50cal bullet design...

[Dylanss180]

Taking overkill to a whole new level.

many many reasons

1. no available match grade powders slow enough to launch a bullet that heavy (possible some military pull downs but nothing readily available, easily accessible or of the quality to match the quality of cnc brass solid)
2. a bmg case is not large enough to carry an adequate powder charge for a bullet that heavy (a charge of 250 grains of Reloader 50 doesn't fill it but there is not much room left)
3. nor can it get that bullet up to a speed fast enough to stabilize
4. you would need a longer barrel than the standard long barrels of 36" to get a full burn (yes i know M2 barrels are longer than 36" but not designed for this application)
5. a brass solid projectile in .510 cant get much heavier than 820 with out getting to long to stabilize or have a decent center of gravity
6. state arms in the 90's was one of the only company's to ever offer a barrel twist of anything besides 1 in 15 and those are few and far between these days (as far as i know of)
7. there is a noticable difference in recoil from a 750 to an 800 can you imagine what a 1075 would be like
8. spend a few minutes with any of these (the miller twist rule, the greenhill formula, a drag/twist calculator) and tell me what you find
9. read Applied Ballistics by Bryan Litz and tell me what you find

i dont claim to be an expert but i have 2 - 50 bmg rifles for the last 7 years
i reload everything i shot
i have shot in 12 FCSA 1,000 yard matches in the last 6 years
ive got over 1,500 bmg rounds down range
the most ive shot was 96 rounds in 1 day due to a make-up day in the rain
my best group to date was 7-1/8" 5 shot @ 1,000 yards off the ground with a bi-pod and a sand bag
nothing great but nothing to laugh at either

ive been following this thread since the beginning and i cant believe its gotten this far
i dont know the OP "groper"
and dont want to call anyone names
but it sounds like some has spent to much time in front of a cad-cam program and not enough time behind a trigger or a reloading bench
yes they have included a few trick features of match grade custom ELR bullets but again it looks good on paper or a monitor
ask Lehigh or TenX (2 of the best brass solids on the market in my opinion) why they dont make bullets much heavier than 800 grains in brass solids

as far as bullets go i have been researching this as i have just recently started swaging my own copper jacketed lead core BMG bullets with plans to shot my bullets in next years fcsa matches

rant over for now

kd185

Thank you for giving us your insight. You defiantly have experience shooting .50s. I am no expert in ballistics but I do know some. I believe in my case I am good to go. I am in no way bashing what you have said. But let me see if I can address each of your concerns.

1: for powders, I am able to get my hands on yes military suplus powder for howitzer canons (it is not pull down. It is brand new) It is really slow stuff.
2: I am using a 20mm vulcan case necked down with approx 500 grains of powder capacity
3: I haven't completed the gun yet but I should be exceeding 3100 fps (not tested yet)
4: My barrel is 50" long
5 and 6: my twist rate is 1:10
7: yes recoil will be higher but my rig has a triple hydraulic dampner and spring system and the gun weighs 100lbs
8: With a projectile around that size a 1:11 ish twist is needed with the speeds i am hitting and I don't know how well the BC really is but time will tell.
9: I have read Litz book. It is very informative. It really shows how some bullet company's will only post G1 bc instead of G7 just because it is a higher number but it really doesn't represent it's true flight characteristics.

If you are curious here is a recent photo of my progress of building my gun. It isn't done yet but I have a .50bmg windrunner next to it to give a size comparison. The barrel isn't chambered yet. I just stuck it in the barrel shroud to give an idea of the size. There will be a muzzle break on it later.

 

[pinsandpitons]

Interesting thread, thanks.

Stupid question maybe, but I'd like to hear the reasons. Why not lead? I've never heard why these ELR type bullets aren't. Isn't a high SD critical for a good BC?

 

[kd185]

well Dylanss180
i see none of the issues i addressed real were concerns of yours as you already dealt with them
nice work by the way
but what you have is exactly my point
that bullet would never work in a stand bmg rifle
but sounds like it would work nicely in your wildcat (you are the 1% of the 1% for that market)
now the question
do you have a place to let that rig stretch it legs
because i would love to see that in action

one of the senior members of one of the ranges i belong to has built something similar

https://lh3.googleusercontent.com/-...jHLnhaO4/w422-h562-no/2012-06-09+17.31.41.jpg


https://lh3.googleusercontent.com/-...AAAAAAACdo/lTe0C1wJFhY/w640-h480-no/20mm2.jpg

 

[kd185]

You say the bullet doesnt stabilize for several hundred meters is there an equation for that?

I never said that
What i am claiming is that a modern BMG rifle will not stabalize that bullet at all

and yes greenhill and miller will prove that fact on paper

 

[kd185]

Interesting thread, thanks.

Stupid question maybe, but I'd like to hear the reasons. Why not lead? I've never heard why these ELR type bullets aren't. Isn't a high SD critical for a good BC?

i am not an expert but a well read beginner swagger and i am of of the (old school) believers that lead makes a better bullet core matter than copper, steel, brass, aluminium etc etc
so yes i agree with you
the problem is lead is not machine-able like the other metals
although i would love to play around with some tungsten powder as a core material if i hit the lottery

 

[pinsandpitons]

the problem is lead is not machine-able like the other metals

That's surprising. It seems like some alloy out there would.

 

[Dylanss180]

well Dylanss180
i see none of the issues i addressed real were concerns of yours as you already dealt with them
nice work by the way
but what you have is exactly my point
that bullet would never work in a stand bmg rifle
but sounds like it would work nicely in your wildcat (you are the 1% of the 1% for that market)
now the question
do you have a place to let that rig stretch it legs
because i would love to see that in action

one of the senior members of one of the ranges i belong to has built something similar

https://lh3.googleusercontent.com/-...jHLnhaO4/w422-h562-no/2012-06-09+17.31.41.jpg


https://lh3.googleusercontent.com/-...AAAAAAACdo/lTe0C1wJFhY/w640-h480-no/20mm2.jpg

Thanks for the compliment.
Yes you are correct I believe also that the bullet is way to big for a standard BMG. But you could shorten it up to the 750-800gr range maybe.

The gun your friend has. It looks like the Anzio Ironworks rig they sell. I was originally looking at that rig but for what you pay for it I was not impressed with what you get. I also spoke with a credible source that they didn't do any engineering in the gun. They just scaled up the size of the gun and called it good. If you want a gun in the military you have to have all the proper engineering analysis involved before they will even consider buying it. Plus I knew I could make something better but it would just take a whole bunch of my time to make it. But that is ok, I like making things.

Do you know what powder your friend uses for his rig? I spoke with someone at anzio and they like to use US869.

i am not an expert but a well read beginner swagger and i am of of the (old school) believers that lead makes a better bullet core matter than copper, steel, brass, aluminium etc etc
so yes i agree with you
the problem is lead is not machine-able like the other metals
although i would love to play around with some tungsten powder as a core material if i hit the lottery

There is steel out there wit lead alloy in it. I don't know how good of an idea that is but ill bet someone already tried it.

 

[ELR researcher]

well Dylanss180
i see none of the issues i addressed real were concerns of yours as you already dealt with them
nice work by the way
but what you have is exactly my point
that bullet would never work in a stand bmg rifle
but sounds like it would work nicely in your wildcat (you are the 1% of the 1% for that market)
now the question
do you have a place to let that rig stretch it legs
because i would love to see that in action

one of the senior members of one of the ranges i belong to has built something similar

https://lh3.googleusercontent.com/-...jHLnhaO4/w422-h562-no/2012-06-09+17.31.41.jpg


https://lh3.googleusercontent.com/-...AAAAAAACdo/lTe0C1wJFhY/w640-h480-no/20mm2.jpg

kd185:

The pics appear to be John Buhay's 20mm Vulcan. Since I know of no one other than John that has such a rifle, I'll assume it is. I've spoke at some length with John about his rifle when I was considering an Anzio 20/50. The amount of grief to shoot such a large caliber (i.e., govt restrictions) turned me away from anything larger than a .50.

There is a poster on AccurateReloading that has had a lot of experience with very large caliber cartridges and made the point quite forcefully that you really need a very large caliber projectile to get the value out of a Vulcan case - huge projectiles and very high velocities (way over 1000 gr and up to 3500 fps). Regrettably it all seems to roll back on powder and what you can legally shoot. Cost also creeps in real fast once you look into projectiles of that size - all custom.

 

[ELR researcher]

Hi Dylan:

Thanks for the update pic, a seriously awesome rifle!

If you'd be so kind, please help us understand about some of the features of your rifle and project:

1. Does the barrel float inside the sleeve?

2. What functions does the sleeve provide other than providing a mount for the bipod?

3. The weight of of your rifle appears similar to other Vulcan-based rifles (like John Buhay's) which have rather "conventional" recoil moderation devices (muzzle brakes and stout recoil pads). What moved you to add the hydraulicdampeners?

4. What weight projectiles are you envisioning driving at 3100+ fps?

5. You comment about military requirements. Is the rifle a one-off for your use or a prototype for military applications?

Thank and best wishes on your project.

 

[Dylanss180]

Hi Dylan:

Thanks for the update pic, a seriously awesome rifle!

If you'd be so kind, please help us understand about some of the features of your rifle and project:

1. Does the barrel float inside the sleeve?

2. What functions does the sleeve provide other than providing a mount for the bipod?

3. The weight of of your rifle appears similar to other Vulcan-based rifles (like John Buhay's) which have rather "conventional" recoil moderation devices (muzzle brakes and stout recoil pads). What moved you to add the hydraulicdampeners?

4. What weight projectiles are you envisioning driving at 3100+ fps?

5. You comment about military requirements. Is the rifle a one-off for your use or a prototype for military applications?

Thank and best wishes on your project.

ELR Researcher

Id be happy to answer your questions

1. The "sleeve" as you call it does not touch the barrel. The barrel free floats.
2. Basically the "sleeve" just holds the bi-pod but it consists of an inner and outer sleeve. The inner sleeve is threaded to the receiver and locked into place. It has two brackets attached to it that have sliding bushing mounts in the front of the sleeve and in the end of the sleeve. The outer sleeve also has two brackets attached to it that have two precision ground guide rods rigidly mounted to it along with the bi-pod assembly. To keep it as simple as I can the outer sleeve and bi-pod assembly are solid and just imagine that the legs are pinned to the ground and won't move. When the rifle fires the rifle will recoil and start sliding back on the guide rods. So basically instead of the bi-pods sliding on the ground the guide rods allow the rifle to slide back instead. Along with the guide rods there are springs and a damper attached to it to absorb the recoil. (There is another spring damper system in the buttstock tube on a guide rod as well) This will allow the gun to more or less stay in place for a quick follow up shot after the first one is sent without having to re-adjust the gun. If you watch a youtube video of someone shooting the 20mm version he lost the target due to the recoil. This all sounds cool when you say it but we will see how it actually works when I test it. Also, the bi-pod legs are hydraulically actuated and controlled by the shooter behind the weapon. The shooter can adjust the legs up and down behind the weapon without having to reach up to the legs. (I have a pain in the ass right now getting my windrunner bi-pod adjusted right and I wanted that feature.)

3: I think I ended up explaining that in my long winded answer in 2.

4: I am going to start with 1000ish grain but depending on how the powder i am using responds I would like to bump it up to somewhere around 1200grains. With all that powder trying to push that small of a projectile (in relative terms) I can only push it so hard. The cup pressure is my limiting factor. If I had a larger diameter projectile it would be easier to go heavier but since I can legally only go up to .5" diameter I can't go any bigger without having to go thru the red tape.

5: I have an ex military sniper really pushing me to get this thing shown to the military if it shoots good. He told me what it takes to get a contract awarded by the military. I originally intended on building this thing for myself, just because I like to make stuff. But I am unsure. I don't know if I want to deal with the hassle. We will see as time goes on. Right now this thing is just for me. This is my second gun I have built (My first one was a lot smaller) and I enjoy doing it.

Here are a few more photos for your enjoyment

 

[ELR researcher]

Hi, again, Dylan:

Thanks VERY much for your kindness in answering my questions and adding the extra pics.

I'll push my luck and pose a few more questions/requests:

1. Your profile doesn't really tell us much about you and I don't recall - but might have missed - you telling us about the kind of work you do and your skill set. Please advise.

2. One of the pics I recalled from before (months ago) on your photobucket pages was of what appeared to be a rather substantial machine shop. How is it you have access?

3. When I clicked on one of the above pics I bounced out to your photobucket page. Not having looked at it in a while I clicked through a couple pages.... Ah, please tell us about this "item" - right in the middle of pics about the current project.

Thank you, happiest of holidays, and God Bless!

Oscar (ELR Researcher)

 

[Dylanss180]

Hi, again, Dylan:

Thanks VERY much for your kindness in answering my questions and adding the extra pics.

I'll push my luck and pose a few more questions/requests:

1. Your profile doesn't really tell us much about you and I don't recall - but might have missed - you telling us about the kind of work you do and your skill set. Please advise.

2. One of the pics I recalled from before (months ago) on your photobucket pages was of what appeared to be a rather substantial machine shop. How is it you have access?

3. When I clicked on one of the above pics I bounced out to your photobucket page. Not having looked at it in a while I clicked through a couple pages.... Ah, please tell us about this "item" - right in the middle of pics about the current project.

Thank you, happiest of holidays, and God Bless!

Oscar (ELR Researcher)

Sure thing

1. I am a mechanical engineer and have been a hands on guy since I could crawl. I rebuilt my first engine before I even had a license. I work in the aerospace industry and I am currently involved with the hot section of the f-35 fighter jet engine.

2. The machine shop you are mentioning is from my work. We bought two 5 axis machines to put work in it. At the time they were just sitting there and I got permission to use them on my own free time. So I took advantage of the opportunity and made it while I had the chance.

3: Ah, you ran across my project within a project. I am not going to tell much about this one because I might want to pursue this later. Lets just say it is an idea that a friend and I have had for a while and people have failed shooting these things in the past. Now with my new platform, the small ones that were tried in the past can now be scaled up and tried again. What I will say is this thing is approx 500 Grains and I am hoping to have it go between 4000-5200 fps. We will see.

Happy Holidays.

 

[0311 Hesco]

Ok,
Standard disclaimer applies, ( I don't really know a whole lot, blah blah, blah). What if you were to hollow out one of these turned bullets and then fill it with molten lead? I know the process would be really long and drawn out, but you would get the perfect concentricity from being turned on a lathe or CNC, then have the weight of the lead. You wouldn't even have to bore all the way out either. Just enough where you can achieve a balanced projectile. Right?
Feel free to blast me if I'm just being retarded.

 

[Noel Carlson]

kd185

I know for a fact that a 900 grain copper 50 BMG projectile can be made to stabilize from a 1:15" twist at Raton during summer (in high humidity). A 1:13" is really required for general use however, and a better projectile weight given available propellants is approximately 840 grains. Brass does not have the specific gravity necessary to achieve gyroscopic stability (and lead is too dense to provide the volume required for a good form factor).

If you need a match barrel tighter than 1:15", PM me.

 

[kd185]

kd185

I know for a fact that a 900 grain copper 50 BMG projectile can be made to stabilize from a 1:15" twist at Raton during summer (in high humidity). A 1:13" is really required for general use however, and a better projectile weight given available propellants is approximately 840 grains. Brass does not have the specific gravity necessary to achieve gyroscopic stability (and lead is too dense to provide the volume required for a good form factor).

If you need a match barrel tighter than 1:15", PM me.

pm sent

 

[Dylanss180]

Formed some cases last night. Also loaded a scrap bullet I made.
The forming die I made works awesome


On the picture below the case on the left is a .308 the Middle is a .50bmg and my new one on the right.

 

[ahhshoot]

Admittedly this stuff is way beyond my knowledge of projectiles, and please forgive me for going a little off topic here, I just see the knowledge that is in this thread and thought you guys might be the right ones to ask. This is purely a thought that has no purpose whatsoever and it may be a stupid question, but I have often wondered if anyone has ever tried to produce a 'football' shaped bullet.

Being that a football seems extremely stable with regards to velocity and rotation... and it's being chucked from an arm, let alone a precision rifle built on exacting tolerances.

The gas seal thing seems like it would be solved by the driving bands. Obviously copying a football wouldn't work, there would need to be a portion of ogive in the center. It seems like it could be stable and have a very slippery BC.

I realize I'm not the first to think of this, but can anyone here explain why it hasn't worked before?