Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Ballistic Rapid-Fire Questions

  1. #1
    Join Date
    Aug 2016
    Posts
    315
    Feedback Score
    0

    Ballistic Rapid-Fire Questions

    Hi, these have been accumulating in my brain for a while now and I thought it would be easier if I just asked all of them in one post, since they are related and follow a common theme. Any information on them would be much appreciated.

    1. What is the current gold standard for best civilian-legal defensive ammo? Last I checked, Doc was saying that the Black Hills reinforced 50 gr TSX was the cream of the crop. Has this theory changed at all?

    2. Which AR-15 compatible bullet has the shortest ballistic wound neck? The best that I have seen tested is the Sierra 77 TMK, which started fragmenting almost instantaneously in gel. This seemed to be one of the major grievances of M855, so I'm just curious how much the science has developed since its introduction.

    3. Has the military stopped using "Brown Tip" ammunition, which was rumored to be 70 TSX loads? When would a round like this be preferred over M855A1 or Mk262?

    4. What is the lowest expansion velocity threshold for any bullet that's compatible with the AR-15? I remember seeing a Lehigh .300 BLK all-copper round that they claimed broke apart down to 1400 FPS. 70 TSX apparently goes down to 1800 FPS. Is that about as good as it gets?

    5. In a combat situation, what is the most optimal 5.56 barrel length for an unknown theater? I know that John Noveske claimed that 12.5" was the most optimal, and the military seems to be happy with 14.5" after all these years. I would think that as short as you could get while still utilizing a midlength gas system would probably cover your bases for most situations. How often are infantry engaging the enemy at extended ranges anymore?

    That's it for now, thanks in advance

  2. #2
    Join Date
    Mar 2011
    Location
    Mid-West, USA
    Posts
    1,757
    Feedback Score
    37 (100%)
    Concerning point 5, John Noveske's 12.5 polygonal rifles barrels were giving the velocity of the military's 14.5.
    Last edited by taekwondopreacher; 11-26-19 at 22:33. Reason: Addressed wrong point.

  3. #3
    Join Date
    Aug 2017
    Location
    Lowcountry, SC.
    Posts
    1,693
    Feedback Score
    3 (100%)
    1) depends. Top ranked loads include in no particular order: 77TMK from Black Hills, Fusion MSR 62gr, Gold Dot 75gr, Barnes 70gr, Federal FBI T3, Ranger Bonded 64gr, and Barnes 50gr. I would suggest doing a Google search of those to start, and then choose how deep down the rabbit hole you wish to go. My HD mags have Fusion MSR in them; you might arrive at a different conclusion.

    2) If I remember correctly, the shortest necks I have seen in amateur videos has been the 77TMK and the Gold Dot 75gr. No neck. All of the loads I listed in (1) have acceptably short necks. Nothing like M855. Andrew at The Chopping Block youtube channel does tests of most available AR ammo, and appears to do so reasonably well, but with small sample sizes.

    3) Fusion 62gr expands to 190% at 1700fps. No idea what it does at less than that. There are several other loads that will work at 1800-2000, such as the 77gr TMK, any of the Gold Dots, and at least some of the TSX’s.

    5) I’m not sure anyone, including the .Mil has a perfect answer for this. I suspect that with 5.56, its somewhere on the spectrum of 12.5”-16” and suppressors, optics, training, and tactics can invalidate that answer. I’ve arrived at the conclusion that 16” would actually work pretty well for a general issue infantry carbine. Then again, so does a 14.5”.
    RLTW

    “That is why there isn't an AK chart.” -SteyrAUG
    “They eat tide pods also so what's your point?” Retrorevolver77

  4. #4
    Join Date
    Aug 2011
    Location
    N.E. OH
    Posts
    6,180
    Feedback Score
    0
    1: i think 50g tsx (bh) or tbbc. He has often stated he would take anything on his list without hesitation, but those seemed to be his standards

    2: dont know, but good soft points open up consistently faster than fragmenting rounds(frag rounds may frag quicker occasionally, but not consistently, and its different for each barrel- speaking about yaw-required frag rounds like greentip). Tipped rounds like you reference open up fast but not sure of the penetration- its usually too low, but the specific load you mention may be an outlier. Barrier performance would be a question for me as well with that.

    4: fusion 62 expands down to 1300. It would retain velocity to a further distance than 300, so you need to look at each load independantly to make use of the data, unless you are doing handloads or wildcat stuff.

    5: probably going to get the gamut here- I think 12-14 is the best balance for 556/545, but i dont combat. That range is compact enough to be easy to use inside, even with a silencer, and long enough to reach well past - almost double - the “300yd” standard... but then optics and training have to be there as well.

    Disclaimer- most of this is gathered i formation from online (sme’s on this site mainly), from docgkr posts, and a little hands on with 14.5, 16, and 11.5” ARs. My opinion on barrel length needs to be taken lightly as my overall experience is pretty limited.
    Last edited by MegademiC; 11-26-19 at 20:47.

  5. #5
    Join Date
    Aug 2017
    Location
    Lowcountry, SC.
    Posts
    1,693
    Feedback Score
    3 (100%)
    Megademic,

    1) If I remember correctly, one of the reasons he recommended 50 TSX was cops with slower twist rates, such as 1:9, or worse. Not that I’m saying it isn’t an excellent choice. For example A have a cop buddy in a medium sized city that is a $*!*hole. Last year his department bought them surplus M16a1 uppers. WTF are they supposed to feed those things? A good bandaid for this poor barrel selection would be 50TSX or 55 Gold Dot, although I bet if I ask him it will be some dumbass varmint projectile.

    2) the 75 and 77 grain match bullets, including TMK have a good reputation for adequate penetration unless an intermediate barrier is involved. 68 and 69 grain match bullets are the ones that come up short.

    5) as far as reaching out to double the 300 yd “standard” goes, we have to get the combination of weapon, shooter, and ammo to shoot x moa to hit x sized target at x range after detecting a target, estimating range and wind, and gaining a position and sight picture. The group/zero target at 25m pretty much sets the “standard” for marksmanship in the Army loosely at around 6moa, same as the E-Type target at 300m. Dude is not actually required to hit the 300. The E-Type, is of course the form factor of a human standing in the open, which in and of itself is not entirely realistic. But, assuming enemy in the open, standing still, a shooter that can do the above things like estimate range, and hold a better than average moa can eventually get hits to 600m with fairly light training.

    However, I’m of the belief that 200-300 yds is the max an individual Infantryman is likely to get easy hits, and even that is a stretch depending on terrain and the enemy’s cover and movement. I’m not convinced the “Infantry Half Kilometer” has ever REALLY been a thing for the average individual rifleman, so much as have a bunch of dudes launch a bunch of bullets. If a dude can consistently hit an E-Type 500 yds on a KD range with a basic bitch gun and ammo, he might be a good candidate for a DMR and some additional training.

    Ballistically, 200-300m first round hits on E-Types, if that is the standard, is easy peasy with a 12.5” barrel. Of course there are other factors, such as flash, noise, penetration at range, idiots shooting their own cover/concealment, etc.
    RLTW

    “That is why there isn't an AK chart.” -SteyrAUG
    “They eat tide pods also so what's your point?” Retrorevolver77

  6. #6
    Join Date
    Sep 2008
    Posts
    1,109
    Feedback Score
    3 (100%)
    Bullets are bullets. Shoot 55 grain 5.56 or SAAMI spec. Everything else is just marketing.

  7. #7
    Join Date
    Dec 2009
    Location
    Florida Gulf Coast
    Posts
    1,424
    Feedback Score
    5 (100%)
    Good shot placement, after that don't put too much thought into it. Common sense dictates everything else.

  8. #8
    Join Date
    Jun 2009
    Location
    AZ
    Posts
    5,270
    Feedback Score
    6 (100%)
    I load my guns with what I train with being 77grain SMK's. Mr. Goodtimes pretty much summed it up. I have a hard time thinking a civilian like myself is going to shoot past 50 yards in most situations. And that gun and ammo is going to kill them very very dead.

    I like a 10.3 Colt 6945 for my HD gun. Sig 556 can and a 20 round mag.

    PB
    "Air Force / Policeman / Fireman / Man of God / Friend of mine / R.I.P. Steve Lamy"

  9. #9
    Join Date
    Nov 2016
    Posts
    11
    Feedback Score
    0
    1. BH 50 gr TSX is good, but has poor steel performance. It also has a greatly reduced expansion range compared to many bonded soft point loads due to a higher expansion threshold and a lower ballistic coefficient. The upside of it is that it works in lower twist barrels and might potentially produce greater wounding at closer ranges, as it achieves a similar degree of expansion with higher velocity.

    My personal preference would be Black Hills 77 gr TMK, as it achieves maximal terminal performance in soft tissue while also expanding likely at least as reliably as a bonded soft point. The downside is that it is not barrier blind, but likely does have better barrier performance compared to most traditional OTMs.

    Other top tier loadings are 62 gr/64 gr Fusion/Gold Dot, 62 gr TBBC, and 64 gr RA556B.

    2. 77 gr TMK has an extremely short neck, but there are other projectiles that have necks that are similar or possibly even a bit shorter, e.g. 62 gr TBBC. In practice it would be splitting hairs, as a ~0.5" neck length is already short enough for pretty much any purpose other than maybe tiny varmints.

    As mentioned, heavyweight fragmenting rounds usually have adequate penetration out of the common defensive barrel lengths. With longer barrels (18+) their performance may become suspect.

    3. I have no idea if the military still uses 70 gr TSX, but generally speaking this type of round would be preferred over Mk262 in cases where barrier penetration and performance is more important. It is not quite as barrier blind as the Black Hills exclusive 50 gr TSX, but does do better than 77gr SMK, and also has a much longer expansion range. (Given the military's seeming focus on mechanical precision over terminal performance for long range use however I suspect they would still tend to use Mk262 for that purpose, IMO perhaps unwisely.)

    Compared to M855A1 I am not sure that it really does anything significantly better in an antipersonnel role, other than possibly having better long range external ballistics. 70 gr TSX doesn't wear out feed ramps but this is not an issue regardless with readily available EPMs and Gen 3 PMAGs.

    4. I haven't seen a lot of testing done at extremely low velocities, so it's hard to know exactly which bullet has the lowest expansion velocity. Fusion/Gold Dot does still expand at 1700 FPS as noted previously, although based on the appearance of the bullet it's close to riding the edge at that point. 77 gr TMK reportedly also expands below 1800 FPS. Based on the performance of M80A1, M855A1 probably frags below 1800.

    5. I have no military experience and can't speak as to ergonomics, but from a terminal standpoint, a 16" barrel works well with most ammunition choices. Longer barrels sometimes underpenetrate with thinly jacketed fragmenting rounds, while shorter barrels will get less range and disruption. In practice, not much difference between a 14.5 and 16, of course. But a 16" does seem to be easier to tune for reliability with a midlength gas system, at least from my very limited understanding.

  10. #10
    Join Date
    Aug 2016
    Posts
    315
    Feedback Score
    0
    Thank you everyone for your responses! This was very educational.

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •