What is the difference?  When you shoot it, can you tell which one you shot?  Does one last longer?

Thanks,
Michael

I think the spotter one blows up into a small smoke/dust cloud on impact

I thought that the spotter tracer was loaded to simulate the trajectory of artillery for faster sighting of the big guns, but I could be wrong.

Here is a video of blue tip... if anyone cares.  3.1 megs.

Spotter tracers are pretty fun, they do make a nice big puff of smoke when they hit.  I know a guy who buys the pulled bullets and loads them in the BMG.

Quoted: The S-T is meant primarily for the 106 recoiless rifle. The ballistic curve is pretty much the same. We chamber a few BFG-50's in spotter tracer. They are infrequent sellers, but we do sell a few a year. I'm thinking of getting a BFG carbine in S-T.

Is he refering to the cartridge? or to the projectile though?

The S-T tracer was loaded with WP to make a flash when it hit the target (was there HE also?)

The US Miliatry usually only loaded 12.7x76mm (or was it 79mm?) for it for the 106mm RCLs spotter rifle.

The UK and Israel did load 12.7x99mm with it, as spotter rounds for the 105mm L7 gun (US M68)

Spotter tracer loaded in 50BMG travers MUCH slower than any other 50BMG round, around 1800 fps. Any other tracer, M-17, APIT, etc, will be clipping alang around 2900 fps so that is the real difference you'll see in flight.

Spotter tracer also lights right out of the barrel where other tracers may not be visible for several yards after leaving the barrel.

no idea what version of trace that is out of the barret... buddy shooting it out of his barret tho.

Quoted: Spotter tracer loaded in 50BMG travers MUCH slower than any other 50BMG round, around 1800 fps. Any other tracer, M-17, APIT, etc, will be clipping alang around 2900 fps so that is the real difference you'll see in flight. Spotter tracer also lights right out of the barrel where other tracers may not be visible for several yards after leaving the barrel.

If its only doing 1800fps then its not .50BMG its the shorter case version.
The BAT was that slow.

If it is in the long case then it was loaded for UK/Isreali use for spotting for the 105mm tank gun.

I dont think you could download the BMG case enough to get 1800fps, that would be too much void and you'd probably get either a explosion or a squib.  Unless you used a really odd propellant or some kind of wadding.  The .50 Spotter round used with the 106mm BAT used a shortened case, shorter even than the .50 Vickers (which, for a long time is what I thought they WERE using, then I found out it was a unique, made for the purpose cartridge case)

Spotting for the tank gun actually would streatch the .50 BMGs performance, it needed to be up over 3000 fps just to match the HESH/HEP rounds velocity, much less HEAT- forget about sabot, it would be 1000 fps higher.  Even the old non-finned sabot round was over 4000fps.

The US didn't use a spotting gun on our tanks, we built very expensive and coplicated steroscopic optical rangefinders and mechanical ballistic computers, like the fire control directors on warships, that usually spent most of their time being worked on, since tanks bounced around a LOT more than ships did.  

The British developed the spotting MG idea, which not only gave them quicker reaction time (at the expense of range) but also gave them a limited shoot on the move capability.  If your tracers were striking the other tank, your main gun would hit it too unless you fell into a hole or hit a big rock exactly as your gunner pulled the trigger.  With practice, gunners could even adjust for the difference betwen the HESH and Sabot on the fly and still hit the target out to 1800m.