Question about axial stability

Status
Not open for further replies.
Not sure what you're getting at here. Most handgun bullets stabilize well in most handguns so long as bullet diameter and bore diameter are matched and common loading practices are followed.

What distance are you expecting to shoot? Unless you are into metallic silhouette shooting at ranges up to 200 meters, you will experience good accuracy from just about any decent handgun/ammunition combination.

The bullet you show in the illustration seems poorly constructed. There seems to be air space at the base of the bullet and the jacket. The jacket seems to be fairly thick, and is enclosed within the case mouth, leaving the case mouth crimped on the bullet core. Seemingly the core is "black steel" or maybe sintered iron? Looks to me to be likely to shed its jacket in the bore. Why does it not cover the entire cylindrical bearing surface?

Please elaborate further on your requirements.

Bob Wright
 
Last edited:
O.K. I did a little further research on that round. It is a custom made armor piercing round. The core is lathe turned hardened steel while the "jacket" actually serves as a sabot.

As to stabilizing that bullet, it seems the sabot is too short and all accuracy would be lost, or pretty much so, even as that bullet travels down the bore. And shedding the sabot would likely cause further tumbling of the core.

I seriously doubt any degree of accuracy, and as to the armor piercing capability it would only be useful at very close range, and that against body armor. Looks to me to be a totally useless round.

Bob Wright
 
poor .357 it's just an example. I mean what is the minimal shortest length cylindrical part any cone nose bullet(let's say solid bullet) of its total length?
 
Most revolver bullets, and I believe most rifle bullets as well, all of the bullets diameter short of the ogive is a bearing surface, with the exception of boat tail rifle bullets. And the greater the bearing surface, the better the accuracy of a bullet. Consider the wadcutter target bullets, which have the entire length of the bullet as a bearing surface. And saboted muzzle loader bullets, the sabot nearly completely encloses the bullet.

The bearing surface is of extreme importance contributing to accuracy. Without the stabilizing influence of a long bearing surface, the bullet will attempt to gyrate, its nose scribing a circle around its centerline.

Bob Wright
 
BobWright said:
Looks to me to be a totally useless round.
Click to expand...

I think you answered your own question...

What is the shortest caliber projectile? A sphere.
Why don't we commonly use spheres in modern firearms?
1. If you push a sphere to fast it becomes unstable,
2. and it does not penetrate well.
3. The lack of bearing surface in the bore causes the sphere to lose rotational stability at longer range.

OK, then take a baseball, carve cavities front and back, and assume you can rotate it effectively for stability; throw it. What's likely to happen?
 
Olofff said:
Of cource axial stability with diameter/bearing surface lenth much more ratio, must be better! No dubt.
But if we have big lenth -we have big weight. For handgun bullets - this may be a problem.
Why not have hole in ass for all short bullets? ( see link)
http://www.municion.org/9para/ThvG.jpg
http://www.guntree.co.za/cache/images/bc71192ce9bccee805f3f90e7f01564d.jpg
Problem in pressure on the bullet skirt and high friction through it on the barrel?
Click to expand...

I'm sorry, but about here we I just need to step back and ask what the designer is trying to achieve. What do these bullets offer that is not already obtained using conventional bullets, especially in the realm of pistol and revolver bullets?

If the goal is armor piercing, that has already been covered by AP bullets, and when the necessity of AP is required, better arms are available at that level, i.e. penetrating light armored vehicles or personnel armor.

Extend range? Most magnum revolvers and pistols offer power and accuracy out to 200 meters or more, again using conventional ammunition.

Right now I'm asking, what's the point in all of this?

Bob Wright
 
The goal is experiment with custom .309 AP in the range of 45-55 grain (without use sabot).
Such .309 I have not seen.
 
A .309" diameter bullet weighing 45~55 grains? And to pierce armor? Won't happen.

For armor piercing, its hard to beat the .30 caliber M-1 Garand loaded with M2 AP cartridges.

Seems to be you're kind of shooting up the wrong barrel.

Bob Wright
 
Two requisites for penetration are velocity and sectional density.

I believe some laboratory once made a Styrofoam ball penetrate a steel plate to a depth of half its diameter when driven to some astronomical velocity. And archers demonstrate that an arrow shot from a compound bow will penetrate deeper into sand than a .30-06 rifle bullet. Cases of velocity and sectional density.

Achieving penetration is dependent upon a balance of these two factors, neither of which are conducive to minimal recoil. First of all, define what type of armor you are trying to defeat, and at what range, then develop the cartridge, bullet and weapon to accomplish the task.

Bob Wright
 
First of all, thank you for the answers.

I think CZ-52 with its powerful cartrige is very promising for AP. Especially 45-50 grain bullet with steel core. 3000 velocity is quite real people talk.
 
Olofff said:
First of all, thank you for the answers.

I think CZ-52 with its powerful cartrige is very promising for AP. Especially 45-50 grain bullet with steel core. 3000 velocity is quite real people talk.
Click to expand...

Please post photos, videos if made, when this is done. Most interesting. Especially the gun and armor penetrated.

Bob Wright
 
The Armor (as in tank/panzer) people have worked out that the ideal armor penetrator has a 1:12 or 1:17 diameter:length ratio.

So, a 50mm projectile winds up being 600mm long. To get that projo up to around 1500m/sec needs a sabot to get the base up around 120-125mm.

The match works the other way as well. A 1mm projo will need to be 12-17mm long. Which would probably need a sabot to get up to around 1000m/sec. Tough part is finding a material which will not bend at those velocities. Bronze machines well, but tungsten has a better penetration index (but is a huge pain to machine along with being expensive).

I am probably misremembering, but I want to remember M. Minié used 1:1.161 for bore to flat ratio.
 
Bob Wright, please just find 7,62x25 load data subject.
CapnMac, hardened high-carbon steel and copper plating main idea.
But I not understand, you talk 9mm luger must have 4.25"(1:12) cylindrical part(bearing surface) of full bullet lenght ??
 
I read that the maximum L to D ratio for a spin stabilized projectile is 5:1.
The long anti-tank "dart" rounds CapnMac mentions are fin stabilized from smoothbore barrels.
A fletchette firing small arm can be made to work, but fitting it into the 9mm P cartridge and gun does not look feasible.
 
I think your goal of getting something AP to work with a 9mm platform is going to be a frustrating and ultimately unsuccessful endeavor, especially if you are trying to maintain the 9mm bore.

While I don't have the ballistics knowledge exuded by CapnMac, if you look at what cartridges ultimately have had AP rounds built for them or ones that are used in that capacity you will find that something like a 9mm simply does not have enough case capacity or SD to generate that kind of penetration you would need for AP. Sure you can do a small caliber projectile with a discarding sabot to get the SD of your projectile lower, but now you have to deal with a projectile significantly smaller than the bore which means you need a much larger, relatively speaking, sabot. This presents numerous problems specifically in that to find a material that will be tough enough to engage the rifling and not skid over the lands, rigid enough given it's relative thickness to hold the projectile secure and centered in the bore, but be light enough so as not to expend the limited energy you have on accelerating mass for something that will be discarded after leaving the muzzle (energy you throw away). You may be able to achieve something that is partially workable, however I suspect that the reliability will be poor at best and accuracy will never be there. Even the 30.06 accelerator rounds (.22 bullet in a 30.06 case with a discarding sabot) while very fast were never known as being very accurate.

Take a look at the 5.7x28 or the 22 TCM cartridges to get a better platform for getting your velocity up to where it needs to be. These bottle necked cartridges already have some pretty impressive velocities from pistol size platforms and have a good SD to boot.
 
Jim Watson said:
A fletchette firing small arm can be made to work, but fitting it into the 9mm P cartridge and gun does not look feasible.
Click to expand...
This is a complicated thread for being highly technical, and needing to be easily translatable from English.

Now, there was a prototype flechette 9x19 round. If memory served it was a 2 or a 2.25mm diameter dart right at 23mm long. The flechette actually sat on the primer anvil, and used a nylon sabot in the shape of a 115gr FMJ. The testing revealed problems with the sabot not separated cleanly, or fracturing too soon (in the barrel) which released the propellant gasses too soon. Tumbling flechettes are not good. They apparently experimented with a teflon-to-teflon sleeve from the sabot to the barrel usig a sleeve about 4 mm long (or similar to the bearing surface on an FMJ).

Oh, and the bore flat on cast bullets for RNL 9x19 is 0.165" or 4.191mm. FMJ are 15.8mm long overall.
 
Status
Not open for further replies.

Similar threads

B
  • Locked
Forstner Co-axial press review
Replies
12
Views
1K
JimKirk
JimKirk
G
  • Locked
Basic question about compensators/muzzle brakes
Replies
3
Views
179
mcb
mcb
hso
  • Locked
ATF Stabilizing Brace "Objective Factors" Open Comment Period
Replies
20
Views
2K
vintovka
vintovka
D
  • Locked
Odd question about bullets...
Replies
8
Views
1K
BHP9
B
L
  • Locked
help me understand something about cartridge length and seating depth
Replies
8
Views
617
Dudedog
Dudedog
Back
Top