Modern Sporting Rifle Evolution
Register Calendar Latest Topics Chat
 
 
 


Reply
  Author   Comment  
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #1 

Good Day All.

I have been digging to find a wildcat around the 40mm OAL (Carbine/PDW size) with good performance and have come up with nothing but undersized - underpowered - inefficient cartridges. 

As a result: I designed one myself.

Let me introduce you to the 7mm Leviathan Carbine.

7mm Leviathan Carbine.png
(Source Program: QuickDESIGN - QuickLOAD) Performance out of a 12inch Barrel
This Cartridge uses a Speer 28 CAL (.284) 130 GR BTSP with a G1 BC of ~ .424
What that means is greater reach with the Carbine/PDW setup - In Concept: Lethal out to 500yards.

7mm Leviathan Ballistics.png 
(Source: https://www.hornady.com/team-hornady/ballistic-calculators/#!/ )

This is a concept - and I would very much like an open source collaborative approach to feedback - criticism - and partners in development. 

 

 
Attached Files
pdf 7 mm Leviathan.pdf (1.07 MB, 15 views)


__________________
Seek Wisdom and Knowledge shall follow.

0
crazysccrmd

Avatar / Picture

MSR Enthusiast
Registered:
Posts: 329
Reply with quote  #2 
I'm not sure I see the purpose of the round in a practical sense. A claimed lethality of 500yds is pretty ridiculous in my opinion when it comes with 161" drop.

0
battle rattle

MSR Enthusiast
Registered:
Posts: 149
Reply with quote  #3 
as a PDW the 100 yd zero sounds right for a red dot sight / dead on hold, should do a little better out of a pedestrian legal length 16" tube 

reminds me of the JAWS cartridge family, 5.56/223 rim & base dimensions?

FWIW i'd spec a round nose / soft point flat base bullet, no need for the BT & the FB does better in this role, unfortunately not much to choose from in the 7mm diameter 

Hornady has a monolithic 139gr GMX and Lehigh defense has a progressive fragmentation 125gr Controlled Chaos (both Boat Tail) 

https://www.lehighdefense.com/collections/bullets/products/284-125gr-controlled-chaos-high-velocity-lead-free-bullet?variant=1073856924
0
BIGGDAWG

Avatar / Picture

Moderator
Registered:
Posts: 2,377
Reply with quote  #4 
using rifle bullets i can say that with my gel testing they will not expand below 1600-1800 fps just so you know.

i did distance gel testing for the valkyrie you can look up the videos on youtube.  not that they won't kill but if youthink they are leathal at 500 yards i personally wouldn't even think of taking a shot that long with it only moving 1100 fps with 161 inches of drop.

__________________
http://www.7mmvalkyrie.com




0
BIGGDAWG

Avatar / Picture

Moderator
Registered:
Posts: 2,377
Reply with quote  #5 
using rifle bullets i can say that with my gel testing they will not expand below 1600-1800 fps just so you know.

i did distance gel testing for the valkyrie you can look up the videos on youtube.  not that they won't kill but if youthink they are leathal at 500 yards i personally wouldn't even think of taking a shot that long with it only moving 1100 fps with 161 inches of drop.

__________________
http://www.7mmvalkyrie.com




0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #6 

Quote:
Originally Posted by crazysccrmd
I'm not sure I see the purpose of the round in a practical sense. A claimed lethality of 500yds is pretty ridiculous in my opinion when it comes with 161" drop.

Appreciate the feedback.

I believe my theory to hold true the same way I believe 300 AAC Blackout to be capable of lethal effects at 600yds with near the same metrics.

300 AAC Blackout 600YD.png 

Ammo simulated above listed below.

https://www.midwayusa.com/product/1001921122/nosler-match-grade-ammunition-300-aac-blackout-125-grain-ballistic-tip-box-of-20

Here is the metrics Travis Haley puts on the 300BLK.

"Travis talks about HSP's year in 300 Blk Out. He also takes to opportunity to discuss their findings and explain their justification of the round as a multi purpose platform in both short and long range situations."

As well as some forum commentary:

"The US Military rates the Max Effective Range of the M4 as 500 meters for a point target.

If the max effective range of the M4 with M855 at 2900 fps is 500 meters, that has 100 inches of drop, 41 inches drift, and 291 ft/lbs of energy:

16 inch 300 AAC BLACKOUT 125 grain at 2220 fps has:
100 inches drop at 440 meters
41 inches drift at 484 meters
291 ft/lbs of energy at 700 meters.

The military tends to go by hit probability rather than energy. If we use the drift and drop range as being correlated with hit probability, and discount the energy advantage of 300 BLK, we get 462 meters.

Using M4 military hit-probability standards, the max effective range of 300 AAC Blackout from a 16 inch barrel is 460 meters."

*Stolen from this thread http://www.300blktalk.com/forum/viewtopic.php?t=78108 *

I think this lays out the list of "limitations" we set upon ourselves. Up front I don't believe Max Effective Range is a useful metric to judge "lethality" as one shot doesn't hit - allow the trigger to reset and adjust fire until the threat is gone.

If the limit of Max Effective Range for this cartridge is 400yards or so I'd still take it as a good performer for its form factor.

Now that item is a dead horse - whether you see my perspective or still disagree, I didn't state the other half of the story.

The idea with this round is to have a carbine/pdw which is interchangeable with a sidearm chambered in the same round, but with punch. 

Similar to the concept of the 7.5FK - but with the extra 5mm to gain the extra BC to push it a bit farther.

7.5 FK

https://www.americanrifleman.org/articles/2016/5/2/the-world-s-fastest-pistol-75-fk-brno/

The space savings on the kit - and the shorter OAL will do well for keeping weight down, without having to cut engagements of personal defense within 300yds. (As with any other PCC setup) 

Clear as mud? I hope that lays the idea out a bit more.

Always happy to extrapolate the concept to see flaws.



__________________
Seek Wisdom and Knowledge shall follow.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #7 

Quote:
Originally Posted by BIGGDAWG
using rifle bullets i can say that with my gel testing they will not expand below 1600-1800 fps just so you know.

i did distance gel testing for the valkyrie you can look up the videos on youtube.  not that they won't kill but if youthink they are leathal at 500 yards i personally wouldn't even think of taking a shot that long with it only moving 1100 fps with 161 inches of drop.

Good feedback! My concept of use has it hitting hard enough at 500 yards to deter the enemy not necessarily a Mike Tyson punch but to reach out with enough force to engage at a further distance instead of be limited to sub 300 yard duals.


__________________
Seek Wisdom and Knowledge shall follow.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #8 

Quote:
Originally Posted by battle rattle
as a PDW the 100 yd zero sounds right for a red dot sight / dead on hold, should do a little better out of a pedestrian legal length 16" tube 

reminds me of the JAWS cartridge family, 5.56/223 rim & base dimensions?

FWIW i'd spec a round nose / soft point flat base bullet, no need for the BT & the FB does better in this role, unfortunately not much to choose from in the 7mm diameter 

Hornady has a monolithic 139gr GMX and Lehigh defense has a progressive fragmentation 125gr Controlled Chaos (both Boat Tail) 

https://www.lehighdefense.com/collections/bullets/products/284-125gr-controlled-chaos-high-velocity-lead-free-bullet?variant=1073856924

The biggest battle we face with the bullet selection is length. The bullet takes up 2/3 of the OAL of the cartridge. The SPEER .284 130 GR BTSP is only 1.060 inches in length with a .424 G1 BC the most efficent for its size outside custom turned creations.

The parent case is a 6.8 SPC ii - so quite a bit larger than the 5.56 case dimensions circumference wise - but similar concept.

Here is the 16inch metrics per the computer models.

7mm Leviathan Carbine 16inch.png 

7mm 130 16 ball.png 



__________________
Seek Wisdom and Knowledge shall follow.
0
crazysccrmd

Avatar / Picture

MSR Enthusiast
Registered:
Posts: 329
Reply with quote  #9 
The military's definition of max effective range is the capability to put 50% of rounds on target at that distance and has no bearing on lethality.

Given the length of the cartridge would the accompanying handgun have to be designed with the magazine separate from the handgrip or be similar in grip size to a desert eagle?

If you went with a more traditional pistol wildcat like the 9x25 Dillon you'd have very similar velocities with the same weight of bullet, better bullet selection in terms of expansion potential and an easier time finding a handgun able to be chambered in the same round. Max effective range would suffer with the less aerodynamic pistol bullets but wouldn't make a real world difference in trajectory until beyond 300 yards.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #10 
Quote:
Originally Posted by crazysccrmd
The military's definition of max effective range is the capability to put 50% of rounds on target at that distance and has no bearing on lethality.

Given the length of the cartridge would the accompanying handgun have to be designed with the magazine separate from the handgrip or be similar in grip size to a desert eagle?

If you went with a more traditional pistol wildcat like the 9x25 Dillon you'd have very similar velocities with the same weight of bullet, better bullet selection in terms of expansion potential and an easier time finding a handgun able to be chambered in the same round. Max effective range would suffer with the less aerodynamic pistol bullets but wouldn't make a real world difference in trajectory until beyond 300 yards.


I'd really enjoy a 9x25 Dillon PCC - unfortunately the only ones I have found are Frankensteins.

I'd liken the handgun to be more of the FN 5.7x28 and finding a way to maximize the magwell use for longer OAL and remove the space taken by the mainspring housing. This is an engineering problem that will take some effort.

I'll have to see what terminal ballistics turns out to be after the round goes down the pipe and into some ballistics gel and bone simulant at various ranges to test the viability of longer range engagements. 'Tis the only way to know for sure.

I'd really like for it to be reaching out efficently - but I am at the crux of any longer it won't meet the handgun role; any shorter it won't have the power to matter at distance when tweaking the OAL.

I ran the numbers on the other projectiles 100gr-120gr none of them catch up to the BC advantage of the Speer 130 GR BTSP. The energy retention alone I think will do great things for a PDW of this form factor. ~500 ft/lbs at 300 yards compared to the ~250ft/lbs the 9x25 could put out would be all the difference I need to meet my philosophy of use between the two.

Don't get me wrong, I'll buy both PDW's - only if I had to choose.

__________________
Seek Wisdom and Knowledge shall follow.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #11 

I have also been exploring the Subsonic capabilities this cartridge may possess. In this search, the twist rate would need to change to a 1 in 8.25 RH Twist from the previous 1 in 10 RH Twist.
Here are the specs.

7mm Leviathan Subsonic.png 
This is a custom .284 176gr RNBT
Subsonic perform.png 
(Source Program: QuickDESIGN - QuickLOAD) Performance out of a 12inch Barrel
Subsonic Ballistics.png 
(Source: https://www.hornady.com/team-hornady/ballistic-calculators/#!/ )


As always - don't hold back - let me know what you think.

Appriciate the feedback!



__________________
Seek Wisdom and Knowledge shall follow.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #12 

I had to run the numbers again because the seating depth was throwing me off for the 80 gr projectile.

Here is a lightweight load of the 7mm Leviathan.

7mm 55gr model.png 
(Source Program: QuickDESIGN - QuickLOAD) Performance out of a 12inch Barrel

7mm light.png 
(Source: https://www.hornady.com/team-hornady/ballistic-calculators/#!/ )

7mm 80gr 5 inch.png 

(Source Program: QuickDESIGN - QuickLOAD) Performance out of a 5inch Barrel (13.7gr load)

5inch ball.png 

(Source: https://www.hornady.com/team-hornady/ballistic-calculators/#!/ )



__________________
Seek Wisdom and Knowledge shall follow.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #13 
Doing some more research into my wildcat, I ran across the original "intermediate" cartridge, the 7.92x33 Kurz
 
The similarities with the form factor and chamber pressures are fascinating.
 
This article goes into the Frankin-guns the Pakistani's are using which will chamber both the 7.92x33 and the 7.62x39.

http:// http://armamentresearch.com/44-bore-7-62-x-39-mm-ak-rifles-modified-to-fire-7-92-x-33-kurz-ammunition/

256fbld.jpg 

7.92x33 Kurz Max Pressure: 340.00 MPa (49,313 psi)
 
 


__________________
Seek Wisdom and Knowledge shall follow.
0
Carl S.

Senior Member
Registered:
Posts: 72
Reply with quote  #14 
have been intrigued with your postings regarding the Leviathan.  You may want to check out the .338 Spectre...attached are a couple of photos, one has the PPU Kurz 124 gr FMJ alongside an SBR .338 Spectre 225 gr JSP.  The other photo has the Kurz in the Spectre case gage.  I am not much of a photographer and those are cell phone shots.
Remove Formatting
P82A03671.jpg  P82A03681.jpg 

0
Carl S.

Senior Member
Registered:
Posts: 72
Reply with quote  #15 
Here is a side by side Kurz on the left and Spectre on the right.
P82A03691.jpg

0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #16 
Quote:
Originally Posted by Carl S.
have been intrigued with your postings regarding the Leviathan.  You may want to check out the .338 Spectre...attached are a couple of photos, one has the PPU Kurz 124 gr FMJ alongside an SBR .338 Spectre 225 gr JSP.  The other photo has the Kurz in the Spectre case gage.  I am not much of a photographer and those are cell phone shots.


Thanks, Carl! I'd be very interested in learning more about the .338 Spectre. I found a few pockets of information here and there a few years back when I was starting my journey with the 7.62x40WT, but since then haven't found much on the development.

Do you have any links to the bulk of information, or by the looks of it - your experience with the .338 Spectre that may translate?

__________________
Seek Wisdom and Knowledge shall follow.
0
Carl S.

Senior Member
Registered:
Posts: 72
Reply with quote  #17 
YETIPRODUCTIONS, I added a thread over in Medium Bore AR-15 cartridges regarding most of what I have found that is substantial about the Spectre.  I see there has been some mention of it in this MSRE forum.  Nice chatting with you. 
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #18 
I've edited the neck length to move from the original 3mm to a new 5mm dimension. This is the same dimension as the 5.56 NATO.

7mm Leviathan Carbine 5mm NECK.png

Please let me know if y'all have any additional thoughts on the project.




__________________
Seek Wisdom and Knowledge shall follow.
0
Yetiproductions

Avatar / Picture

Senior Member
Registered:
Posts: 63
Reply with quote  #19 
Here is the new perfornance projections. BLUF - lose 50 FPS in exchange for ~1.8mm longer neck area.
7mm Leviathan Carbine 5mm SPEC.png 


__________________
Seek Wisdom and Knowledge shall follow.
0
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.