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.50 ammo question.
Nwcid
Member Posts: 10,674 ✭
I am not able to find a good answer to this one, so time to ask here. I am looking at some different .50 BMG [:D] ammo. One that I am looking at is Spotter rounds. From what I have been able to find it is a different size round, but you can use the bullets to load 12.7x99 rounds, is that correct? It sounds like it is a tracer the "smokes" when it hits a target. Would that not be the same as shooting an APTI, just with a different flight path? Is there anything cool about these if you have Incendary or APTI rounds?
Comments
The 50 Spotter-Tracer is a shorter cartridge and was manufactured with a very specific purpose in mind. Here is a response that I got from an acquaintance of mine when I was looking at these cartridges for a project:
50 Caliber Spotter-Tracer M48A2
Pulled bullets from US GI 50 Caliber Spotter Tracer ammunition. Spotter guns were mounted coaxially with the 106mm recoilless rifle. The gunner fired cheap spotter tracers until he was on target, then blasted away with the 106mm main gun. As one reader pointed out, this avoided giving away the gunners position until the main payload was delivered. The spotters left a bright red trace out to the target, then exploded on contact producing a yellow flash and large puff of smoke. Much larger than M1 Incendiary. Government specs called for a minimum of 1500 yard trace. At only 1745 feet per second, this is a very long tracer burn time.
These bullets were carefully pulled with a collet type puller, so no pull marks! Photo shows comparison to US M33 Ball bullet. Profile ahead of the cannelure is the same, but the area below the cannelure is much longer to allow for the extra tracing compound. This bullet is nearly all pyrotechnic compound. Only a short cylindrical lead slug, about 1/2" long, in the center. The back half is all tracing compound, the front half is all flash and smoke mixture. Some models have a small primer mixture in the nose, but it was later determined that the mix goes off all by itself upon impact, so the primer mixture was dropped.
These bullets were intended only for low pressure applications. Spotter ammunition was loaded to 1745 feet per second, at 38,000 PSI. While the bullet fits a standard 50 BMG case just fine, it was not designed to handle the 50 BMG pressures. If loading these in a 50 BMG case, drop your load down to approach the original velocity and pressure. This is important. This warning is not like the ones on the toaster where it says "Do not make toast while standing in a tub of water." This one's important!
Earlier in life, I loaded a few of these for my 50 caliber rifle. Not knowing too much about loading 50 caliber stuff, I decided it might be safest to use the original GI loading. So I pulled the 650 grain bullets from the 50 BMG ammo and placed these bullets right on top of the original powder load, not giving a second thought to the fact that these spotter bullets weigh 813 grains! Oddly enough, most of them worked just fine. Very spectacular trace and huge flash. However, I had a few explode in flight, some almost right in front of the gun! Fortunately, I was there by myself so nobody got hurt, and more importantly nobody saw my dumb trick! What happens, is occasionally the high pressure gas seeps past the tracing compound, past the lead slug, and into the explosive mix. This stuff is all in there tight enough to seal against the 38,000 PSI, but possibly not against the higher pressures of the 50 BMG. Admittedly, my home brew that night was no doubt a somewhat high pressure load, but it's something to keep in mind when using these. While they are safe at the low velocity and pressures, there is an unknown point where they are no longer safe. And I was able to exceed that point using standard cases with standard powders. So be careful, and they can be a lot of fun. At the low velocity these were designed for, they produce a very bright, high-arc trail out to the target. Almost like playing "artillery" on a small scale!
And:
Cartridge SA.50" Spotter Tracer
This small arms ammunition is fired from the Cap.50" Spotting rifle M48 which is mounted co-axially with 106mm RCL gun and operated with the same trigger mechanisam.The spotter rifle is used to predict the correct range and trejectory and ensures a positive hit on the target i.e enemy tank by the Round 106mm RCL HEAT.Firer gets great tactical advantage of .50" rifle for accurate lying of the RCL Gun for first round hit on the enemy. This ammunition is similar to American Cartridge Spotter Tracer Calibre .50" M48. The design of this ammunition is similar to a small complete round.It includes cartridge case,percussion cap, propellant charge and bullet with spotting and tracer compositions.
The cartridge case of the brass is of rimless type, formed cap chamber at the base provided with two flash holes and an anvil. The mouth of the case coned onto the body of the bullet. percussion cap is boxer type, consists of a brass cap in which loaded with a cap composition(i.e FA 956)in form of pellet which is lead styphnate based.The propellant charge is made up of Nitrocellulose, Diphenylamine, Centralite and Potassium Sulphate or Potassium Bitartrate.
The bullet is of composite type and streamlined.It consists of three parts which are contained in outer envelope of copper opened at top . The first part consists of coned aluminium sleeve which is closed at the top and is positioned within the ogive of outer copper envelop e. Aluminium sleeve is assembled with spotter composition SR 379B and cap igniting .Second part is lead core with a step at the upper end to take the end of the aluminium sleeve ,is pressed into the envelope. Third part is steel base which is bored at the lower end, is fitted below the lead core.The recess of the base is filled with tracer composition {SR 390=0.324 grams], booster charge [SR 390 + sr 370 =0.292 grams]and primary composition [SR 370 = 0.194 grams].
This ammunition is manufactured to Governament of India,Ministry of Defenc,to Specification No.CIA 4201and Drawing No.IQV 24 GF.
Specifications
PHYSICAL CHARACTERISTICS
Total length of ammunition : 114.81 mm(maximum)
Total mass of ammunition : 107.00 +/- 1.99 grams
Mass of bullet : 53.135 +/-0.648
Mass of case : 45.07 grams
Mass of cap : 0.750 grams[approx]
Explosive fillingin cap : 0.085 to 0.105 grams
Explosive filling in bullet : 2.8215 grams
Propellant[ACM] : 7.00 grams[approx]
Net explosive content : 9.9265 grams
PERFORMANCE CHARACTERISTICS
Muzzle velocity : 535 +/- 9.1 m/s
Max.range for visibility of spotter smoke : 1100 metres
SPECIAL FEATURES
This ammunition is fired only to save costly RCL ammunition.
QUALITY
The raw materials used for componets are tested by independent Quality Assurance Department.During manufacturing stage, quality surveillance by both producer and army's representatives are provided All the major components i.e case cartridge, bullet filled,cap filled,and propellant are test-fired and only passed proof components are taken into final assembly of the ammunition. The complete round also proved for
[a] Velocity Pressure[c] hangfire [d]consistancy
[e]tracer functioning [f] spotter functioning
[g] rough usage test.
SAFETY
The cap being percussion type,gets intiated only if get blow.The ammunition is therefore safe during manufacture,transit and storage
RELIABILITY
The spotter round adequately predicts the correct range and thetrajectory and ensures a positive hit on the target by RCL HEAT round fired.
SHELF LIFE
The shelf life of the ammunition is 5 years.
I was pursuing this cartridge from another aspect which didn't include the use of the bullets at all. The area of the country that I live in precludes using a bullet like this due to the extreme fire hazards.
If this is interesting to you, make sure that there are no restrictions on using such a bullet in your area.
Check to be sure that they are legal to own and shoot.
Pay close attention to the quotes below and to the loading suggestions so as not to run these bullets at the top end velocities of the standard 50 BMG cartridge. Placing yourself and others in imminent danger just for a bit of fireworks doesn't make sense to me. Enter at your own risk.
quote:Spotter ammunition was loaded to 1745 feet per second, at 38,000 PSI. While the bullet fits a standard 50 BMG case just fine, it was not designed to handle the 50 BMG pressures. If loading these in a 50 BMG case, drop your load down to approach the original velocity and pressure. This is important. This warning is not like the ones on the toaster where it says "Do not make toast while standing in a tub of water." This one's important!
quote:However, I had a few explode in flight, some almost right in front of the gun! Fortunately, I was there by myself so nobody got hurt, and more importantly nobody saw my dumb trick! What happens, is occasionally the high pressure gas seeps past the tracing compound, past the lead slug, and into the explosive mix. This stuff is all in there tight enough to seal against the 38,000 PSI, but possibly not against the higher pressures of the 50 BMG.
Best.
I know it reads like I'm being overly cautious, and maybe I am. Glad you're aware of the potentials.
I've been working with some of the data on the .50 S-T in order to build up a rifle around this cartridge. Some of the basic work indicates that it can be nearly as good as the full size .50 BMG without the length and massive amount of powder. The BMG is pretty inefficient from the start and the .50 S-T is just making better use of less powder and in a shorter case. Sounds familiar, doesn't it?
The shorter cartridge doesn't help much with the design of the receiver since the diameter has to be the same as the BMG but it can be a little shorter to save on some weight and firing pin travel (lock time) of course. There is one group marketing this right now and maybe a couple of others on the way into production shortly.
Best.