#5667 1903 muzzle velocity

[firebugs]

The listed MV for the 1903 in game is 783 m/s.. that's way slow. IIRC the true MV of the 1903 was about 25-50 Fps ( roughly 10-20 m/s) faster than the M1 Garand.

M2 Ball was stated at around 2750 fps (830 m/s), 150 grain FMJ flat base projectile, copper or gliding metal jacket filled with a solid lead core, or M2 AP which was also a FMJ flatbase projo, except it had a tungsten carbide penetrator as well as a lead plug. 165 grain. None the less, still chugging along at 2715 fps (828 m/s).

Either way I can tell you right now, unless things change during the BETA before the release I can find US military documents that will 1) say that your MV is off, and 2) provide a tested and true G1 (what you use) ballistic coefficient that is significantly higher than the one you've given the .30-06 weapons in game.... I'm assuming you just used the K98k's .21 G1 BC...

Links

http://www.inetres.com/gp/military/infantry/rifle/30_ammo.html

Guess what, I have military .30-06 cases (1940's dated even), I have IMR 4895 powder, military primers, and I have THOUSANDS of M2 150 gr. FMJ bullets and an M1 Garand... A live fire test is going to happen next time I'm home for real-world verified data.

Edited August 8, 2011 by firebugs

[firebugs]

Boom goes the dynamite. Pay particular attention to page 19 "Cal. 30 Ball M2". -- there is a typo for 400 METERS.. dunno wtf it's about. No way it goes 2025-1175-1560. Use the yards scale.

http://www.google.com/url?sa=t&source=web&cd=3&sqi=2&ved=0CCQQFjAC&url=http%3A%2F%2Fwww.bodyarmorcompany.com%2Fdownload.php%3Ff%3DMILSTD662.pdf&rct=j&q=external%20ballistics%20M2%20AP%20M33%20m80%20ballistic%20coefficient&ei=F2w_Tr64HPLC0AGry5GMBA&usg=AFQjCNFGQ5gv2XxdSfQGgGKGdTl16WQfkg

Might even be worth looking at your .50 bmg specs.. it has both aircraft (36" barrel) and ground(45" barrel) info.

Edited August 8, 2011 by firebugs

[GOPHUR]

I'll look at these this week. Something isn't right with all this data being fubar.

Put whatever needs looking at in this thread fire and I'll look at it later this week.

[firebugs]

M1903, M1 Garand, and M1918 "BAR" all fire the same rounds.

I don't know if you intend to use .30 M2 Ball (Lead core, fmj flat base 150 grain bullet) or .30 M2 AP (Hardened steel core FMJ flat base AP 165 grain bullet).

Both were issued to troops for use in small arms (issued pre-loaded in M1 8-rnd clips, definitely used in the BAR for penetrating barriers etc. and snipers prefered the AP rounds because of their flatter trajectory-- they were loaded hotter.)

I'll start with M2 BALL.

MV is 2800fps (853 m/s) according to this document. According to others it's as low as 2750fps (838 m/s)-- A minor difference IMHO-- could easily be a shot-to-shot variance (extreme spread of 50fps or more is normal), anywhere in between is fine. The M1 garand and M1918 have the same length barrels as the m1903 (24 inches), but the autos bleed gas to the piston systems under the barrel, and in general loses about 30-75 fps (10-25 m/s). Again those are averages, individual weapons will vary.

With that said, Here is the real-world velocity data for M2 ball starting at 2800 fps (853 m/s), every 100m going to 1000m (I'm excluding 400m as it's an obvious typo).

0m- 2800fps (853m/s)

100m- 2540fps (774m/s)

200m- 2275fps (693m/s)

300m- 2025fps (617m/s)

400m-Omitted

500m- 1560fps (475m/s)

600m- 1345fps (409m/s)

700m- 1175fps (358m/s)

800m- 1040fps (316m/s)

900m- 950fps (289m/s)

1000m- 910fps (277m/s)

Now here comes the issue. Your ballistic computing program is a G1 model system. That's meant for plotting the trajectory of round-nosed, flat base artillery shells. However, it has been used as the standard in small arms for a LONG time, and is more or less the standard all around. Unless something is otherwise stated, a ballistic coefficient without a "G7" or "G8" in front of it is accepted to be a G1 BC. With that said, G1 programs don't handle pointed FMJ bullets with exact accuracy, meaning if I plug in a G1 BC that matches muzzle velocity, and velocity at 1000m, it likely won't match at 800m, and especially not at 200-500m. You can get it to be close, but it will never match real-world numbers, which is what are presented in this document. To do that you would need a G8 program meant for flat-based spitzer projectiles (like M2 Ball). I don't see that happening, because then you need G7 calculators for bullets like the German and French 8mm FMJBT bullets.

IMPORTANT: Ballistic coefficients are not interchangeable between different G# calculators. a .615 G1 BC could be roughly equal to a .310 G7 BC. Hence a great deal of confusion. Just understand that G1 calculators get you very close, but not exact to the real world, and from now on I will only mention G1 information, as that is what pertains to this game.

NOW, with all of that explained, the closest I can come to those numbers at sea level is a G1 ballistic coefficient of .355 for .30 M2 BALL. Out to 700m (max render range for EI as of 1.34.0.23), it is within 15m/s of real world data.

Now, onto the .30 M2 AP 165 grain round.

Velocity:

0m- 2760fps (841m/s)

100m- 2535fps (772m/s)

200m- 2325fps (708m/s)

300m- 2115fps (644m/s)

400m- 1915fps (583m/s)

500m- 1730fps (527m/s)

600m- 1560fps (475m/s)

700m- 1390fps (423m/s)

800m- 1255fps (382m/s)

900m- 1140fps (347m/s)

1000m- 1070fps (326m/s)

The G1 BC that closest matches the M2AP real world data is around .415, and that is within 7m/s of the real world data out to 700m.

I'll do the .50bmg stuff in my next post.

Edited August 9, 2011 by firebugs

[firebugs]

Well now. The .50bmg. What a headache. You have M2 ball, M33 ball, M2 AP, M1 incendiary, M8 API (starting 1943), 3-4 types of tracers, M20 APIT......

Main problem. I don't know exactly what rounds you're using, and to help out even more (sarcasm), bullet weights and velocities vary a ton even within the same class of ammo.

So after careful consideration, I'll wait for you to tell me what to look for, if you even want me to look before I start throwing numbers around

Edited August 9, 2011 by firebugs

[firebugs]

I would just like to add that I hope this is an eye opener not only specifically to the .30-06, but to all of the small arms rifle/LMG/MMG calibers in the game.

If a 165 grain FMJ flat base bullet has a BC of .415, then how can a heavier Mk7 ball, 174 grain flat base FMJ of nearly identical diameter (.004" bigger around) only have a BC of .251?

Even worse, how can a 198 grain FMJ with a boat tail (German s.S. Patrone) have a BC of only .30 or even worse .21?

Food for thought.

[GOPHUR]

I don't really give 2c about the bc. This isn't a recreation this is a simulation. In a simulation the results are what matter. We're lucky that the physics is good enough that expected results are generally created when using real world data. That's a nice bonus. Still I like things to work as expected.

This is generally why I don't pay much attention to these posts. Telling me the bc is off doesn't mean squat to me (yes I understand bc &c) without telling me what the problem is that this creates in the game simulation. Does it still hit on target at the range? Is the dispersion in the expected range? Does it kill what it should and not what it shouldn't? These are the important things to me. You need to make me realize why I should spend time on this instead of a hundred other things that seem much more important.

[firebugs]

Energy on target- Biggest issue for me. The K98k for example, at 200m it has about 60% of the retained energy it should have. At 400m, 36%. By 700m, approximately 32%. Imagine the effect this has on aircraft in early tiers, shooting .30 cals at 100-400m.

Flight time- Rounds slow down faster, thus take longer to get to their destination. Again, I'll use the K98 as an example, it takes over a full second longer than it should to get to 1000m. If you kept the same time-out time for it (flight time until it disappears), it would fly about 500-600m further than it currently does.

Lead for moving targets- More lead is required for hitting moving targets as a result of longer flight times. With the K98k, and a sprinting target (10mph) at 400m, the shooter has to aim one entire meter extra in front of the guy running.

Elevation change between range settings- Yes the range settings match up to bullet impacts at the 100m range intervals, but in between those ranges, it's a game of "how far above/below my crosshairs should I aim?". With the K98k at 550m with the weapon sighted for 500m, in WWIIOL you have to aim 1.03meters high (Aiming for head on a standing person means hitting in the legs or missing between them). In real life with the same shot and 500m zero you'd only have to aim 0.41 meters high (Aiming at head hits in the lower torso-- with 70+% more energy).

If the difference between what you have and what really does happen wasn't so HUGE, I wouldn't have so much of an issue with it. But if you overlap the true trajectory/energy graph of some of these rounds with what's going on in game, it's shocking.

I've said it before. If you changed all of the rifle BC's to anywhere between .35 and .45, I would not be able to tell something was definitively wrong. This .21-.31 business, though, was an easy spot once I knew what I was looking for.

The reason for that is that as BC increases, the difference between two given BC's decreases... For example the jump from .10 to .20 is giant, but the jump from .5 to .6, although noteable, is nowhere near as drastic.

edit to add: What is hurt by changing them? The only thing I can think of is armor penetration. The only time there is penetration with these calibers as they are is within 100m. 100m won't change that much. This is mainly going to change 200m+. So if it doesn't penetrate point blank now, it won't penetrate after you change the BC. And if it penetrates now out to 10m, it might penetrate at 15m (?) after you change BC. (tank) Armor penetration will simply not be affected significantly.

Edited August 11, 2011 by firebugs

[jwilly]

Just to address that last point...

If rifle bullets behaved like FMJ instead of steel AP, armor penetration wouldn't be a long running game-weirdness issue. Maybe someday that'll get fixed.

Edited August 11, 2011 by jwilly

[DOC]

it's not about "getting fixed" ... the games original development crew wanted rifles to be armed with AP rounds not ball

the question is not whether it's broken it's whether we change that reasoning

remember, we're not recreating anything use-wise we're just simulating weapons ... WWII could have been fought with AP instead of ball and if it weren't for cost it probably would have been a lot more common (yes I know it's less effective versus a human body not behind cover) ... having AP ammo in rifles is only "wrong" because it wasn't common, not because it was impossible

so argue why we need to spend lots of time reauditing the entire rifle ammo side of the game (at some cost) with all this other work we have to do ... not on the basis of it being broken but of it being not the result the players want

don't forget fun as part of that result

[westy]

Making tanks/armoured cars more of a target for anti-tank infantry and less of a target for rifle infantry could be a good thing.

[DOC]

yeah, understood

what tank is currently facing problems from regular rifle infantry ?

I know about the armoured cars, some hate their current vulnerability but if you're including tanks in that vulnerability, I have to call this as hyperbole really and that doesn't get a lot of traction

armoured cars, I get ... an audit of all rifle ammo at this stage isn't going to happen as we are snowed under with many other matters much more urgent to the games on going health

at some point when things are more relaxed, an audit along those lines might happen (no one here is actually opposed to the idea just the task being set really) ... it would be a bigger task than you probably think

[westy]

Groovy and thanks Doc!

It is mostly the armoured car's vulnerability to rifle that is a bit annoying. And don't get me wrong, I am an infantry player and I believe that all levels of armour should instill dread and fear in us poor little meat-sacks!

Great stuff coming down the pipes from Rats! Thanks and keep up the good work! This is truly the only game I have played for most of the past decade. Its that consistent and addictive.

[GOPHUR]

M1903, M1 Garand, and M1918 "BAR" all fire the same rounds.

...

The differences in these two sets of numbers is ~3%. Tha't enough to be completely negligible in my book. The game creates greater differences shot to shot.

I shot the Garand on game on the range. My speeds were roughly 10m/s slower at 1km and more at closer ranges. Not enough that I'm willing to spend time on an audit over other needs.

"Energy on target- Biggest issue for me. The K98k for example, at 200m it has about 60% of the retained energy it should have. At 400m, 36%. By 700m, approximately 32%. Imagine the effect this has on aircraft in early tiers, shooting .30 cals at 100-400m."

I wasn't looking at plane numbers but I can at some point. I can switch the ammo out. The problem here is what I call "Hoofism". Hoof was the NASA boy genius (literally) who programmed it all. You're looking at the numbers and expecting them to add up to a result.

"Flight time- Rounds slow down faster, thus take longer to get to their destination. Again, I'll use the K98 as an example, it takes over a full second longer than it should to get to 1000m. If you kept the same time-out time for it (flight time until it disappears), it would fly about 500-600m further than it currently does."

In our effective ranges we are talking about the differences in time that is so small that players cannot likely perceive it. It's a real world argument coming from an obvious enthusiast that has so little bearing on the simulation as to be moot.

"Lead for moving targets- More lead is required for hitting moving targets as a result of longer flight times. With the K98k, and a sprinting target (10mph) at 400m, the shooter has to aim one entire meter extra in front of the guy running."

And changing how it works so the numbers look good on paper means a new learnign curve for every participant in the simulation. To what purpose? To look good on paper? For a 3% difference? C'mon.

"Elevation change between range settings- Yes the range settings match up to bullet impacts at the 100m range intervals, but in between those ranges, it's a game of "how far above/below my crosshairs should I aim?". With the K98k at 550m with the weapon sighted for 500m, in WWIIOL you have to aim 1.03meters high (Aiming for head on a standing person means hitting in the legs or missing between them). In real life with the same shot and 500m zero you'd only have to aim 0.41 meters high (Aiming at head hits in the lower torso-- with 70+% more energy)."

Can't really argue there because the system works to adjust the trajectory of the fire point (not the gun) so that the round will land where you've input. Simulation not recreation. I never use the range finder so I'mnot best to ask about this.

"If the difference between what you have and what really does happen wasn't so HUGE, I wouldn't have so much of an issue with it. But if you overlap the true trajectory/energy graph of some of these rounds with what's going on in game, it's shocking."

Take the k98. Draw me a graph. Then tell me what you want me to put in the numbers and I'll go PLAY it. (I really don't give a poop about the graph but I'll allow that it too will be shocking). If I'm shocked. I'll spend more time on this topic. If not. I won't. I only offer to in the first place because I have a natural interest in this stuff. Work wise the number oif things that are on my plate that are vastly more important than this is quickly approaching the infinite.

But I'll bite because I know you and many of our players are passionate about this type of thing, and well, I am too I guess =]

[firebugs]

Drop the zeroes on the 2nd graph to get it in meters... roughly 22 METERS difference at 1000yd. LOL if I were to fire WWIIOL bullets out of my K98k with the sights set to 1000m, I'd have to aim 6 stories above the target to hit it..

I understand that most people couldn't tell you the drop in inches/cm/MOA/Mils of any round at 200yd, 300yd etc... and if you said "Ballistic coefficient" to the majority of the playerbase they'd give you the "HUH?!" face.

None the less, I think my point all along has been that it's not correct to historical/real world values-- being one of the selling points of this game it would make sense to me to make a push for as close to real-world results as are possible. If you can live with it being off (and I can totally understand there being a LOT more important things than this to fix first), then I'm sure I can, too

I just know it makes me feel warm and fuzzy inside when I play ARMA2 and can use my .308 drop sheet in the game with success.

Edited August 12, 2011 by firebugs

[GOPHUR]

Yeah those BC aren't matching what I'm finding either. They were last audited in 2002 for the most part. I remember that audit being huge and pretty thorough so the bc errors really surprise me. I'll need to go back and check the logs in the source to see what was used. I assume G1 too but I'll want to back that up.

I'm going to keep this on the plate just a little too busy at present to go into this big an audit.

[firebugs]

This is my honest-to-God estimate of what all of the rifles/lmgs in the game should be. I'm not trying to get an edge in, no side bias etc.. I couldn't care less... Just as a weapons enthusiast.

7.92x57mm SS patrone/Mk2z ball (k98, mg34, mg15, 7.92 BESA coax etc.)- .545-.565

.303 brit mk7 ball (Lee enfield, bren, .303 vickers/brownings)- .415-.430

.30-06 M2 (1903,m1,m1919,m1918, 7.62 co-ax)- .355-.365 (ball) .410-.420 (AP)

7.5 French (MAS36, fm29 etc.)- .340-.350

8x50mm Ball D (1886 Lebel)- .540-.560

Understanding that a G1 calculator isn't going to give you a perfectly correct trajectory to begin with (especially as range increases, G1 calculators overstate velocity/energy), and given the shapes, diameters, and masses of the above rounds, those BC's will get you extremely close.

How close? Even if you gave me tools that told me exact velocities at exact ranges and exact flight times, I could never get past the margin of error that exists in the real world (difference from shot-to-shot, rifle to rifle, bullet to bullet) to come up with anything close to definitive.

Edited August 17, 2011 by firebugs

[GOPHUR]

Thanks FB. I'm not going to audit them today but remind me from time to time when the crunch isn't so great and I'll do the legwork on some changes.

I'll have to cross reference them natch.