Speer #24446 (.223 Gold Dot, 55gr) Testing

[Unobtanium]

With all of the 55gr Gold Dot so readily available, I decided to perform a comprehensive test on it to determine its viability. I chronographed 60 rounds of it. All groups shot were chronographed, although targets and data were not linked. That data directly follows:

16.1" DDM4, CHF barrel, Chrome lined, approximately 5,000 rounds through it. Unless otherwise noted, Surefire 556-212 suppressor is present for all testing.
Chronograph at 10' from muzzle unless otherwise noted.

Shot string #1
2960
3019
2981
3004
3012
2004
2991
3002
3019
3022
AVG: 3001.4

Shot String #2 (unsuppressed)
3005
3011
3015
2979
2998
2965
2986
2987
2966
3011
AVG: 2992.3

Shot String #3
3005
3020
3034
2992
3010
3011
2982
3021
3041
3051
AVG: 3016.7

Shot String #4
3002
3003
3011
3005
3008
3027
3033
3001
3014
3032
AVG: 3013.6


100 yard chronograph placement, Shot String #5:
2534
2523
2551
2541
2529
2545
2513
2559
2537
2538
AVG: 2536

100 yard chronograph placement, Shot String #5:
2521
2552
2562
2524
2524
2559
2553
2545
2565
2547
AVG: 2545.2

The groups fired measure:

1.73" CTC
1.935" CTC
1.635" CTC
1.785" CTC
2.145" CTC
2.345' CTC (*last group fired, fired hastily after jogging back from the 100 yard line. This group was video'ed and you can see the split times between shots are not conducive to precision. It was also fired on a target which I had not taken a sharpie to, to help stand out better under 4x magnification, and is more indicative of shortcomings of the shooter vs. the weapon system.)

Average Group Size, accounting for ZERO fliers or shooter errors: 1.929"

Rifle used is as described above, optic used was a nightforce 1-4 FC-2 reticle. Rifle was rested on a hard sand-bag under the fore-end, with the buttstock freefloated/resting against the shoulder. Groups fired from seated at a bench.

100 yard Chronograph videos:
http://www.youtube.com/watch?v=pjZSbn7iHV4
http://www.youtube.com/watch?v=sJRK72d3YVs


Ballistic Coefficient is stated as .222, but regressing my 100 yard velocities shows a BC of 0.190. However, if tested over 2-400 yards distance, this may well change, as I have seen before people regressing 100 yard velocities to find BC, later taking the test to 200+ and the BC "rising", so take this with a grain of salt. That said, at 100 yards, that's what she's clocking.

Also tested was expansion and penetration in water-filled milk-jugs spaced 2" apart from each other. A total of 2 jugs were penedtrated through/through, with the first jug being blown wide floppy open. The second jug had a nasty ragged hole through/through, and the 3rd jug had a ragged entry hole, and no sign of trauma to the far wall. The impact distance was 50 yards from the muzzle, and calculated to be at 2705fps +-50, although the chronograph was not in play for that shot. The expanded slug measures 0.590" across it's widest petal span, and 0.354" between the petals at its narrowest, for an average expanded diameter of 0.472". 2 unfired projectiles were found to weigh 55.1gr, and this expanded projectile was found to weigh 41.8gr. for a total projected loss of 13.3gr and a retained weight of 75.8%. It is pictured below:


http://i65.tinypic.com/zskcbl.jpg
http://i65.tinypic.com/3588g92.jpg
http://i64.tinypic.com/2198keh.jpg

[Unobtanium]

Dr. Roberts, how fast were the 5.56 55gr (24455) Gold Dots moving from a 16" gun? I was expecting 2800-2850 from these, but they felt stout and the chrono pegs them at averaging a HAIR over 3,000fps. That's mild 5.56 territory based on other chronograph data of various M193 loads I've seen, no?

[DAVIDF]

Great info, thank you. I just purchased 800 rounds at some great prices. Is the POI much different than with M193?

[blues]

I purchased a bunch of this ammo as well as the 64gr version some months ago at deep discount with free shipping. Seemed the right thing to do at the time and nothing has made me regret that decision. In fact, I probably should have purchased more.

[Unobtanium]

Learned a little more. Apparently the 55gr stuff is loaded hot compared to other weights of gold dot. This is because homeland security was a huge buyer of the 24446 loading,and spec'ed a velocity very near 5.56.

[blues]

Learned a little more. Apparently the 55gr stuff is loaded hot compared to other weights of gold dot. This is because homeland security was a huge buyer of the 24446 loading,and spec'ed a velocity very near 5.56.

If I recall correctly, I believe ICE was the specific agency but I won't swear to it.

[Sixgun_Symphony]

Learned a little more. Apparently the 55gr stuff is loaded hot compared to other weights of gold dot. This is because homeland security was a huge buyer of the 24446 loading,and spec'ed a velocity very near 5.56.

But I thought it was the 64/62gr bullet loaded near 5.56 pressures?

[vicious_cb]

If I recall correctly, I believe ICE was the specific agency but I won't swear to it.

ICE spec'd the 64gr gold dot in non-nickle plated brass. I still have some that I brought back in 2010, from what I recall they were loaded to the same velocity as the regular nickle plated stuff. There was also a 5.56 55gr Gold Dot load that was discontinued.

[blues]

ICE spec'd the 64gr gold dot in non-nickle plated brass. I still have some that I brought back in 2010, from what I recall they were loaded to the same velocity as the regular nickle plated stuff. There was also a 5.56 55gr Gold Dot load that was discontinued.

Thanks. I knew I read about it somewhere but couldn't recall specifics. I actually have both rounds in .223 but more of the 64gr than the 55gr.

[Chuck Haggard]

For many users a warmish 55gr might be the best choice. Lots of 1033 program M16s and self bought hobby grade guns floating around in cop cars.

The M16s like warm ammo and 55gr bullets really well, hobby guns tend to choke or break on 5.56 spec ammo.

[LSW]

with the 75gr .223 gold dot ammo I'm getting 2230 fps out of a 10.5" (w/ suppressor) and 2450 out of a 14.5" (unsuppressed), both at 500 ft MSL elevation, 60 degrees Fahrenheit, approximately standard barometric pressure, CED M2 chrono.

Is 2230 fps still within the velocity threshold for satisfactory terminal performance on the 75 gr projectile? Mk262, my previous choice in defensive ammo is about 175 fps faster out of the 14.5. POI between the two at 125 yards was pretty close, about 1 MOA lower POI for the gold dot vs 262. Accuracy was 2 MOA or less.

[Unobtanium]

2200 is well above.

[Wondering Beard]

Is 2230 fps still within the velocity threshold for satisfactory terminal performance on the 75 gr projectile? Mk262, my previous choice in defensive ammo is about 175 fps faster out of the 14.5.

Keep in mind that the Gold Dot is a .223 while Mk262 is 5.56.

[LSW]

Thanks, just checking. I have read that 1800 fps is roughly the expansion floor for the 75 gr gold dot, which would put my effective range at about 200 yards. That would be good enough for a CQB oriented SBR for sure.

[Buckshot]

There was also a 5.56 55gr Gold Dot load that was discontinued.

DAMN! there goes my carry load!