Question on point form dies

[guywitha3006]

Thank you everyone for all the patience and explanations as I figuring the swaging thing out. How does the point form die work, I get the basic push lead/copper into a shape; the question I have is it possible to change the shape of the bullet without a completely new die(such as changing an insert)? I ask because when I move into the .30 cal setup I am looking to make 3 fairly different profile bullets (at least I think they are different) I am thinking a light weight one that is similar to the Barnes .300 Blackout bullet (110-130 grain range), 168-175 grain SMK clone, and a 200-240 grain SMK clone (these may have the same shape just elongated?). Also does anyone have a good reference for explaining profile such as the difference between a 6s or 8s?

[IllinoisCoyoteHunter]

Elongating the same design is possible by changing jackets and core weight. Changing the profile with a single die, short of going from a fp to a hp, would be a challenge. I am sure someone has done it but normally it is one die, one profile.

The ogive is measured in calibers. For example a 6s ogive is a curve coming off the bearing surface made from a radius of 6 times the diameter (caliber). The radius starts perpendicular to the bearing surface and creates and arc. Higher number ogives have a longer arcs, therefore longer nose profiles.

For example for 22 Cal a 6s ogive would be an arcade from a radius of 6 X .224.

Get it?

When swaging lead slugs different punches will give different nose profiles.

[jimrk]

Richard and Dave Corbin have good info on their sites.. these links are to RCE

http://rceco.com/img/RSBook12.pdf
http://rceco.com/img/RSBook9.PDF

[guywitha3006]

That is what I was thinking for the point/bullet shape. That 6s description makes sense, I tried figuring it out looking at the Corbin brothers info, but for some reason my math brain has taken a few days off. 6s=arc of 6x.224 (for .224 makes sense).

Any idea what the typical ogive is for .30 and .22 caliber target bullets? SMKs would be even better! :)


Elongating the same design is possible by changing jackets and core weight. Changing the profile with a single die, short of going from a fp to a hp, would be a challenge. I am sure someone has done it but normally it is one die, one profile.

The ogive is measured in calibers. For example a 6s ogive is a curve coming off the bearing surface made from a radius of 6 times the diameter (caliber). The radius starts perpendicular to the bearing surface and creates and arc. Higher number ogives have a longer arcs, therefore longer nose profiles.

For example for 22 Cal a 6s ogive would be an arcade from a radius of 6 X .224.

Get it?

When swaging lead slugs different punches will give different nose profiles.

[IllinoisCoyoteHunter]

I think most target 22 Cal bullets are 7s?? I might be wrong. As for 30 cal you should figure out which weight /design you barrel twist rate likes first...then worry about making/ordering dies. Heavier bullets are generally longer and have a longer nose...especially high BC low drag bullets.

Understand and study the different types of ogives...tangent, secant, and hybrid. They all have their pros and cons.

If you want to make dies, know for sure what your rifle likes first.

[guywitha3006]

Thanks for the info, I mention SMKs because that is what I currently use. I wish I had the skills to make my own dies but I do not know much if anything of lathes. The plan is to buy the dies I need from Corbin/BT/ect. Hopefully someday I will get a lathe and figure out how to use it, a mill would be nice too... again this site is going to cost me a lot money.


I think most target 22 Cal bullets are 7s?? I might be wrong. As for 30 cal you should figure out which weight /design you barrel twist rate likes first...then worry about making/ordering dies. Heavier bullets are generally longer and have a longer nose...especially high BC low drag bullets.

Understand and study the different types of ogives...tangent, secant, and hybrid. They all have their pros and cons.

If you want to make dies, know for sure what your rifle likes first.

[tiger762]

You might find this helpful:

143278

[guywitha3006]

I say that before, but it makes more sense. Where would the VLD fall into thing, those are tangent ogives at that point right?


You might find this helpful:

143278

[IllinoisCoyoteHunter]

Tangents make a smooth transition from bearing surface to ogive while secant ogives are more abrupt. The arc starts further back and slightly above the bearing surface ( but still perpendicular ). Hybrids are a combination of both. Bearing surface to tangent to secant, in that order. Allows for best bullet alignment in thr bore while keeping the BC up.

Generally secant ogives give the best BC. Don't know much about hybrids but they are probably up there too.

[aaronraad]

As IllinoisCoyoteHunter (http://castboolits.gunloads.com/member.php?8392-IllinoisCoyoteHunter) described above tangent ogives start tangent to the calibre of the projectile (or shank) that is nominally assumed to be the main parallel section riding the bore. Secant ogives are basically tangent ogives pulled back (offset) a set distance and then pushed up until they intersect with the shank again.

Corbin(s), Litz and Fr. Frog use a ratio to describe the amount of secant applied. The ratio works as the radius of the ideal tangent versus the radius of the actual ogive. See Fr. Frog's Miscellaneous Questions webpage - http://www.frfrogspad.com/miscellw.htm#nose

If the actual ogive is tangent then the ratio will be 1:1 (or 1/1 = 1). The ratio describing the when the maximum amount of secant offset is applied is 1:2 (or 1/2 = 0.5). Effectively this means the most you can offset a 12s ogive is equivalent to the length of an ogive made using an ideal 6s tangent for the equivalent calibre. It helps if you can practice drawing/sketching the full or semi-circles made by a few of the different radii for the same calibre. If you don't have a CAD program try some transparent tracing paper drawing the ogive on the larger of the two cut-outs and overlap them to see the effect.

[guywitha3006]

I was playing with autocad and comparing different profiles, along with measuring some Sierra Matchkings (168,200, and 220) they all seem to have a very similar ogive but I could not tell if they are exactly alike. I also looked at frfrodspad's page/ chart and it seems the Matchkings fall in around an S8 or S10. Am I on the right track or way off playing a different sport? I am thinking I will want something 8S, 10s, or a VLD design. Its a big investment so I want to know as much as possible before I settle on a profile. I will be loading 308 Winchester (165-178 range) and 300 Blackout (primarily subsonic if I had to choose one, but light weight 110-130s would be nice). I can't wait to actually start smashing some lead and copper together. :bigsmyl2:




As IllinoisCoyoteHunter (http://castboolits.gunloads.com/member.php?8392-IllinoisCoyoteHunter) described above tangent ogives start tangent to the calibre of the projectile (or shank) that is nominally assumed to be the main parallel section riding the bore. Secant ogives are basically tangent ogives pulled back (offset) a set distance and then pushed up until they intersect with the shank again.

Corbin(s), Litz and Fr. Frog use a ratio to describe the amount of secant applied. The ratio works as the radius of the ideal tangent versus the radius of the actual ogive. See Fr. Frog's Miscellaneous Questions webpage - http://www.frfrogspad.com/miscellw.htm#nose

If the actual ogive is tangent then the ratio will be 1:1 (or 1/1 = 1). The ratio describing the when the maximum amount of secant offset is applied is 1:2 (or 1/2 = 0.5). Effectively this means the most you can offset a 12s ogive is equivalent to the length of an ogive made using an ideal 6s tangent for the equivalent calibre. It helps if you can practice drawing/sketching the full or semi-circles made by a few of the different radii for the same calibre. If you don't have a CAD program try some transparent tracing paper drawing the ogive on the larger of the two cut-outs and overlap them to see the effect.

[IllinoisCoyoteHunter]

If you go with a VLD design or a higher ogive be mindful with the lighter weight bullets you will not have much bearing surface. The ogive of the bullet remains constant, and the length of the bearing surface dictates your weight (you will use longer jackets with heavier cores for the heavier bullets, and shorter jackets with lighter cores for the lightweight bullets).

[guywitha3006]

If you go with a VLD design or a higher ogive be mindful with the lighter weight bullets you will not have much bearing surface. The ogive of the bullet remains constant, and the length of the bearing surface dictates your weight (you will use longer jackets with heavier cores for the heavier bullets, and shorter jackets with lighter cores for the lightweight bullets).
Thanks for the insight, I had thought about the esteem spread that would be nice and thought of it will be feasible. If I can't make lighter then 150a it's not to big a deal I would be more worried if I could only make 1 of the 3 weight ranges but honestly 165-220 would cover about 95% of my .30 caliber needs and I can make ~168 trainers work for the other 5%. There is a lot of thinking going into this, maybe more then I expected but I enjoy learning new things so it is working out.

[aaronraad]

Thanks for the insight, I had thought about the esteem spread that would be nice and thought of it will be feasible. If I can't make lighter then 150a it's not to big a deal I would be more worried if I could only make 1 of the 3 weight ranges but honestly 165-220 would cover about 95% of my .30 caliber needs and I can make ~168 trainers work for the other 5%. There is a lot of thinking going into this, maybe more then I expected but I enjoy learning new things so it is working out.

S10 would be my choice for a long range target all-rounder. S8 would be better for mid-to-lower weight choices with the option of short range BR work where 30 cal is concerned. VLD's are much better off left to the mid-higher weights, but you really need very long dies (+3") to support boat-tail punches properly to the best of my understanding and experience so far.

Meplat diameters should not be overlooked if BC and hunting applications are a concern. It's all proportional, so tipping a 0.082" meplat down to 0.055" for a 30 cal projectile makes a big jump in BC, but not so much in a 50 cal projectile.

[guywitha3006]

Aaronraad, thanks! that is what I was thinking and looking for. My biggest reason for wanting to swage .30 cal in the first place is to make 200+ grain target bullets (don't see enough deer to feel the urge to load hunting ammo at the moment, lol) to use in my 300 blackout sbr (suppressed so I wanted to get away from cast for this particular application). My next use would be for 308 Winchester for 2-300 yard plinking (165-178 range).


S10 would be my choice for a long range target all-rounder. S8 would be better for mid-to-lower weight choices with the option of short range BR work where 30 cal is concerned. VLD's are much better off left to the mid-higher weights, but you really need very long dies (+3") to support boat-tail punches properly to the best of my understanding and experience so far.

Meplat diameters should not be overlooked if BC and hunting applications are a concern. It's all proportional, so tipping a 0.082" meplat down to 0.055" for a 30 cal projectile makes a big jump in BC, but not so much in a 50 cal projectile.