House Rifle Ballistics

[cclaxton]

Are you using FMJ loads for home defense?

No. Speer Gold Dot LE softpoint 64gr..

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[Malamute]

No. Speer Gold Dot LE softpoint 64gr..

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Then is yaw and fragmenting from the yaw a factor if the bullet is an expanding type?

[cclaxton]

Then is yaw and fragmenting from the yaw a factor if the bullet is an expanding type?

My understanding is that yes they essentially are the same thing. However perhaps others here who have more experience on this topic could comment.

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[Malamute]

I believe the FMJ and expanding bullets behave differently at various velocities, but I'm interested to learn more about it if someone with more knowledge can comment. I was just looking for info on that particular bullet to see what Speer figures the velocity range is where it expands reliably. There wasnt anything on Speers site I could find. The first hints I found online indicated 1800 fps and 1600 fps, but they werent factory cited or have any specifics on why they knew that so I went on.

My experience shooting small game with 55 gr M-193 type loads was they were not consistent in how they behaved in cottontail and jack rabbits at closer range from a 20" barrel. Jacks would either be crunchy, or not, but almost never had a spectacular effect like a soft point. They also didnt always kill prairie dogs anything like soft points at 300 yards. Some prairie dogs would crawl back in their holes after a body hit with M-193 at 300 yards. 55 gr soft points were absolutely spectacular on cottontails (useless for meat hunting in that regard), as in they basically exploded. Jacks or coyotes would get about a 2" or so exit hole. Prairie dogs pretty well exploded at 300 yards.

I'm certain old school soft point bullets expand reliably at 300 yards in 223 loads (one could look up ballistics charts to see what velocity they had at that distance), as thats within the varmint role the older commercial loads were intended for, but todays bullets may be entirely different.

[StraitR]

My understanding is that yes they essentially are the same thing. However perhaps others here who have more experience on this topic could comment.

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Just to clarify, I am not an expert, and I learn more everyday, but I'll share a bit of what I know from my experience. I just took part in a ballistics gel test on Friday for a local SO, and we tested Hornady 55gr GMX (5.56), 64gr Win Ranger (5.56) and 62gr Gold Dot (223). We tested from 16", 10.5", and a 7" barrels (small local AR builder was trying to get their Swat into 7" guns - Yes, not a good idea, they knew that, but tested it anyway). Each of these rounds are designed to expand within certain velocity windows, not yaw and break, and none of them did so through either safety glass (FBI protocol) or bare gelatin out of any of those barrel lengths.

Contrary to popular belief, the slower these projectiles travel (like out of the 10.5/7" barrels), the higher the probability of failing to expand, causing them to yaw, flip 180 degrees, turn and exit the blocks (8x9x16" back to back blocks) or yaw, flip, and over-penetrate. They're simply not hitting the velocities in which they were designed to fully expand, and that is what makes them yaw, but none of them broke apart. XM193 is a completely different story, so if your after yaw and break, that's likely what you'll want to stick with. Any of the latest and greatest 5.56/223 SD/LE ammo is designed to expand and stop.

I work LE/Mil sales, and we submitted the Hornady product for this test. Due to the ongoing contractual bidding process, I'm not going to disclose the results of the other projectiles. I'll throw in some basic pics of the set-up and the Hornady GMX bullet. Gel was properly calibrated per FBI protocol. Shot with BB gun at 590fps (+/- 15fps) to depth of 2.94-3.75" with Gelatin temp at 39 degrees (+/- 2 degrees).

The SO was mostly concerned with safety glass data, which was the main driver and focus of the testing. The monolithic GMX projectile performed exceptionally well going 15.75" after safety glass and retained 77% of it's weight out of a 16" barrel. Same 16" barrel, it went 15.5" in bare gelatin and retained 100% of it's weight. The 10.5" barrel results were basically +2" (+/- .25") of penetration to the 16" results. That's a pretty good example of barrier blind, and also shows that when the projectile is slowed down (via both shorter barrel length and the safety glass) it didn't expand quite as much and ultimately penetrated just a bit more. If it were slowed too much, outside of it's design scope (such as the 7" barrel) it didn't expand enough, yawed, and over-penetrated ass first.




Hornady TAP GMX 55gr 5.56mm, 16" barrel, bare gelatin.

[DocGKR]

Good discussion above.

First, .224" FMJ's typically upset and yaw; they may also hyper-expand and fragment if traveling at higher velocities. On the other hand, .224" JHP & JSP bullets are designed to expand over a specified velocity range and generally do NOT yaw unless the velocity is too low to properly expand; if the velocity of the .224" JHP or JSP is higher than the specified engineering limits, the bullet can hyper-expand and fragment, reducing terminal effects.

The JSWB-IPT identified two issues that significantly alter projectile upset depth (neck-length or NL) at CQB distances, thus causing differing terminal effects.

First, Angle-of-Attack (AOA) variability at impact can substantially wound severity; this factor is more prevalent with certain calibers and projectile types. Testing demonstrated that 5.56 mm is highly susceptible to AOA variations, particularly when using FMJ projectiles such as M193 & M855. For example, with 5.56 mm FMJ, at higher AOA's, for example 2-3 degrees, bullets had a shorter neck length and upset rapidly, thus providing adequate terminal effects; at low AOA, like 0-1 degree, the projectiles penetrated deeper than ideal prior to initial upset (ie. long NL) with significantly reduced terminal effects. Note that other calibers were less susceptible to AOA variations than 5.56 mm and expanding projectiles tend to have less AOA issues than FMJ. The 6.8 mm has proved to have the least AOA inconsistencies of any caliber tested to date.

Fleet Yaw is the other significant yaw issue discovered by the JSWB-IPT. Fleet Yaw is the terminal performance variation caused by inherent variability in each rifle. 5.56 mm FMJ had the most Fleet Yaw induced variability of any projectile caliber & type. 6.8 mm had the least Fleet Yaw variations of any projectile caliber & type tested.

What this means is that two shooters firing the same lot of M193 or M855 from their M4's with identical shot placement can have dramatically different terminal performance results: one shooter states that his load is working great and is effective at dropping bad guys, while the other complains his opponent is not being incapacitated because the FMJ is zipping right through the target without upsetting. Both shooters are telling the truth. In addition, FMJ typically offer poor performance against automobile windshields.

For these reasons, .224" FMJ's are NOT recommended projectiles for LE and civilian defensive use, expanding barrier blind projectiles like GMX, TSX, Gold Dot, TBBC, CLUB, etc... are much better options.