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Asa Yam":2c1p4oic said:For 300-600 yards, 77 grain HPBTs work fine for magazine length projectiles.
For 300 to 900 yards, 80 grain HPBTs work. Even at 1000, it is possible to get accuracy, despite the projectiles being subsonic.
The 90s from JLK and Sierra need special twists (7 for the Sierra - not so bad. JLKs need 6.5" twists), different powders (RE15, N540 and 550)and lots of brass (loads get pretty warm - cases may be tossed after one firing) for performance at 1000 yards. On the other hand, a warmish 90 grain load will remain supersonic @ 1000 yards, whereas anything short of a really hot 80 grain load won't.
If you plan on building an 80+ grain projectile, the following criteria must apply:
- Thick jacket. A standard J4 jacket for .22 projectiles is too thin (and to short). Projectiles will fail in flight. Jimmy Knox (JLK) uses a 6mm jacket on his 90s for this reason;
- Projectile performance must be consistent between batches. Nothing kills your reputation faster than a bad batch of bullets, or an inconsistent product;
- Good accuracy. Don't bother selling projectiles to competitors if they don't group consistently within a production lot. Or between batches. Longer (heavier) projectiles are more difficult to get to shoot properly because the aerodynamic and mass centers are further apart;
- Explicitly state the twist rate needed to stabilize the projectile. As mentioned faster twists are needed with the longer projectile.
- Due to the proliferation of chamber profiles available, if you produce the projectile, you also must specify chamber/throat dimensions with the load data. 90 Grain loads generally need to be seated longer to maximize powder capacity, and to avoid damage to the projectile base on firing. Most .223 reamers will not allow a 90 to be loaded and still shoot accurately.
Extra mass alone is not sufficient to improve projectile performance (it helps some). Projectile form may also be different. Depending on aerodynamics, a secant nose profile may be a better choice than a tangent one. And BC values alone do not tell the whole story behind projectile behavior. A high BC may be impressive, but it doesn't do beans if the projectile simply refuses to group well because of inherent design deficiencies.
KJD,kjd":293hpv0i said:Actually your post is very specific to 223 shooters.. I know someone who shoots F class with a 22-250 AI and uses 80grain projectiles which are well and truely still supersonic at 1000m. I am sure he is not the only one that shoots long range with a 22 other then a 223.
The reason to go to a 90 is very cartridge and distance specific. Beyond 900 yards, a .223 Remington with 80s cannot reliably keep the projectile supersonic with loads that do not exceed SAAMI maximums, especially when using 20" long AR15 barrels. Going to a heavier projectile gives you an increased BC which (hopefully) delays the subsonic transistion beyond 1000 yards. It also gives you less wind drift. However, going to a 90 requires a large number of compromises, which many shooters are currently unwilling to make. Part of this is due to a limited knowledge base on how to build a suitable package of rifle and ammunition. Part of this is a lack of ranges, or the unwillingness of shooters to shoot at longer ranges. A very large reason is because "nobody else is using them" - this is because the bullets currently just aren't available.Is there a reason to shoot heavier than 77 & 80 grains?
Your lack of participation in NRA 1000 yard highpower matches is evident. AR-15s and M16s have been successfully used for 1000 yard competition for many years. While doing so obviously places the shooter at a slight disadvantage (compared to a shooter using a cartridge and rifle giving better ballistic performance), it's still the skill of the shooter that makes a significant difference.Sharpsman":3a0ci7te said:Couldn't help but sit here and shake my head while reading about the .223 round being seriously considered by some for shooting at 1000 yds.!...
Asa Yam":2jk52qoi said:Your lack of participation in NRA 1000 yard highpower matches is evident. AR-15s and M16s have been successfully used for 1000 yard competition for many years. While doing so obviously places the shooter at a slight disadvantage (compared to a shooter using a cartridge and rifle giving better ballistic performance), it's still the skill of the shooter that makes a significant difference.Sharpsman":2jk52qoi said:Couldn't help but sit here and shake my head while reading about the .223 round being seriously considered by some for shooting at 1000 yds.!...
I've shot a .223 in competition at 1000 yards, and have finished quite high in the fiinal standings. Did I have to work harder than the competition? Yes. But the difference in windage wasn't much, compared to a 155 grain .30 caliber projectile, traveling at 2950 FPS.
I don't fully agree with this assessment.Sharpsman":14627muo said:And....there's a vast world of difference in the accuracy potential of a 'worked over' M-16 and the rifle that's issued to the frontline troops!!
I, and many others, DO NOT SHARE your opinion.IMO....it's still a piece of JUNK for a Service Rifle...
Somewhat successful? Really?...and the ONLY REASON it's been somewhat successful in competition...
...is because IT IS THE CURRENT SERVICE RIFLE and the Service Teams are REQUIRED to shoot it!!
Oh, I've read the reports.Sharpsman":2tznl6gg said:Asa Yam
You have your opinions.....I HAVE MINE!
You won't change MY OPINION.....that the M16 is still A PIECE OF JUNK!!
It's also quite obvious......that you haven't read any reports/critiques from frontline troops whom 'lamblast' the performance of the rifle.....and the cartridge from some "Gunnys"....one in particular from a Sgt. Major within the USMC!! This report/critique was so unique that it found it's way to the Commandant of the USMC! If I had saved that documnet I'd post it here but save it I didn't!
5.56mm “definitely answered the mail” and “as long as the shots were in the head or chest they went down” were typical quotes from several Marines; many who were previously very skeptical of 5.56mm ammunition. (Emphasis mine - Asa.) Most of the interviewed Marines who reported targets not going down and/or could still fight were referencing non-lethal shots to the extremities. There were reports of targets receiving shots in the vitals and not going down. These stories need not be described, but are of the rare superhuman occurrences that defy logic and caliber of round." (Emphasis mine.)
M4: Soldiers were very satisfied with this weapon. It performed well in a demanding environment (Emphasis mine)especially given the rail system and accompanying sensors and optics. As one Brigade Commander said “The M4 with PEQ and PAC provided overmatch over our threat equipped with AK47s and RPGs.” The general consensus is that every rifleman wants the M4 vice the M16A2.
AndSection I. M16 Series of Assault Weapons, 5.56mm Ammunition, and Accessories
General discussion:
The US Army executed OIF with three variants of the M16 series of assault weapons: the M16A2, the M16A4, and the M4 Carbine (hereafter referred to as M16 series). The latter two were configured as Modular Weapon Systems in units so equipped. A fourth version, the M4A1, was used by Special Operations Forces but was not encountered by the assessment team.
The M16 series received widespread praise for its durability and reliability. (Emphasis mine.) A few soldiers expressed a desire to be able to fire the weapon after pulling it out of the dirt (“like you can do with the AK” was the perception), but there were no trends of poor reliability. This may be attributed in part to the ease of maintenance reported by the soldiers. While keeping the weapons clean in this environment was a continuous requirement it was not considered to be a difficult one.
Most soldiers considered The M16 series to be very accurate regardless of the version used or the sighting system employed. One sniper team spotter employed his M16A4 (equipped with a high powered scope) against targets at 600 and 800 meters with first round hits in each case. (Emphasis mine.)
Those units equipped with the Rail Adapter System (RAS) were very happy with its modularity and flexibility of employment. Most units allowed soldiers to place accessories on the Modular Weapon System where they best suited the individual. Some units prescribed weapon configuration in their standard operating procedures. Many soldiers stated that the RAS should be an integral part of the weapon rather than an adapter kit.
In the discussion with field units there were no quality issues with ammunition from the production facility. Consensus of the troops is that this weapon/ammunition is effective for its intended purposes. Ammunition was correctly marked and packaged and there were no incidents of defective materials, damaged or dented rounds etc.
And finally...Operational Suitability:
The Iraqi desert was very challenging and harsh, but the current weapons, ammunition and accessories the soldiers took to battle functioned, withstood the elements and were lethal. The weapons that stood-out were the M2 HMG, M240B MMG and the M4 MWS. The M2 HMG and M240B MMG were praised mostly for their ruggedness and reliability. The weapon’s reliability was most important to the soldiers. (Emphasis mine.) The M4 MWS’ modularity, size and weight was well received by soldiers issued this weapon system. It enabled soldiers to conduct clearing operations in urban terrain and easily transition from day to night operations.
Although the M4 MWS was reliable, the team observed light primer indentation occurrences in the M16 series rifles: M4s and M16s. As soldiers locked, loaded and cleared weapons prior to and after operations or as directed, the primer was indented. Upon return to CONUS discussions with weapons engineers revealed that each time a cartridge is chambered in an M16 Series Rifle or M4 Series Carbine, a slight indentation is made on the primer. This is caused by contact of the free-floating firing pin against the cartridge primer as the bolt closes. This is a function associated with normal operation of the weapon. The Army conducted tests to investigate the effects of multiple detents on 5.56mm ammunition. No slam fire, or accidental discharges occurred.
However, cartridges are not intended to be repeatedly re-chambered as this may de-sensitize the primer and/or deform the body of the cartridge case sufficiently to cause misfires. The potential for a misfire may occur in as few as 10 to 20 lock and load cycles of the same cartridge. No misfire occurrences were directly observed from indentations but soldiers relayed some occurrences of accidental discharges when going through the clearing procedures and one soldier experienced a misfire – from a round cycled through the chamber numerous times. Further testing is planned to more accurately quantify these conditions and establish the need of a Maintenance Advisory Message (MAM).
As stated above, soldiers rank reliability and durability as key weapon characteristics and are not willing to trade them for anything – to include weight. Similarly, soldiers do not consider the weapon as part of their load, but rather as an enabler. They are willing to carry the weight if the weapon or device increases his lethality. This is best illustrated by soldiers purchasing their own magnified optics and the strong desire to carry an additional sidearm or shotgun for defensive and offensive purposes. Lethality is more important to the soldier than any other consideration or factor.
Lethality:
It is apparent that the close range lethality deficiency of the 5.56mm (M855) is more a matter of perception rather than fact, but there were some exceptions. The majority of the soldiers interviewed that voiced or desired “better knock-down power” or a larger caliber bullet did not have actual close engagements. (Emphasis mine.) Those that had close engagements and applied Close Quarters Battle (CQB) tactics, techniques, and procedures (TTPs) – controlled pairs in the lethal areas: chest and head and good shot placement, defeated the target without issue. Most that had to engage a target repeatedly remarked that they hit the target in non-vital areas such as the extremities. Some targets were reportedly hit in the chest numerous times, but required at least one shot to the head to defeat it. No lethality issues were voiced with targets engaged at 200 meters and beyond. It is apparent that with proper shot placement and marksmanship training, the M855 ammunition is lethal in close and long range.
From http://www.odcmp.org/new_forum/topic.as ... hichpage=3What I'm wondering is.....how well you'd like/love it....if your boots were on the ground in Iraq/Afghanistan...
The author of the above is a Green Beret LTC. Who also happens to be an avid rifle competitor (he's Distinguished), and the former Commanding Officer of the AMU.The last time I faced bad guys was in 2003 on an airfield in western Iraq, armed with an M4. I would much rather have had a full-length M16 to go with the 400 rounds of 5.56 I was carrying, to dominate everything i could see out to 500. I could NOT have carried that equivalent load in 7.62 for the weight. I have full confidence in my ability to kill a target to 500 yards with a base iron sight M16.
Yeah, right. Appendix C of "Weapons Effects and Employment in an Urban Environment, by Tactics Group, The Basic School (USMC), MCCDC, Quantico, Va." ( http://www.globalsecurity.org/military/ ... ppendc.htm ) has this to say about 5.56mm and 7.62 NATO performance against a 12 inch cinder block, filled with sand:...maybe trying to put some rounds through a cinder-block wall....which is by reports a totally useless effort.....while you would be watching insurgents putting their rounds from an AK-47 through the same type wall as if it were 'hot butter'!!
As shown above, troops currently in the field largely agree the M16 is both reliable and lethal. And if you are familiar with operating the rifle on the range, running one on the battlefield becomes less of a challenge.There's a helluva lot of difference between a competitive rifle match where everything is nice and clean and a combat zone that's filled with smoke, grim, crud galore, and not knowing whether your 'piss ant' rifle is going to operate when needed....or not!!