Ian McCollum on the PTRD 41

NUTTERNAME

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Black powder...AKA 'Gun Powder' (there was no other powder at that time)...was around in the 1800's...they did have dice then, if that is what you mean????
 

Paul M. Weir

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Paul,

I wish you were my high school chemistry teacher.
What may surprise you is that I only learned the stuff about nitrocellulose in the last few days. While I knew a reasonable amount about black powder since my school and college days, I was fairly ignorant about modern propellant. So I went to Wiki and read up about it. I had always assumed muzzle flash and blast was due simply to unburnt propellant being expelled from the barrel and finally burning in the air. I was wrong in that it was the carbon monoxide produced due to nitrocellulose's oxygen deficiency that ignited when mixed with air. A sort of secondary effect rather than a primary (unburnt powder). Unburned powder would be an inefficiency/waste but carbon monoxide (CO) production would not be (CO is just as good a propellant gas as CO2).

So muzzle flash not being "wasted" propellant was an eye opener for me, an "that makes sense"/eureka moment and I could not resist the urge to share. There are other reasons for producing "flashless" powders, but efficiency/powder waste is not one of them.
 

NUTTERNAME

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My main point was concerning flash and blast and how a longer barrel can reduce those.
Flash being a light phenomena?.... and 'blast' being a destructive wave of highly compressed air spreading outward from an explosion?

Glad you found out that weapons in the 1900s and 2000s are not blunderbusses....So, how long would you make the 14.5 mm ATR to attenuate these flashes and blasts????

I assume your thermodynamics also came from Wiki?

(CO is just as good a propellant gas as CO2).
Oh boy. Carbon Monoxide is a fuel...Germans used it to run trucks off wood and coal...
 

NUTTERNAME

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Source = Hatcher's Notebook
Army ordinance tests of a 30-06 in a BAR found that only 29 1/4% of the powders energy is transfered to the bullet.

The other 70 3/4% is heat loss.

Broken down:
Heat to brass case = 131.0 calories.
Kinetic energy to bullet = 885.3 calories.
Kinetic energy to gases = 569.1 calories.
Heat to gun barrel = 679.9 calories.
Heat in exhausted gases = 598.6 calories.
Total from powder charge & primer = 2,864.0 calories.

Additional heat generated by bullet friction = 212.0 calories.
Total of one shot of 30-06 ammo = 3,076 calories.
 

Paul M. Weir

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Oh boy. Carbon Monoxide is a fuel...Germans used it to run trucks off wood and coal...
And heated my food and home for a dozen or more years until they switched from town gas (CO + H2) to natural gas. The eye opener was the amount of CO produced. From my post #17, 2 nitrocellulose base units would ideally produce 7 x H2O (water vapour), 3 x N2 (nitrogen), 3 x CO2 (carbon dioxide) and 9 x CO (carbon monoxide), IE 9/22 or 41% by volume. That CO cannot act as a propellant fuel as there is no spare oxygen while in the barrel. It's only when it leaves the barrel and mixes with air can it ignite.

Ignition can only occur if the concentration of oxygen (from air) and carbon monoxide (from propellant gasses) are temporarily high enough in bits of the turbulent region near the muzzle and the temperature is also high enough. Gasses heat up when compressed and cool when pressure drops, so called adiabatic heating and cooling. Allowing more pressure reduction by greater barrel volume will decrease the bulk temperature before it leaves the barrel. In addition the peak concentration (weight by volume) of CO will be reduced at the muzzle. Those two will combine to reduce the fraction of CO that will ignite as it mixes with air.

What would be the ideal length of a PTRD/PTRS? I have no clue, none whatsoever. However I will suggest the Lee-Enfield Mk 5 (aka Jungle Carbine) as an illuminating example (literally). The Mk 4 had a 25.2" barrel and that was shortened to 18.8" in the Mk 5. The designers felt the need to add a flash suppressor despite the fact that the flash suppressor actually increased the recoil energy by 14.3% or 10.2% *. So I can only deduce from that that the flash suppressor was quite, quite necessary due to the shortened barrel. I very strongly suspect the designers of Soviet ATR had similar considerations in mind when designing their ATR, despite the extra weight and length. I'd be surprised if they didn't do some experiments with different barrel lengths.

* Recoil energy of Mk 4 = 13.64 J, of Mk 5 = 19.14 J of which 1.95 J from flash suppressor = 14.3% of Mk 4 or 10.2% of Mk 5 totals. See: https://en.wikipedia.org/wiki/Lee–Enfield_Rifle_No._5_Mk_I_(Jungle_Carbine)
 

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I once braved an ice age, in a previous life, with nothing more than the frictional heat generated by projectiles in overly long barrels....
 

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“Evaluation of Degryaryev and Simonov anti-tank rifles based on the reviews of privates, Sergeants, and officers of anti-tank rifle units


  1. Simonov’s rifle starts jamming after only a small amount of fouling in the chamber, after 10-15 shots. Degtyaryev’s rifle is flawless in its action. I knocked out a tank near Skopishki at 300 meters (with a BO-32 bullet). – Sergeant Pazharduk, 665th Reg., 216 Div.
  2. The Degtyaryev anti-tank rifle has an insufficient rate of fire for fighting tanks, reloading takes too long. The rate of fire of Simonov’s rifle is good, but heavy for attacking. Their weakness is that they are not used with the whole unit, but split up among companies and platoons, which removes the ability to fire in groups on tanks and other targets. BO-32 bullets have weak incendiary properties, BO-41 bullets are good. – Sergeant Pikalov, 346th. Div.
  3. The PTRD is an excellent weapon, works flawlessly. The PTRS jams often when there is any dirt in it or when the lubricant freezes. – Artillery Quartermaster, 1166th Reg., 346th Div. Jr. Military Technician Prikhodko
  4. The PTRD is flawless in battle, never has any jams that create difficulties on the battlefield. However, its weakness is that it has no magazine. The PTRS has a high rate of fire, and is convenient to carry, as it can be taken apart and put back together quickly. Its drawback is that it has many jams that cannot be fixed on the battlefield, the assembled rifle is heavy, the round casings burst often, and the chamber is fouled, which results in jams. 4 medium tanks were knocked out with anti-tank rifles from 300 meters (BO-41 bullet), and three armoured cars from 200 meters. – Artillery Quartermaster, 1168th Reg. 346th Div.
  5. The PTRS has sufficient rate of fire, and sufficient penetration for a light or medium tank. Its drawbacks include jamming in dusty conditions and case expansion, which makes reloading difficult.
    The PTRD is light and mobile, reliable in cold and dust. The penetration is sufficient. Drawbacks include a lot rate of fire. During fighting in Lithuania and Latvia 3 tanks were knocked out at a range of 250-300 meters with incendiary bullets. – Commander, 1st Company, 1168th Reg. 346th Div. Captain Gotozhkov
  6. The PTRD is superior to the PTRS, its penetration is good. With three aimed shots, an enemy machinegun was destroyed at 250 meters. Company commander, 346th Div. Sr. Lieutenant Deritz
  7. The anti-tank rifle is a good weapon for destroying enemy strongholds, armoured cars, and other weapons. – Sr. Sergeant Fedoseev
  8. The penetration of the anti-tank rifle at 100 meters is 45 mm. The rate of fire of the PTRS is 10-15 RPM, of the PTRD is 8-10 RPM. The rate of fire is good. The anti-tank rifle is very effective at destroying enemy machinegun nests. The anti-tank rifle likes cleanliness, good care, and constant lubrication. – Jr. Sergeant Kvichko
  9. Anti-tank rifle units prefer to be armed with PTRD rifles, as they are lighter and more reliable. Currently, AT rifles are rarely used against tanks, as our units are saturated with AT artillery. They are normally used to destroy cars, prime movers, and light armoured cars. – Artillery Quartermaster, 417th Div. Malinin
Conclusions
  1. In the second phase of the Patriotic War, when the Red Army went on the offensive on all fronts, our forces became saturated with AT artillery, improvement of armour on medium tanks and increased numbers of heavy tanks, the importance of anti-tank rifles as anti-tank weapons decreased drastically.
    The anti-tank rifle lost its power as an infantry anti-tank weapon. Artillery effectively fights tanks now. The anti-tank rifle, due to its high precision, is now used against open enemy concentrations, armoured cars, and APCs. This is natural, given the state of equipment of infantry at this time.
  2. Almost all anti-tank rifle units speak well of the PTRD: light to carry and flawless in battle. Some wish to increase its rate of fire, others mention that the rate of fire is the only good quality of the PTRS. There are no positive reviews of its reliability, only negative. After 10-15 shots, it starts jamming, and these jams are hard to fix, consume a lot of time, which is unacceptable in modern fast-paced battle.
    The PTRS is unusable in battle, and its subsequent production is pointless.
  3. Retain the PTRD in production, increase its rate of fire.
51st Army HQ Chief, Major-General Dashevskiy
Chief of the Artillery HQ, Colonel Shvedkov
September 28th, 1944″
 

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Flashy-Blasts Ukraine...


We also see the blasty-flashies attenuated nicely in the KPV machinegun....

 
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NUTTERNAME

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Very interesting test using a tungsten round from a Lahti. I have worked as a test engineer and am very hard on even myself as far as pre-test thought. This test shows how even these soft steel plates disrupt a TC round. I wish he had shot on a soft plate (1/4 in) and as hard armored plate as he could get 25-30 mm, but the test does show something interesting. The 'crumble' of the point of the penetrator. skip to 5 min if you want. The main point is that the Germans skirt armor was very analogous to this soft plates he is lining up.

 
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