Main Military Weapon of Your Country (Mk. IV) The Proper Un

[Ularn]

The bullet will indeed be capable of travelling that far, if the rifle is angled up far enough. Thing is, ignoring air resistance, max range occurs at 45degrees elevation, & I've seen claims that 5.56N will get to 2000m+ in that scenario. So 800m with more moderate elevation is certainly physically possible, and I suppose in ideal atmospheric conditions you might still hit the target if the rifle were held very stably.
Of course, whether being able to hit a target at 800m with an M4 leaves enough energy in the round to do anything useful is a whole other question.

M855A1 apparently is capable of penetrating a kevlar vest at 1000m.

That makes sense. Assuming that the forward speed of a bullet remains constant throughout its flight (which is true, ignoring the air resistance which I assume (possibly incorrectly) is negligible), a bullet fired in an arc will actually be travelling faster than when it left the barrel as it is now travelling forwards at the same speed it left the gun at plus the additional downward speed it has gained from being pulled by gravity.

So assuming you're unfortunate enough to be hit by a bullet fired at a 45^o arc, I imagine it would actually hit you harder than one fired directly.

[EDIT]: This is assuming that I'm right that the effect of air resistance on a bullet is more or less negligible, a point on which I may be mistaken, but unless the deceleration in causes the bullet is equal to or greater than 9.8m/s², a bullet will have a higher overall speed by the time it hits the target as the firing arc approaches 45^o.

Then again, I'm making no comment about how such practice might screw with your terminal ballistics.

[Celtic Colonies]

M855A1 apparently is capable of penetrating a kevlar vest at 1000m.

That makes sense. Assuming that the forward speed of a bullet remains constant throughout its flight (which is true, ignoring the air resistance which I assume (possibly incorrectly) is negligible), a bullet fired in an arc will actually be travelling faster than when it left the barrel as it is now travelling forwards at the same speed it left the gun at plus the additional downward speed it has gained from being pulled by gravity.

So assuming you're unfortunate enough to be hit by a bullet fired at a 45^o arc, I imagine it would actually hit you harder than one fired directly.

Nope, the bullet can't have more energy than it started with. The extra speed added by gravity on the way down only counteracts the loss of speed on the way up, but it doesn't add to the total energy of the system. In reality, losses from air resistance might be small, but they'll be enough to ensure there's a little less energy in the round at the end of the flightpath than at the start.

[Immoren]

M855A1 apparently is capable of penetrating a kevlar vest at 1000m.

That makes sense. Assuming that the forward speed of a bullet remains constant throughout its flight (which is true, ignoring the air resistance which I assume (possibly incorrectly) is negligible), a bullet fired in an arc will actually be travelling faster than when it left the barrel as it is now travelling forwards at the same speed it left the gun at plus the additional downward speed it has gained from being pulled by gravity.

So assuming you're unfortunate enough to be hit by a bullet fired at a 45^o arc, I imagine it would actually hit you harder than one fired directly.

[EDIT]: This is assuming that I'm right that the effect of air resistance on a bullet is more or less negligible, a point on which I may be mistaken, but unless the deceleration in causes the bullet is equal to or greater than 9.8m/s², a bullet will have a higher overall speed by the time it hits the target as the firing arc approaches 45^o.

Then again, I'm making no comment about how such practice might screw with your terminal ballistics.

I think you are forgetting conservation of energy and momentum?

[Samozaryadnyastan]

For some rifle bullets, the deceleration due to air resistance can be as much as 1700fps (~520m/s) per second of flight time. It's so significant, one ballistics expert once commented on how it was more sensible to ignore the effect of gravity (a mere 9.8m/s^2) than that of air resistance.

[Ularn]

I think you are forgetting conservation of energy and momentum?

Nope. The extra energy was being imparted by the outside force of gravity acting on the bullet. What I had forgotten about was this:

Nope, the bullet can't have more energy than it started with. The extra speed added by gravity on the way down only counteracts the loss of speed on the way up, but it doesn't add to the total energy of the system. In reality, losses from air resistance might be small, but they'll be enough to ensure there's a little less energy in the round at the end of the flightpath than at the start.

So in fact everything I said would only apply if you fired a gun from an elevated position in relation to your target, e.g. from on top of a cliff, and I'm still speaking in hypothetical since I'm only recalling my High School Physics lessons and doubt any of what I'm saying could ever be practically applied in a battlefield situation. The odds of you being able to hit a target at the sort of ranges where this stuff to come into play are so insignificant as to render the whole exercise moot.

Also, according to Para I have vastly underestimated the importance of air resistance on a bullet.

[Mosasauria]

For some rifle bullets, the deceleration due to air resistance can be as much as 1700fps (~520m/s) per second of flight time. It's so significant, one ballistics expert once commented on how it was more sensible to ignore the effect of gravity (a mere 9.8m/s^2) than that of air resistance.

So, in other words, this guy was bullshitting me.
It can hit a target at that range, but probably not easily, and probably not lethally due to the wide variety of conditions and effects. Got it.

[Samozaryadnyastan]

It's somewhere within this glorious, yet depressing document.
I say depressing, because it debunks absolutely ever fact I thought I knew about terminal ballistics. And that 7.62x39 is actually a good round against infantry (in wounding potential, exactly what I used to slam it for), and how fragmentation and yawing not only are similar in effect, but that the effect is actually minimal and not particularly contributing to lethality (but possibly to 'stopping power').

The quote in question:

Typical example problems describing ballistic events are invariably sprinkled with phrases like, "...neglecting air resistance...", "...assuming perfectly elastic (or rigid) bodies...", and "...a collison between perfectly plastic bodies...". Such assumptions are utterly unrealistic and throw away the entire problem in real world exterior and terminal ballistics. One could more sensibly neglect gravity than air resistance! The acceleration due to gravity is only 32.174 ft/s2, but the (negative) acceleration due to air resistance is on the order of 1700 ft/s2 or more for high velocity rifle bullets. The equations of motion governing ballistic flight of projectiles are a set of highly complex, coupled second order differential equations that have no analytical solution, so the textbook manufacturers don't want to discuss it. Its easier to give the student a false impression of reality with a problem that is simply solved.

[Crookfur]

On the M4 vs the L85A2, they are both good systems with thier own pros and cons.

Biggest plus for the M4 is ergonomics. Nothing beats Stoner's original M16 layout bar those rifles that use it as a starting point for a few mods of thier own (i.e. the various ambidextrous and charging handle mods). In terms of speed of reload, balance, weight and ease of use the M4 pretty much beats the L85A2 handily which is why the vast majority of "special people" in western militaries use some kind of M4/CAR-15 based rifle and why all the various tactical carbine "artists" use it.

Does this make it overall a better gun? That simply depends on how you weight the various factors in your decision making as for range, debatably accuracy), relaibility and of coruse britishness (which does of carry a >9000 weighting) the L85A2 comes out top.

There is no right answer there is simply what you like and what you feel fits.


Yellow Zone 20-A:

Sounds like you want the Crookfur Arms total 6.25mm caseless solution!

Start with fabby SX23A2 rifle

Move onto the SX25 LSW or SX24 LMG

Then the SX30 DMR or possibly a scout rifle version of the Wallace Elder No.123 (notstated yet), heck you can even have it integrally supressed. Actually those later two are very much WIP i had forgotten how rough they were, both need MOAR scout rifle.

Finally for cheapy cheaps there is the Wallace Elder No.138.


Or if you want Rl you can use versions of the FAL, M16/AR-15/M4geries, G3 and G36 (plus others) for all of the above roles.

[The ACF]

Updated weapons list.

Handguns / Machine Pistols
- FN Five-seveN
- Colt 6520 10mm Pistol
- Modernized variants of the colt M1911A1
- H&K USP
- Various types of glock
- Beretta M9

SMG's / PDW's
- H&K MP7A1
- FN P90TR
- TDI Vector

Shotguns
- Kel-tec KSG
- SRM 1216 Rotary Shotgun

Assault Rifles
- Bullpup bushmaster ACR (and the non-bullpup original version)
- H&K G11E

Battle / Designated Marksman Rifles
- M14 variants (Mostly bullpup)
- Kel-Tec RFB

Light Machine Guns
- The LMG variant of the G11,whatever it was called.

Grenade Launchers
- XM25 CDTE
- Mk.19 Grenade launcher

Medium / General purpose machine guns
- M60E4

Rocket / Missile Launchers
- M72 LAW
- FGM-148 Javelin

Heavy machine guns
- Browning M2HB

Sniper / Anti-Material rifles
- Gepard GM6 'Lynx'
- Accuracy International AS50

[Krumbia]

FGR Standard Rifle Mk III
https://dl.dropbox.com/u/8705132/Lineart/FGR/FGR%20Finished.png

Made by Questers. Now an ex-nation. Find more info here.

[Imperial isa]

Questers a ex nation again huh

[Novo Casttria]

Cheymograd Arsenal is open for business!

[Krumbia]

Questers a ex nation again huh

So it seems.

[Consaria]

Why do bolts have to be locked into the receiver in modern rifles? And why do delayed blowback rifles often have a different locking system than rotating bolt?

[Celtic Colonies]

Why do bolts have to be locked into the receiver in modern rifles? And why do delayed blowback rifles often have a different locking system than rotating bolt?

Couple of minor quibbles first:
1: It's not just modern rifles, pretty much ever since the earliest breech loading rifles locked breeches have been the norm. I'm sure there are a few exceptions, but not many.
2: Technically, delayed blowback systems aren't actually locked at all, as the bolt is moved rearward directly by the pressure of the fired case. The delaying mechanism only serves to slow that down to give a safe interval between firing and opening the chamber.

Anyhoo, on to actual answers...

A bolt that is not locked is held in place only by the inertia of its own mass and the force of the return spring, known as (simple) blowback operation.
That's fine for lower powered stuff like some SMG's but as soon as you get to more powerful rounds the mass and spring stiffness you need to keep the bolt shut long enough for the bullet to leave the muzzle are just too great to be practical. (You don't want the bolt to extract the case before the bullet has left the muzzle as there would be too much high pressure gas venting back into the receiver - not good.)
So for higher powered rounds, you either lock the bolt in place eg by rotating it so lugs engage with recesses in the receiver, or you add a mechanism to delay the blowback operation long enough to have the chamber pressure reduced to a safe level before the chamber is opened, without resorting to stupidly heavy bolts with really stiff springs.

Delayed blowback systems have to use different mechanisms for "locking" because they get the impetus for their operation from a different place & direction. A locked, rotating bolt has to be rotated first, before it can move backwards, but in delayed blowback the first (and only) movement that drives they system is directly backwards, so there isn't any opportunity to effect rotation first.

[Crookfur]

Why do bolts have to be locked into the receiver in modern rifles? And why do delayed blowback rifles often have a different locking system than rotating bolt?

Couple of minor quibbles first:
1: It's not just modern rifles, pretty much ever since the earliest breech loading rifles locked breeches have been the norm. I'm sure there are a few exceptions, but not many.
2: Technically, delayed blowback systems aren't actually locked at all, as the bolt is moved rearward directly by the pressure of the fired case. The delaying mechanism only serves to slow that down to give a safe interval between firing and opening the chamber.

Anyhoo, on to actual answers...

A bolt that is not locked is held in place only by the inertia of its own mass and the force of the return spring, known as (simple) blowback operation.
That's fine for lower powered stuff like some SMG's but as soon as you get to more powerful rounds the mass and spring stiffness you need to keep the bolt shut long enough for the bullet to leave the muzzle are just too great to be practical. (You don't want the bolt to extract the case before the bullet has left the muzzle as there would be too much high pressure gas venting back into the receiver - not good.)
So for higher powered rounds, you either lock the bolt in place eg by rotating it so lugs engage with recesses in the receiver, or you add a mechanism to delay the blowback operation long enough to have the chamber pressure reduced to a safe level before the chamber is opened, without resorting to stupidly heavy bolts with really stiff springs.

Delayed blowback systems have to use different mechanisms for "locking" because they get the impetus for their operation from a different place & direction. A locked, rotating bolt has to be rotated first, before it can move backwards, but in delayed blowback the first (and only) movement that drives they system is directly backwards, so there isn't any opportunity to effect rotation first.

And just for fun there are the hybrids! These use gas or recoil to unlock the barrel and blowback to shove the bolt backwards and "cycle" the action. Of course such lulz actions are mainly found in cannon as opposed to rifles.

Oh and not all locked breach action have to use rotary locking, there is also the fun worlds of tilt and toggle locking.

[Creative Vikings]

Anyone got a stencil of the catridge dimensions of the 7.62x51mm NATO?

[Celtic Colonies]

And just for fun there are the hybrids! These use gas or recoil to unlock the barrel and blowback to shove the bolt backwards and "cycle" the action. Of course such lulz actions are mainly found in cannon as opposed to rifles.

I evidently know very little about cannons then, that's new to me.

Oh and not all locked breach action have to use rotary locking, there is also the fun worlds of tilt and toggle locking.

Indeed, hence me using it as an eg (that and it was the variety of locking referred to in the question). Just couldn't be bothered expanding the post any more, I've a tendency to get caught up in horrible run-on sentences as I keep remembering more things that are vaguely relevant.

[Celtic Colonies]

Anyone got a stencil of the catridge dimensions of the 7.62x51mm NATO?

Would .308 Winchester be close enough?

[Crookfur]

On the missile the velocity isn't a issue and it could actually go a bit faster (up to mach 2.6 or so) but its the fuel to actually go beyond 5000m that you'll be hurting for.


Are you sure you want API as opposed to APFSDS? For ground applcaitions APFSDS tends to work a lot better and is likely going to give you a solid 100-120mm RHA penetration as opposed 70-80mm for an API load.

And yes the a 120mm recoiless rifle will be out performed my msot ATGMs as they tend to have larger calibre warheads or have top attack functions.

Okay, I see what you are saying the range is unrealistic. I guess a more realistic Banshee man-portable surface to air missile would be a two shot (having a multi-shot launcher might increase the probability of hitting the target) rocket launcher firing a 10kg fire and forget missile which has a maximum range of 5000m and a maximum velocity of around 700-900m/sec.

I do not know much about anti-armor warfare but how well do you think a high velocity 30x237mm DU APFSDS round would perform against armor? Could it penetrate or threaten the Stryker? Could it penetrate a Bradley IFV? If a sniper fired this at a M1A2 Abrams at relatively close range would he do more than just scratch some paint?

As for the power of a recoilless rifle ATGMs usually fire missiles with 3 to 9kg warheads while a 120mm recoilless rifle fires tank shell sized projectiles at around 13kg and they generally have a higher muzzle velocity than an anti-tank missle. Recoilless rifles would lack the guidance of ATGMs so top-attack firing is not possible. Anyway what are some of the pros and cons of using a recoilless rifle system instead of anti-tank missiles for an infantry anti-tank weapon and what roles are both weapons generally used for?

As I said for your proposed round you are looking at 100-110mm RHAe penetration, enough to deal with anything short of the current top armoured IFVs including early model BMP-3s.

To hurt an abrams with such a round you would need to get very close and try for the lower hull inside the tracks or maybe the engine deck from a building above the tank in short its not remotely practical.

As for recoiless rifles vs ATGMs

on one hand the recoiless rifle is cheaper and far far more versatile but on the other a ATGM system will be a bit lighter and more portable, have a much longer effective range (since its guided), a smaller firing signature (which in certain mdoels can be hidden or remote from the control point) and generally have a more optmised warhead (its not purely weight but also diameter and warhead layout, velocity is also no real benefit to penetration when you are dealing with HEAT rounds).

Big recoilless rifles and ATGMs generally do the same job with the great majority of ATGMs being introduced as RR replacements. You would only use recoilless rifles if you couldn't afford/access ATGMs.

[Nai Rotaun]

Army:
T65


Marines/Navy:
G36

[Purpelia]

Here is a question. In strait-pull bolt action rifles, how is the bolt locked into place when firing? Most rifles of the age use a rotating bolt that you manually slide into the locked position. But a strait pull has no such thing. So how does it lock?

[Galla-]

Here is a question. In strait-pull bolt action rifles, how is the bolt locked into place when firing? Most rifles of the age use a rotating bolt that you manually slide into the locked position. But a strait pull has no such thing. So how does it lock?

wat

K31 is rotating bolt...

You pull it back, and the bolt has cam tracks that force it to rotate.

[Senestrum]

Here is a question. In strait-pull bolt action rifles, how is the bolt locked into place when firing? Most rifles of the age use a rotating bolt that you manually slide into the locked position. But a strait pull has no such thing. So how does it lock?

Why doesn't the charging handle on an AK flail around wildly as the bolt rotates?

Answer: it is not directly connected to the rotating portion of the bolt.

[Spreewerke]

I took our K31 apart to check that out a couple years ago: everything rotates as normal except for the handle, basically.