Design the Rifle around the cartridge, Cartridge to the job,,excerise

[Float Pilot]

Ok there are more than a few experimental cartridges and rifles which never came to full production.

In the old days a cartridge was often developed first and then the firearm was made to fit it.....

Here is the exercise:

1. Propose a cartridge for general infantry use. It must:

A. Have a projectile of 6mm or larger.

B. Have an effective combat range of 300 meters making torso hits from 50 to 300 meters without sight adjustments. (limited bullet drop)

C. Be capable of producing extensive trauma with torso hits

2. Propose a rifle design for general infantry use which:

A. Weighs 8 pounds or less.

B. Can use optical or iron sights, without total removal of the iron sights.

C. Is resistant to stoppage caused by dirt and dust.

D. Can be immersed in water and safely fired within five seconds of retrieval.

E. Contains the minimum number of parts needed. (soldier proofing).

Explain the rational for proposed examples.

Feel free to bring up cartridges like the 6x45mm SAW, the 6.35x48mm, 280/300 British Experimental and so on....

 

[R.W.Dale]

a flattop piston AR in one of the 6.x cartridges o the day?


Thread over

 

[blackwell bikes]

any 6.5 in a Mauser action i like 6.5-06, with right stock its under 8pds, either a side mounted scope or high rings let you use irons,C- the only thing that will stop that Mauser is you dieing......... soaking it in water for 5 seconds sounds like a cleaning.

but seriously a 6.5 grendel or 6.8spc?. then build a piston-driven rifle much like a 416(<- boring) or a lwrc m6a1/a2 I think the rec7 shows promise around it and enter it in trials.

 

[Casefull]

I am with krochus but would want to make the bullet at least 7mm but keep the case small as possible for mag capacity. I would want at least 125g at 3,000 fps.

 

[MachIVshooter]

Almost every battle rifle of the 20th century meets those criteria.

 

[Andrew Wyatt]

okay, done. now what?

 

[Slamfire]

Hey at least you are getting the idea of a requirements document.

In real weapon system development the requirement documents start out simple, but a lot more detailed than what you wrote, and as the system matures, go to 100's of pages.

Lots of money is conducted testing lethality of the round against different mediums, analysis of issues such as practical accuracy at various distances. Compatibility of propellant, cases, materials. And can the thing be built with today's technology.

There will be troop trials, soldier feedback, design iterations. Lots of fights between the developer and user as to environments and testing. The user wants to break the system, the developer wants the system wrapped in bubble wrap so it won’t get hurt.

 

[Float Pilot]

Almost every battle rifle of the 20th century meets those criteria.

Exactly... But folks want to talk all about long range engagements, even though most troops can't hit anything past 200 much less 300 meters.

But what the heck, let us change a couple things::

1. The projectiles trajectory must be within 16 inches of the muzzle line at 500 YARDS. With a 500 Yard zero.

2. The magazine capacity must be at least 20 rounds.

3. The weapon must be capable of semi-automatic fire.

4. And we can now consider calibers as small as 5.56mm (223)

People tend to think inside the box,, even in mental masturbation exercises such as this (I'm waiting for better flying weather)...

So we tend to think of either an AR platform or an AK type.

Then we think 5.56mm length action (6.8x43 and 6.5 Grendel inclusive) or a 7.62mm Nato length platform ...

Why not something in between?
Why not something with a wider magazine box to accommodate a larger diameter casing... ???

A 7.62mm NATO ball round has a flight path that is 22.7 inches high when zeroed at 500 yards. So it does not meet the magical criteria.

BUT.. a 6mm (.243) 95 grain boat-tail bullet at 3,200 fps muzzle velocity is only 14.2 inches above the bore line at it's maximum height when zeroed at 500 yards.

In fact, according to my ballistics calculator a 77 grain 223 caliber Sierra OTM bullet at 3,200 fps muzzle velocity is only 16 inches above the bore line at its maximum when zeroed for 500 yards.

Of course a 5.56mm NATO case does not have enough case capacity to drive a 77 grain OTM to 3200 fps.
Nor does a 243 Win Case have enough room to drive a 95 grain VLD to 3,200 fps,,, unless it has a longer barrel....

But a 223 WSSM will do it and a 243 WSSM will too....

HMMM,,, they are a little stubby to work in a semi-auto action ,,, at least reliably..
....Makes you wonder,,, maybe trade off some diameter for length ???

Worrying about if it would fit a current rifle is wasting time... everybody thought semi-auto pistol's had to have certain parts until toy maker Gaston Glock made his first pistol based upon what he thought it needed to work...

 

[USSR]

BUT.. a 6mm (.243) 95 grain boat-tail bullet at 3,200 fps muzzle velocity is only 14.2 inches above the bore line at it's maximum height when zeroed at 500 yards.

In fact, according to my ballistics calculator a 77 grain 223 caliber Sierra OTM bullet at 3,200 fps muzzle velocity is only 16 inches above the bore line at its maximum when zeroed for 500 yards.

You'll burn your throats out in no time. Logistics is part and parcel with the adoption of anything new for the armed forces. It really isn't all that hard to teach recruits the trajectory of their load.

Don

 

[Slamfire]

But what the heck, let us change a couple things::

1. The projectiles trajectory must be within 16 inches of the muzzle line at 500 YARDS. With a 500 Yard zero.

2. The magazine capacity must be at least 20 rounds.

3. The weapon must be capable of semi-automatic fire.

4. And we can now consider calibers as small as 5.56mm (223)

After spending $200 Million of your pocket money, tell us how the rifle turns out.

Make that $400 Million.

 

[Uncle Mike]

It has already been done....the 6.5 Grendel by Bill Alexander of Alexander Arms and Arne Brennan.

 

[Float Pilot]

You'll burn your throats out in no time.

Like the original 3,200 fps 5.56mm rounds from an original M-16....?? 3,200 fps for a 77 grain ?? maybe,

Make that $400 Million.

Yeap sure would... Maybe more.... but most of the folks here are so opinionated about infantry rifles, that we can pay in Monopoly Money for this exercise. That is about what our real money will be worth after the yahoos in Washington finish with us...

It has already been done....the 6.5 Grendel by Bill Alexander of Alexander Arms and Arne Brennan.

Nope, the Grendel does not stay within 16 inches of bore-line with a 500 yard zero.
realistically the Grendel will push a 120 gran boat-tail along at 2,550 to 2,600 from a 18 to 20 inch barrel. And around 2,850 for a 95 grain bullet which has a not-so-good BC.
A 120 Sierra SMK at 2,600 fps muzzle velocity goes 23 inches high when zeroed at 500 yards.

 

[R.W.Dale]

With today's ballistic compensating optics IMO the trajectory stipulation is pointless

 

[Float Pilot]

Really the whole thing is pointless, but it is blowing too hard for any good float-plane flying....

Although, a 6mm, 95 grain SMK at 3,200 would give you a big ouchy....

 

[R.W.Dale]

Although, a 6mm, 95 grain SMK at 3,200 would give you a big ouchy....

I'm sure it would

But to put things in perspective as to the case needed to hit those speeds 6mm rem or 6x57 only advertises 3100 and 240wby gets 3400fps in what I'm sure is a 26" tube

 

[wlewisiii]

175gr 7x57 in an 1893 Mauser will suffice. Make it a 98 action if you wish but even the 93 will meet all of the OP's requirements.

William

 

[Zak Smith]

Get back to us how well a 500-yard zero works for practical shooting. Hint: it's great if you want to miss everything high from approx 50 to 450 yards.

 

[Float Pilot]

Get back to us how well a 500-yard zero works for practical shooting

Yeap I agree that's why I said this

Exactly... But folks want to talk all about long range engagements, even though most troops can't hit anything past 200 much less 300 meters.

It was a trajectory remark about being within 16 inches... Which in itself was a number I pulled out of my hind end while measuring from my belt to my upper sternum...

Zak,, if you have not noticed I am poking fun at some other threads...

Krocus is right.. the 243 Win, 6mm rem (aka 244 rem) 6 x47 Lapua and 243 Ackely Improved
And most of the others can't reach 3200 fps MV with a 95 grain bullet (has a good BC of 486 with a Berger VLD.
Except this guy with a 22 inch M-700. Which I wonder if he really meant 24 inch...?
Bullet Nosler Partition
BulletWeight 95 grs
Powder Alliant Reloader 22
PowderWeight 49 grs
Primer CCI BR2
Brass Make Remington
Barrel Length 22 (inches)
C.O.L (inches)
Velocity 3275 fps
Group 0.482 (inches by 3 shot at 100 yds)

Even the 243 WSSM will barely do it with a 24 inch barrel
Of course then there is the huge 6mm-284
http://www.reloadersnest.com/frontpage.asp?CaliberID=103 It works.....

and the even larger 6mm-264Win also known as the 6mm or 240 Incinerator.
http://www.reloadersnest.com/frontpage.asp?CaliberID=320
That baby really screams. I'll bet barrel life is super limited...


So other than maybe a bull-pup 243WSSM or maybe 257 WSSM with a 24 inch barrel it ain't gonna happen... And even then it is not worth it...

 

[Jim Watson]

My prediction is the regulars will keep the M16 and M4. The Marines are getting softpoint - OK, "open point" - bullets under the guise of "improving accuracy" in the M4. What can a wog do to you for shooting at him with a softpoint that he wouldn't do anyhow?

The elite units will likely get small purchases of whatever action and caliber seems useful at the time.

There will not be a general move to reequip until something really kewl comes along. They have been predicting caseless ammo for a long time now, maybe it will get that last push. Or telescoped plastic cases.

 

[R.W.Dale]

This thread got me thinking about another possibility

What if we focused on increased lethality through more bullet and caliber. Take my 30ppc largo wildcat. Use a 125g bullet with a bc of around .370 at a mv of 2600

now this is no means spetacular sure. But the interesting bit is if you do the throat right you'd be able to shoot the enemy's ammo in a pinch but they wouldn't be able to shoot ours.

 

[Zak Smith]

Hey, it's your criteria.

The cost for additional maximum point blank distance increases exponentially and that's not how long-range shooting is done anyway.

When 5th SFG worked on the 6.8 SPC one of the design goals was pointedly not better trajectory than Mk262, though it was intended for use in the SPR (out to those distances). Thus, one might conclude that Mk262's trajectory isn't a big problem for mid-range (ie 500m) engagements for the intended audience.

 

[M1key]

I would think the "enemy" is more likely to be shooting 5.45 or 5.8......

 

[MachIVshooter]

But to put things in perspective as to the case needed to hit those speeds 6mm rem or 6x57 only advertises 3100 and 240wby gets 3400fps in what I'm sure is a 26" tube

The 6mm Rem will do it. I get 3,310 FPS with 90 gr. FMJ's over 47.3 grs. H4350 from a 22" Ruger M77. That's my coyote load.

But......

The 6mm Rem., based on the 7mm Mauser case (actually, the .257 Roberts, which in turn was based on the 7x57, but that's nitpicking) would need an even longer action than the 7.62 NATO.

 

[Float Pilot]

The 6mm Rem will do it. I get 3,310 FPS with 90 gr. FMJ's over 47.3 grs. H4350 from a 22" Ruger M77. That's my coyote load.

But......

The 6mm Rem., based on the 7mm Mauser case (actually, the .257 Roberts, which in turn was based on the 7x57, but that's nitpicking) would need an even longer action than the 7.62 NATO.

Hmmm, a modified FN-49 with a box mag.....

 

[Al Thompson]

One other thing to throw in the thought process... Why not use some uber-lightweight material for the rifle?

A titanium Galil in 6.8 with a rail for optics would be an interesting rifle.

So, max weight for a loaded rifle w/optic = ~ 8 lbs. ?