What grain bullet any why

[Bloodknight]

Since there is a wealth of knowledge on this site. Thought I would use it.First,We use the 7.62 round while I served in the Marines. Who knows what grain was used and why was that particular amount chosen? Second, what grain is the military with the 5,56 using today and why ? Any info on the habits of certain grains of ammo would be appreciated.I have been useing Hornaday 5,56x75 black. Which now seems difficult to find, I got an email from a place that claimed to have some. But it turned out to be a scam

 

[Bassbob]

As of a couple years ago it was still M193 and M855A.

 

[HansGruber]

Since there is a wealth of knowledge on this site. Thought I would use it.First,We use the 7.62 round while I served in the Marines. Who knows what grain was used and why was that particular amount chosen? Second, what grain is the military with the 5,56 using today and why ? Any info on the habits of certain grains of ammo would be appreciated.I have been useing Hornaday 5,56x75 black. Which now seems difficult to find, I got an email from a place that claimed to have some. But it turned out to be a scam

First off: grain is a measurement of weight. Saying “what grain bullet” makes as much sense as saying “what ounce steak”.

The US 7.62x51 was 147grfmj; basically because it was nearly ballistically identical to the M2Ball .30-06 round.

Currently, most of the military is using the 62grM855/M855A1. The Air Force still was using 55gr M193 the last time I checked.

As to what to use? Whatever your rifle likes. Twist rate and barrel length can both play a factor, so….google is your friend.

 

[Snake45]

As to what to use? Whatever your rifle likes. Twist rate and barrel length can both play a factor, so….google is your friend.

I'd start with what you want to DO with the rifle--hunting, home defense, competitive target shooting, long range, plinking, other? This might well lead you to a bullet weight range, and then you can begin narrowing down specific bullet types, brands, and so forth.

 

[ECS686]

I run old 55 gr FMJ. If I needed to buy more or so Anything special I’d probably use the Federal 62 gr Tactical Bonded that the FBI has went to recently

Back when I was working we did some interagency stuff with FBI SWAT out of Saint Louis and Springfield. In 2009 era they had ditched the MP 5’s and went to M4 and 55 grain FMJ for building entries. The standard 55 grain FMJ didn’t over penetrate as some believed so if that’s what you got I wouldn’t worry too much!

 

[TEXASforLIFE]

I choose bullet weight by use/barrel length/purpose. All dictated by 5.56 to 45-70. In 5.56 @ 11.5" will be 55gr, 16-20" @ 62gr and 24" @ 75gr. For 308win, @ 12.5" will be 110-135gr, 18-22" (except m118 chamber) @ 150-170gr and 24"+ will be 170-195gr. I don't have any suppressors, so no sub ammo. The 12.5" using 147gr kicks very hard (weight is around 10#). If I were to run an sbr instead of a pistol it would be more manageable.

 

[KillerFord1977]

I choose bullet weight by use/barrel length/purpose. All dictated by 5.56 to 45-70. In 5.56 @ 11.5" will be 55gr, 16-20" @ 62gr and 24" @ 75gr. For 308win, @ 12.5" will be 110-135gr, 18-22" (except m118 chamber) @ 150-170gr and 24"+ will be 170-195gr. I don't have any suppressors, so no sub ammo. The 12.5" using 147gr kicks very hard (weight is around 10#). If I were to run an sbr instead of a pistol it would be more manageable.

Agreed

My SBR(nfa stamped) in 10.5” barrel suppressed runs 77gr very accurate.

55-62 gr ammo give me 4-6” groups
Anything less than the 69 gr ammo in .223 or 5.56 just opens the pattern up

 

[HayesGreener]

I use 77 gr in my Sig 516 because the barrel likes it. The last time I qualified with an M4 it was 55gr. The barrel twist and length on my 516 is different than in an M4 and that makes a difference.

 

[Talyn]

55 gr. M193 is still used by the entire US military for training since its cheaper.

As others have said choosing 5.56/.223 (but really any cartridge) bullet weight is based on intended use/purpose. As others have said twist rate is a key factor. Heavier (therefore longer) bullets require a faster twist rate to stabilize the bullet until it slows enough down-range to destabilize. But barrel length is also a factor with shorter barrel lengths typically result in lower initial velocities which results in a shorter de-stabilization range.

The US military chose the 62 gr. weight to add range & lethality with the M16A2 model, and standardized the 1:7 twist range on the M855/M855A1/SS109 spec-loads, although the 1:7 twist rate was needed stabilize the longer/heavier NATO L110/M856 5.56×45mm NATO tracer bullet.

The M855/M855A1/SS109 was developed to meet a NATO requirement that the bullet be able to penetrate through one side of a WWII U.S. M1 helmet at 800 meters (which was also the requirement for the 7.62×51mm NATO). The intention was that the 62 gr full metal jacket bullet, with a mild steel tip, moved the center of gravity rearward, increasing flight stability and thereby the chances of striking the target tip-first at longer ranges.

However, there have been terminal performance deficiencies with the M855/M855A1/SS109 during its use in overseas conflicts. These problems have primarily been manifested as inadequate incapacitation of enemy forces despite their being hit multiple times by M855 bullets. These failures appear to be associated with the bullets exiting the body of the enemy soldier without yawing or fragmenting.

Cost is also a actor. I use M193 55 gr-equivalent for 95% of range/training use, and don't se a need to use more expensive M855/SS109 for that purpose. While I have M855/SS109 use it with a commercial 64 gr. load that provides better terminal performance on soft-targets in a mixed self-defense loadout.

I max out with 75 gr loads for LR CMP competition stages.

My .02

 

[ddeuce22]

55 gr. M193 is still used by the entire US military for training since its cheaper.

As others have said choosing 5.56/.223 (but really any cartridge) bullet weight is based on intended use/purpose. As others have said twist rate is a key factor. Heavier (therefore longer) bullets require a faster twist rate to stabilize the bullet until it slows enough down-range to destabilize. But barrel length is also a factor with shorter barrel lengths typically result in lower initial velocities which results in a shorter de-stabilization range.

The US military chose the 62 gr. weight to add range & lethality with the M16A2 model, and standardized the 1:7 twist range on the M855/M855A1/SS109 spec-loads, although the 1:7 twist rate was needed stabilize the longer/heavier NATO L110/M856 5.56×45mm NATO tracer bullet.

The M855/M855A1/SS109 was developed to meet a NATO requirement that the bullet be able to penetrate through one side of a WWII U.S. M1 helmet at 800 meters (which was also the requirement for the 7.62×51mm NATO). The intention was that the 62 gr full metal jacket bullet, with a mild steel tip, moved the center of gravity rearward, increasing flight stability and thereby the chances of striking the target tip-first at longer ranges.

However, there have been terminal performance deficiencies with the M855/M855A1/SS109 during its use in overseas conflicts. These problems have primarily been manifested as inadequate incapacitation of enemy forces despite their being hit multiple times by M855 bullets. These failures appear to be associated with the bullets exiting the body of the enemy soldier without yawing or fragmenting.

Cost is also a actor. I use M193 55 gr-equivalent for 95% of range/training use, and don't se a need to use more expensive M855/SS109 for that purpose. While I have M855/SS109 use it with a commercial 64 gr. load that provides better terminal performance on soft-targets in a mixed self-defense loadout.

I max out with 75 gr loads for LR CMP competition stages.

My .02

Hot damn this was a good ass diatribe. Good work brother.

 

[Talyn]

Hot damn this was a good ass diatribe. Good work brother.

I see some typos but I can't fix them now.

Hope it helps the OP & others that are new to ARs and other rifles.

 

[TEXASforLIFE]

55 gr. M193 is still used by the entire US military for training since its cheaper.

As others have said choosing 5.56/.223 (but really any cartridge) bullet weight is based on intended use/purpose. As others have said twist rate is a key factor. Heavier (therefore longer) bullets require a faster twist rate to stabilize the bullet until it slows enough down-range to destabilize. But barrel length is also a factor with shorter barrel lengths typically result in lower initial velocities which results in a shorter de-stabilization range.

The US military chose the 62 gr. weight to add range & lethality with the M16A2 model, and standardized the 1:7 twist range on the M855/M855A1/SS109 spec-loads, although the 1:7 twist rate was needed stabilize the longer/heavier NATO L110/M856 5.56×45mm NATO tracer bullet.

The M855/M855A1/SS109 was developed to meet a NATO requirement that the bullet be able to penetrate through one side of a WWII U.S. M1 helmet at 800 meters (which was also the requirement for the 7.62×51mm NATO). The intention was that the 62 gr full metal jacket bullet, with a mild steel tip, moved the center of gravity rearward, increasing flight stability and thereby the chances of striking the target tip-first at longer ranges.

However, there have been terminal performance deficiencies with the M855/M855A1/SS109 during its use in overseas conflicts. These problems have primarily been manifested as inadequate incapacitation of enemy forces despite their being hit multiple times by M855 bullets. These failures appear to be associated with the bullets exiting the body of the enemy soldier without yawing or fragmenting.

Cost is also a actor. I use M193 55 gr-equivalent for 95% of range/training use, and don't se a need to use more expensive M855/SS109 for that purpose. While I have M855/SS109 use it with a commercial 64 gr. load that provides better terminal performance on soft-targets in a mixed self-defense loadout.

I max out with 75 gr loads for LR CMP competition stages.

My .02

The issue with the 64gr tracer is it requires the 7 over the 8 twist due to not lighting up the paint that an 8 twist fails to do. It's not as much about velocity as twist is. The 62gr lap round will stabilize in an 8 and a 9 twist, but as you stated the down range plays a factor when speed is lost and will start to destabilize. Even with the 7 twist 20" barrel I have the paint doesn't always light up. I believe it's more of a failure on the application than the twist or velocity. I don't have any 9 twist, but do have 8's that'll light it up as much as the 7's do.