a 10 shot group 5 of each. I had the usual swirling wind which blows to all four corners of the compass, so I had a couple low shots an a couple high shots, but nothing to indicate that the spritzer should shoot 12 inches flatter with the same velocity 1080 or the same sight setting. The velocities overlapped each other and the groups overlapped each other.
And I have done exhaustive tests with different fill pressures and the result that the fill pressure influences velocity differences whcih influence accuracy on the NOE 81.5 grain bullet, the Hoch and the Lyman 257420, not so much on the Spitzer as of yet.
Harry also said that bearing surfaces on the bullet could change BC, and the spitzer does have more bearing surface, but over the chrony, which decided to work today, the velocity was the same for both bullets.
It should come as no surprise that the Ballistic computers get it wrong. Chairgun, if you plug in a 71 grain 257 projectile will not give the correct BC and it gives very inaccurate ballistic trajectory information until you enter the correct BC yourself, and even then is is inacurate. Handloads.com if you plug in a 25 grain 257 bullet is not even close to the pellet trajectory, and it is because these are all sizes fit all for the job they are intended to do. And even the BC Handloads.com gives for the 257420 has been proven wrong by Tofasfou with two chronies working at different distances by yet another ballistic calculator.
On SWC at subsonic velocites Handloads.com will give me close long range corrections to 260 yards if I get a 40 yard zero, and then enter the velocity and the range I want to shoot, to with in a foot or so usually at 260 yards, and with sub sonic SWC a foot is pretty close, but then it is that same foot, 12 inches that they got wrong on spritzer vrs SWC.
Here is where it gets further muddled and in fact KQ clears up somewhat. The Hoch 109 round nose and the NOE 101 grain SWC, which is actually closer to a spitzer than a SWC. The NOE shoots much flatteer than the Hoch bullet in the 1-10 by simply interchanging bullets with the same fill and sight setting like I did with the two 80 grain bullets in the 1-14. Now in the 1-14, the Hoch bullet shoots much flatter than the NOE 101, but that is because the NOE bullet seems to never ever hit the target, and I mean never, where it goes is anybody’s guess, but it is obviously key holing on its way to parts unknown.
Why I say KQ explains this is look at the picture, the NOE 101 has the bands in the middle of the projectile, it is closer to a spitzer than a SWC in shape, putting its bands and thus its weight in the center, the gas check shank may even act as a boat tail, which KQ illustrates as a recipe to success The Hoch and the NOE are almost identical in length, but the 1-14 only shoots the Hoch well and the NOE not at all, at the same time the NOE vastly out performs the Hoch in the 1-10.
We all have bits and pieces of the puzzle here, and international discussions like this one gives us ways to help solve these kinds of mysteries, which in the end proves the inadequacies of ballistic calculators, for it is the inaccuracy of ballistic calculators and their one size fits all aproach that created this mystery for us, it us, with our ideas, our experiences and gained knowledge, proven by range and trigger time that will sovle this, not a ballistic program trying to solve all projectile problems.
Franklin Mann did not have a ballistic calculator, he had formulas and range time, although I have not found his exact quote yet on this subject, it seems he had the answer over 100 years ago to this problem.
I would say yes and i have to admit, i’m NOT putting too much thought into this answer but,
It reminds me of simple things that we do all the time but we never think about. One is holding your hand out the window while driving and you turn it “FLAT” into the wind. Then you turn it on “KNIFE EDGE” and you’ve got very little resistance. And we ARE going sub sonic……lol! So a wide meplat vs a spitzer shape has to have some differences in resistance during flight at subsonic. Others are like a Corvette vs a Semi Truck driving down the freeway. Gotta be a shit load of wind resistance on the TRUCK vs the Corvette.
But of course, i’ll probably be proven horribly wrong……….. 😆
RC…
For bests results on a spitzer you need one which have all the ring cavities collected on the rear in order the removed material get in balance to the material is missing from the nose.
…or a deep boatail design in order transfering the center of gravity and drag slightly in front of the middle of bullets body and keep the tail stable due the vacuum it creates while is on flight.
…If you can made this,dont worry much about supersonic…off course it s an important factor on airguns but you can live with this if you do right other very important things.
Personally i get a 1.5″ group on 250m regardless if i shoot my 105gr bullet at 1113fps which is supersonic at my area…..and guess…it’s a UNSIZING FLAT NOSE ONE!!!!!….and you know about this.
I agree….great topic here.
Well as KQ mentioned above i’d say yes given it’s relationship to the rest of the projectile and it’s subsonic velocity. But it’s a complex deal with a bunch variables.
For instance the Surefire slugs have a blunt nose and work well in 25 caliber but not 22 caliber…
Wad cutter ‘diablo’ pellets have blunt noses and can be very accurate at low velocities, not so much at higher subsonic velocities.
Some round nose ‘diablo’ pellets shoot well when others don’t.
Factor of material, bore, twist rate, bore length, velocity, nose shape, length, tail shape, ambient conditions.
I’m always a bit skeptical of accuracy/performance testing where velocity is matched with different projectiles. For me finding THE best accuracy for each projectile should be the baseline for a comparison between two projectiles.
In a powder burner 0.2 grains of powder makes a difference. Why wouldn’t a few grains forward of the cg in a subsonic projectile not make a difference too?
For discovering the best performance for a given projectile I would try a spread of velocities to at least confirm or eliminate the possibility that a different velocity may produce a better or worse group. Even different twists may be needed for slightly different projectiles. To say one works better in a specific situation is to quantify or bracket the idea of performance, but to say because one projectile works better than another in a specific barrel doesn’t mean if things were changed the other projectile may perform as it’s equal or better.
I guess what I am saying is if you state ‘x’ bullet is better than ‘y’ bullet it needs to be bracketed by “in a twist rate of ‘r’ with a velocity of ‘v’, from a barrel length of ‘l’…” Because these are all factors that effect the projectiles performance. People are finding that the same pellet can have different bc’s out of different length barrels, not to mention different groove numbers, twist rates, etc.
In terms of wind drift different nose shapes will be effected in different ways. A really pointy nose will have less effect on the nose of the projectile in a cross wind. A blunter nose would have more imparted effect from a cross wind on the forward portion of the bullet. The amount of effect in front of or behind the spinning cg of the projectile can impart different upsetting factors that may effect accuracy to a lesser or greater effect. You could have wind drift and/or side wind created instability. Some projectiles may string out horizontally from cross wind influence and some could start to spread vertically depending on shape.
Great topic RC! Get’s the brain juices flowing!!!!!
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It has been proven over and over again that at subsonic velocities, tail drag is a greater influence than nose drag. The sharp point works well at supersonic speeds but does not help at subsonic where a decent ogive is best. Just look at the old A-6, what an ugly aircraft (if you’re into pointy fighters) but extremely aero-efficient.
The money spent on ballistics calculations has for years been spent on high speed projectiles. Nobody with cash (i.e. Army) cares about pistol rounds, much less subsonic airguns. That’s why all our calculators are best guesses and we often find the same epiphanies over time.
One other thing that complicates the issue is that most of us don’t have interchangeable barrels with ledes cut for a particular bullet. I have found that even a pointy slug that works well from one barrel, won’t work from another (same twist) barrel at the same velocity due to not seating as well. That doesn’t change the point about aero efficiency but it does make it harder to prove anything about anything!