GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: skorec on December 07, 2019, 03:35:24 AM
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Description of FX slugs:
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The FX hybrid slugs benefit from the external dimensions of a high ballistic coefficient slug design, but have a completely hollow core and recessed base. Therefore making it light and easily shot accurately by most PCPs. With these FX hybrid slugs you can achieve velocities and trajectories much greater than any other slug or pellet. The FX hybrid slug will provide a flatter trajectory, less wind drift, retained energy at longer distances, and more accuracy at those distances than any pellet. The hollow core provides massive expansion, incredible for hunting.
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If the BC is so good why not produce the slugs from tin ?
Unfortunately If I change bullet density at Colbe from 11,4 to 7,6 the
BC has decrease two times ( from 0,04 to 0,02 at my dreamt-of caliber .14 )
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.14&length=.23&nose=.1&meplat=.04&drive_band=.14&base_diameter=.14&angle=0&boat_tail=0&secant_radius=&weight=5.3&density=11%2C4 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.14&length=.23&nose=.1&meplat=.04&drive_band=.14&base_diameter=.14&angle=0&boat_tail=0&secant_radius=&weight=5.3&density=11%2C4)
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.14&length=.23&nose=.1&meplat=.04&drive_band=.14&base_diameter=.14&angle=0&boat_tail=0&secant_radius=&weight=5.2&density=7%2C6 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.14&length=.23&nose=.1&meplat=.04&drive_band=.14&base_diameter=.14&angle=0&boat_tail=0&secant_radius=&weight=5.2&density=7%2C6)
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Well it found one answer to your question. Here's a few others.
Lead is cheaper, but more importantly much more malleable than tin, thus lending itself much more easily to being able to alter its shape slightly when being propelled down the bore. With the low pressures used by our air guns, this is necessary at the breech to form a gas seal, and at the muzzle to be able to be squeezed down when passing through the choke.
Lead is a lubricating metal, tin is not.
Another is that tin is much harder than lead. I strongly suspect that shooting pure tin ammo on a regular basis would rapidly wear out our barrels.
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Thanks, I am just trying to find out slugs for 11 FPE AGs and YES you have true for sure but :
1. Tin pellets are using - probably only at conservation areas
https://www.amazon.co.uk/RWS-HyperDome-Pellets-Airgun-Control/dp/B00ICLF2LG (https://www.amazon.co.uk/RWS-HyperDome-Pellets-Airgun-Control/dp/B00ICLF2LG)
2. Why hollow core lead FX hybrid slugs have so good BC=SD/FF=0,08 ?
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I hate to burst your bubble some, but the FX slugs weigh 22 grains. They are also a tight fit in the gun that I'm testing (a springer) them on. The gun normally shoots about 15-16FPE. I'm only seeing about 480 fps, which translates to about 12 FPE. I'll be testing expansion today, but I would suspect that you may need as much as 700-800 fps on target to get proper expansion.
As Mod90 correctly stated, tin is harder than lead. I doubt that I would even be able to chamber a tin equivalent of the FX slug.
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I did cast some .22 NOE slugs in tin, I used the flat nose pin, figured hardly paid to test a HP. They drop at 30 gr. in pure lead, and just under 20 gr. in pure tin. FPS was equal to similar weight lead pellets, from a Benjamin Genesis NP rifle, shots were under a nickel at 20 yards. I'm not sure how well a .177 or smaller slug would do.
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Pure tin is about BHN 10, certainly not too hard for airgun use.... but would be a bit harder to swage than lead.... There are two components to BC, the Sectional Density and the Form Factor.... If you have two slugs with identical weight and outside shape, they will have the same BC.... Making one from tin and the other from lead with internal hollows will make NO difference to the BC....
Peter is correct, if you reduce the density, and hence the SD, for the same shape you will lose BC.... Tin is 65% the weight of lead.... There have been several guys who have tried casting in pure tin with good success.... The caveat is that the less dense slugs will require a faster twist rate to stabilize, so if your barrel is marginal for a given bullet with lead, you may need a faster twist rate for that same bullet in tin.... Hybrid (hollow lead) slugs will not see as much effect from their reduced weight, because the lead is concentrated around the outside of the slug, increasing its "moment of inertia" in spin, to be more like a solid lead slug....
One thing about the new hollow "Hybrid" slugs.... If you compare the same weight in solid lead or with internal cavities, the Hybrid will end up longer and sleeker for the same weight, which should result in a bit better FF.... Since BC = SD / FF, then the Hybrid should also have a bit better BC than the same weight solid slug of the same caliber and nose shape.... The same, of course will apply to tin slugs.... For the same weight, they will have a better BC than the same nose shape and caliber in lead, because they would be longer, with a better FF....
Bob
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Bob
Thanks for eeeexcellent explanation. I was thinking also about better moment of inertia in spin but I was not sure because at pellets it is contrariwise for better long range accuracy.
The question only is which way will be easier/less expensive ( barrels + slugs ) for very accurate .142/11FPE/800-950FPS shooting at 100 yd.
1. 5,4- 7,5 gr - longer tin slugs
2. 5,4- 7,5 gr - longer hollow core lead slugs - FX design
3. 5,4- 7,5 gr - shorter not hollow core lead slugs - Corbin design
4. 5,4- 7,5 gr - longer hollow core lead slugs - not FX/Corbin design – hollowed from tail side
Just now I am thinking about theoretical/future mass production not private project.
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IMO, for "very accurate", with the difficulty of casting such a small pill, you need to swage.... I think tin MAY be a bit too hard to swage, and #1 is certainly more expensive.... Generally, slugs (aka bullets) want to have the CG aft, so the #4 hollow base design MAY not be the best choice.... That leaves choices #2 or #3.... I think the FX style slugs can be made with Corbin dies (and I am pretty sure the prototypes were)…. but they require multiple strokes of the press to make the large HP cavity, shape the nose, and make the HB.... and also more expensive die sets.... The least expensive would be #3.... but IF you found the magic combination then #2 might provide a slightly higher BC....
Bob
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Thinking outside the box...if the purpose is hunting, could you just use smoothbore barrel and shoot 3 tin roundballs per shot? Then you'd get a little bit of spread and won't have to worry about twist rate.
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Very limited range, accuracy, and impact, however....
Bob
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IMO, for "very accurate", with the difficulty of casting such a small pill, you need to swage.... I think tin MAY be a bit too hard to swage, and #1 is certainly more expensive.... Generally, slugs (aka bullets) want to have the CG aft, so the #4 hollow base design MAY not be the best choice.... That leaves choices #2 or #3.... I think the FX style slugs can be made with Corbin dies (and I am pretty sure the prototypes were)…. but they require multiple strokes of the press to make the large HP cavity, shape the nose, and make the HB.... and also more expensive die sets.... The least expensive would be #3.... but IF you found the magic combination then #2 might provide a slightly higher BC....
Bob
I add interesting link about JSB Lead free pellets .177/6.8gr
https://www.youtube.com/watch?v=kYjLFZstHbM (https://www.youtube.com/watch?v=kYjLFZstHbM)
Machining instead swaging lead free/tin? pellets/slugs would be probably too expensive.
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Drilling 3mm*4,5mm hole in to the .177 H&N Rabit magnum decrease the weight from 15,7gr to 5,4gr and pellet/slug will be also a little bit shorter too. BC should be still two times better then tin BC for tin pellets.
Or should be better to wait when H&N start swage the holes ?
https://www.merkuria.net/diabolky-kal-4-5-mm/1223-diabolky-h-n-rabbit-magnum-pre-extra-silne-vzduchovky.html (https://www.merkuria.net/diabolky-kal-4-5-mm/1223-diabolky-h-n-rabbit-magnum-pre-extra-silne-vzduchovky.html)
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=.24&nose=.06&meplat=.12&drive_band=.177&base_diameter=0.177&angle=0&boat_tail=0&secant_radius=30&weight=16.5&density=11.4 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=.24&nose=.06&meplat=.12&drive_band=.177&base_diameter=0.177&angle=0&boat_tail=0&secant_radius=30&weight=16.5&density=11.4)
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Hollowed .177 H&N Rabit magnum BC=0,02
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=.23&nose=.12&meplat=.12&drive_band=.177&base_diameter=.177&angle=0&boat_tail=0&secant_radius=&weight=6.4&density=4 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=.23&nose=.12&meplat=.12&drive_band=.177&base_diameter=.177&angle=0&boat_tail=0&secant_radius=&weight=6.4&density=4)
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Why hollow core lead FX hybrid slugs have so good BC=SD/FF=0,08 ?
Because they are as long as much heavier slugs. A projectile needs length to reduce the shock to air flowing into, around and over it. The slugs are long for their weight because of the large hollow space inside.
EDIT: Oops. I am late to the party. Question has been answered already.
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Drilling out a pellet to lighten it will DECREASE the BC in proportion to the reduction in weight.... If it is half as heavy, it will lose half the BC.... assuming you don't change the outside shape....
Bob
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Peter,
you're looking for .177 slugs for guns with low power. This means, light slugs.
The lightest in .177 I have found are the GRIFFIN SLUGS.
Ebay seller name = cheesehead1990
With a hollow base: From as light as 10gr(!). 14c a shot
https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Hollow-Base-10-19-gr-100-Ct/183961827831?hash=item2ad4fab9f7:m:m-eVy0M7fhGej4HclptTjww (https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Hollow-Base-10-19-gr-100-Ct/183961827831?hash=item2ad4fab9f7:m:m-eVy0M7fhGej4HclptTjww)
With a dish base: From as light as 13gr. 14c a shot
https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Dish-Base-13-20-gr-100-Ct/174035336280?hash=item2885507c58:m:m-eVy0M7fhGej4HclptTjww (https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Dish-Base-13-20-gr-100-Ct/174035336280?hash=item2885507c58:m:m-eVy0M7fhGej4HclptTjww)
With a flat base: From as light as 13gr. 14c a shot
https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Flat-Base-13-22-gr-100-Ct/183961814228?hash=item2ad4fa84d4:m:m-eVy0M7fhGej4HclptTjww (https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Flat-Base-13-22-gr-100-Ct/183961814228?hash=item2ad4fa84d4:m:m-eVy0M7fhGej4HclptTjww)
With a boat tail: From as light as 16gr. 15c a shot.
https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Boat-Tail-16-24-gr-100-Ct/183961838401?hash=item2ad4fae341:m:m-eVy0M7fhGej4HclptTjww (https://www.ebay.com/itm/GRIFFIN-Lead-Air-Gun-Slugs-Pellets-177-Cal-Boat-Tail-16-24-gr-100-Ct/183961838401?hash=item2ad4fae341:m:m-eVy0M7fhGej4HclptTjww)
The seller's explanation of the different bases of the slugs:
Hollow base is for moderate power guns.
Cup base is for moderate to high power guns, it is a little more forgiving.
Dish base is for high power, mostly pcp guns. (FX Crown loves them)
Boat tail and flat base are for the highest power guns.
Shipping to Slovakia
I only see shipping to the US on Ebay. But if you contact the seller you might be able to work something out.
If not, let me know, I can ask a friend to ship it from the US to you, or from Germany like we did the last time (but we'll need several months of time to make this happen, I won't be in Germany till the middle of next year.
Matthias
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Drilling 3mm*4,5mm hole in to the .177 H&N Rabit magnum decrease the weight from 15,7gr to 5,4gr and pellet/slug will be also a little bit shorter too. BC should be still two times better then tin BC for tin pellets.
Or should be better to wait when H&N start swage the holes ?
https://www.merkuria.net/diabolky-kal-4-5-mm/1223-diabolky-h-n-rabbit-magnum-pre-extra-silne-vzduchovky.html (https://www.merkuria.net/diabolky-kal-4-5-mm/1223-diabolky-h-n-rabbit-magnum-pre-extra-silne-vzduchovky.html)
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=.24&nose=.06&meplat=.12&drive_band=.177&base_diameter=0.177&angle=0&boat_tail=0&secant_radius=30&weight=16.5&density=11.4 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=.24&nose=.06&meplat=.12&drive_band=.177&base_diameter=0.177&angle=0&boat_tail=0&secant_radius=30&weight=16.5&density=11.4)
The Rabbit Magnums are perhaps the worst projectile that I have ever shot out of airguns. Bad to the point of not being able to keep them in a 12" x 15" target box at 45 yards.
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As always, many try to shoot slugs thru a barrel without slugging the bore, and selecting a projectile that properly fits it. If accuracy is that bad, the bullet is under sized for the bore.
always slug the bore, and select or size to bore or choke if present. No more that .0003 to .0006-7 over groove dia.
Never depend on manufacturers published figures. They are almost alway incorrect. Often by a large margin. ;)
Knife
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I hate to burst your bubble some, but the FX slugs weigh 22 grains. They are also a tight fit in the gun that I'm testing (a springer) them on. The gun normally shoots about 15-16FPE. I'm only seeing about 480 fps, which translates to about 12 FPE. I'll be testing expansion today, but I would suspect that you may need as much as 700-800 fps on target to get proper expansion.
As Mod90 correctly stated, tin is harder than lead. I doubt that I would even be able to chamber a tin equivalent of the FX slug.
Update: I'm finishing up the testing on the FX slugs, and they don't expand at all at a velocity on target of 480 fps. They do expand at 860 fps(velocity on target) (36FPE). Don't expect them to expand well out of lower power PCPs.
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Sorry Mr Wall, but that simply is NOT a slug gun. Not even close. The platform is the foundation needed before anything else.
Simply a non starter. ;)
Knife
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WOW Mathias,
I want to taste all (4) types of lightest for sure – I will try contact seller.
Next year offer is also very interesting for me. May be I will contact you at springtime.
I also have contacted H&N whit ask to produce lighter ( 5-8gr ) .177 slugs with large and deep hollow point made from lead or from tin.
A lot of people own/prioritizing low power AGs or want to save environment.
Peter
Mike,
Your experiences are very important fore sure. Unfortunately sometimes I do not understand your explanation probably because I am very bad at English .
In my knowledge and in my words the lines creating at slugs by rifling lands have to be shallow and narrow us much as it is enough for spinning and grooves diameter have to be the same or a littleeeee bit smaller as slug or bands OD. The band at base on .177 Rabit Magnum is about 4,6-4,7 mm and yes they are also very inaccurate from all of my PCPs.
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LAte to the party....so I have to ask..other than a legal restriction on lead:
What advanatge does tin it offer (besides not-lead)?
Know us shotgunners got use to steel shot where required (plus points for the makers in getting those loads up to a passing grade from a pretty horrid start)....know I've surviced lead free indoor firearms ranges...but likely I will have to soon have to (eventually in my location) have to survice lead free airgun ammo too?
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Know that over the long years,lots of trys at non-lead projectiles have been tried. Still have some "Gallery" .22 shorts that are stintered iron in a plastic/glue compressed matrix(which is the same as the BB Dustdevils..and not something I'd recommend for barrel life/accuracy in a rifled bore...but when where carnivals concerned with not giving out enough stuffed anuimals?)=)...have tried the .22LR CCI's that are the same thing with a copper powder...sabat ammo (with whatever metal you want as the sabot is the only thing that touches the bore)....pure copper bullets (in center fire)....steel shot...bismuth shot..cast Kerksite (basically a Zinc alloy)...etc.;
Whatever comes....I'll adapt...but util it is REQUIRED...am sticking to lead...pellets/slugs/or ball.
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Ribbon, the ONLY reason, from a performance point of view, to use tin.... is that because it is only 65% the density of lead, for the same WEIGHT projectile a tin one will have a longer, sleeker shape, and hence a better BC.... This doesn't work for shot, or for replacing the same SHAPE projectile in lead with tin, copper, steel or aluminum, because the BC would decrease in proportion to the (reduced) weight....
The Ballistics Coefficient is comprised of two factors, Sectional Density (weight divided by caliber squared), and the Form Factor (dependent on the Drag Coefficient), related by the formula BC = SD / FF.... Two projectiles of the same caliber and weight will have the same SD, regardless of the material.... However, the lighter material, for the same weight, will have to be formed into a longer projectile, and therefore can have less drag (and a lower FF)…. If the SD is the same and the FF is less, then the BC will be better.... On the other hand, if you have two projectiles of the same shape, they will have the same drag, and hence the same FF.... The lighter one will have a lower SD, and therefore a lower BC....
I'll give you an example.... Lets start with this slug, made from lead.... It weighs 65 gr. and has an SD of 0.140.... The FF is 0.955....
(https://i378.photobucket.com/albums/oo221/rsterne/NOE%20Bobs%20Boattails/257-65-FN_BT__65_gr_Sketch_zpscxjglucj.jpg) (http://s378.photobucket.com/user/rsterne/media/NOE%20Bobs%20Boattails/257-65-FN_BT__65_gr_Sketch_zpscxjglucj.jpg.html)
Now let's see what a 65 gr. slug made from tin would look like, with the exact same SD of 0.140.... The FF is 0.676....
(https://i378.photobucket.com/albums/oo221/rsterne/NOE%20Bobs%20Boattails/257-100-FN_BT_102_gr_Sketch_zpsfkvdlxo3.jpg) (http://s378.photobucket.com/user/rsterne/media/NOE%20Bobs%20Boattails/257-100-FN_BT_102_gr_Sketch_zpsfkvdlxo3.jpg.html)
That slug would weigh 100 gr. if made from lead, and you couldn't shoot it at anything like the same velocity that you could get with a 65 gr. slug from a given PCP.... However, if you cast it out of tin, it would only weigh 65 gr. and you could drive it at the same velocity as the short, stubby slug above it.... There is NO question which slug has less drag.... The long, sleek tin slug, with about 30% less drag, would win hands down....
Bob
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Just flying partly blind here.
Saying that the density part of the twist rate equation s worth less than the length...or the other way around?
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Sorry Mr Wall, but that simply is NOT a slug gun. Not even close. The platform is the foundation needed before anything else.
Simply a non starter. ;)
Knife
I totally agree!!! This particular springer just happens to be a comparison test platform that we use. Wouldn't even consider using it in real life!
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Yes, a faster twist rate will be required for the long tin slug.... However, the FPE loss is very small to produce the extra RPM required to stabilize it....
http://bulletin.accurateshooter.com/2015/02/does-barrel-twist-rate-affect-muzzle-velocity-litz-test/ (http://bulletin.accurateshooter.com/2015/02/does-barrel-twist-rate-affect-muzzle-velocity-litz-test/)
In actual measurements by Bryan Litz, the velocity change was smaller than the SD....
Bob
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OK...good to check what I assumed about twist/length vsjust weight.
Didn't even consider the energy going into faster rotation....but as you mention, it's not enough to matter (or even notice).
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Checking is always necessary.
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Made from Tin + hollowed may be longer and may be probably producing by machine automat.
Barrel rifling can be shallower because the tin is harder then lead. For low power shooting we can also stay at caliber .177.
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=0.5&nose=.3&meplat=.06&drive_band=.177&base_diameter=.177&angle=0&boat_tail=0&secant_radius=&weight=9.8&density=3 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.177&length=0.5&nose=.3&meplat=.06&drive_band=.177&base_diameter=.177&angle=0&boat_tail=0&secant_radius=&weight=9.8&density=3)
Whit the same TR=6 we can also shoot four time heavier the same profile slugs made from lead without hollow but rifling have to be rather whit narrower lands as shallower groove.
It seams that Slugs/bullets let us more variation then pellets just we need custom barrel whit faster twist rate.
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I don't want to hijack this thread, but when are we going to start to see some injection molded polymer/copper pellets/slugs, like the ARX bullets? Might be interesting.
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When I first read the title of this,though someone was going to try Abe Flatau's "ring airfoil"tubular projectile once again. Not really his (most of thework he did was on the 37mm grenade launchers)...when I did reservh it, found designes as early as the 1890's for a "tubular"bullet (the hole in the middle was suppose to do wonders for the BC)...but the "pusher"wad needed to seal it and then drop away was always a problem.
Don't know when they first stated making stintered/poly bullets....1930's?1940'? for some .22 ammo. Stintered lead then stintered iron; most mostly used for carnival type shootinggally use, where accuracy or even mostly worn out rifing wasn't a concern (after all,they didn't want to give out any more stuffed animals that they had to).
Did notice CCI had stintered copper ammo announced recently(haven't tried it)....and the "Dust Devils"are the BB incarnation of the old stintered iron idea.
All things considered, not really sure it would make for great airgun ammo....but then again, it's likely not really any harder that tin and there are tin-pellets.
Sabot ammo has been tried in airguns once(SABO), and there are several plastic/metal pellets (although as the plastic doesn't drop away,it's really not a sabot...just a thick plastic jacket).
Does seem that airguns haven't had alot of innovation tried (yet).
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We know that lead create good inertia of spin and mass have to be rather at rear of slugs/bullets.
What about to do 3R Jacked from lead on reversed spire from aluminum for low power long range shooting ?
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Lead jacketed aluminum slugs? Not a bad idea. Would be lighter, and could be made longer or shorter as necessary. The lead jacket will give the rifling something to grab onto.
Even better, a hollow lead slug filled with tin. Might make a wicked hunting round.
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Yes but “Variations in the size of the large flat areas (meplat) at the front of many of them coupled with the detail shape at the edges of the meplat. Very small amounts of rounding on the edges can have a large effect on the drag coefficient as well as the aerodynamic stability.
“
see https://www.gatewaytoairguns.org/GTA/index.php?topic=166147.40 (https://www.gatewaytoairguns.org/GTA/index.php?topic=166147.40)
Aluminium point can ovoid this problem
http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.142&length=.35&nose=.2&meplat=.02&drive_band=.142&base_diameter=.142&angle=0&boat_tail=0&secant_radius=&weight=4.3&density=5 (http://www.geoffrey-kolbe.com/cgi-bin/drag_working.cgi?unit_length=inches&weight_unit=grains&bullet_name=Custom+bullet&re_calculate=yes&boundary_layer=L%2FT&diameter=.142&length=.35&nose=.2&meplat=.02&drive_band=.142&base_diameter=.142&angle=0&boat_tail=0&secant_radius=&weight=4.3&density=5)