GTG ?

You didn't even attempt to look for any threads already talking about this did you?

He is asking about 55 gr.

The 64 and 75 have many current reviews here in this thread and on You Tube but I am not seeing much on the 55 either (was $9.99/20 with free ship PSA recently):



http://www.ar15.com/ammo/project/Self_Defense_Ammo_FAQ/index.htm

http://www.ar15.com/forums/t_3_16/688331_Speer_LE_64_Grain_Gold_Dot___Velocity__Accuracy_and_Terminal_Ballistics.html

http://www.ar15.com/forums/t_3_16/692071_64gr_Gold_Dot_with_no_primer_sealant.html

http://www.ar15.com/forums/t_3_16/691421_75_Grain_Gold_Dot___Any_Info_.html

http://www.ar15.com/forums/t_3_16/691585_Gold_Dot_75_Grain_Nickel_Case.html

http://www.ar15.com/forums/t_3_16/693784_Speer_Gold_Dot__223__64gr_or_75gr_.html

Yes I did but the search engine here is very limited and I used "55 grain"

Searched the web also, see below - I wanted independent data

55 gr GD data

I have about 600rds of this...good stuff.  Accurate.  

It expands to upwards of .50" and meets the FBI penetration standards of 12" in bare gel and through heavy clothing (penetration around 14"). It also performs decently through drywall, plywood and even steel. The one barrier this load struggles with is safety glass. I recall it only achieves about 7.5" of penetration in gel after passing through safety glass. It should more than suffice for home defense or hunting smaller whitetail deer. But if I were an LEO working patrol, I'd probably prefer the 64 grain version of the load just because it performs better through glass, a type of barrier which patrol officers will find to be common when dealing with people inside vehicles.

Yes, the manufacturer's test of the 5.56 pressure 55 grain Gold Dot as shown in their LE Rifle Data Book shows rather unimpressive autoglass results. DocGKR however has reported some better results in other ATK testing (perhaps for ICE/DHS considering the barrel length?):



His testing of the .223 64 Grain Gold Dot out of a 16 inch barrel does show superior autoglass performance:

From the Ammo FAQ

I know this is a tech forum and I don't have anything to add other than, DANG it's good to see you Charging Handle....   It feels nice to see an old name around here.

Does anyone have a REALISTIC muzzle velocity for this load?
Speer lists their velocity as 3240 from a 24 inch barrel.  No patrol/home defense carbine that i know of uses that long of a barrel.

Here is a ton of info on the 64gr gold dot,this should give you a pretty good idea of what velocity you will get

http://www.ar15.com/forums/t_3_16/688331_Speer_LE_64_Grain_Gold_Dot___Velocity__Accuracy_and_Terminal_Ballistics.html

Odd as it seems, 24" is, IIRC, the industry standard length barrel for test barrels.