308 vs. military surplus 762 x 51 in the H&R?

[littledog]

 After lots of reading on this forum and if I understand it right shooting military surplus 5.56 in a H&R 223 is not recommend because of over pressure . Is this the same for 308 vs. military surplus 762 x 51 in the H&R?

[Norminator]

My understanding is that it is the factory civilian rounds that may be too hot for the military rifles.

[Larry L]

Loads of misunderstanding about these two different cartridges. The reamer dimensions are different but they are so close that it generally doesn't matter. One side will tell you that military ammo is loaded to less pressure than 308. In most cases, this is correct, but not in all cases. Armor Piercing M993 ammo is loaded to 55,115 PSI which equals factory ammo as most factorys load 308 to 55,000PSI. Should you get your hands on some M60HPT ammo, it's loaded to 67,500PSI which is more than factory 308. Where it gets confusing is that military ammo is designed around a very specific burn rate and pressure build so that it has a predetermined pressure at the gas port on the automatic weapons. That means you'll be staying around the burn rate of WC846 or IMR4895. So is it safe in your H&R? If it's ball ammo, it's loaded to lighter pressures than factory 308. If it's M60HPT ammo, I probably would pass on pulling the trigger on it. SAAMI max pressure for the 308 is 62,000PSI but most factory ammo is 55,000PSI.
Confused yet?

[OldSchoolRanger]

The short answer is:

You can use 223 ammo in a rifle chambered for 223, and 5.56.
You should not use 5.56 ammo in a rifle chambered for 223.
You will also void any warranty you have on H&R guns if you use military (5.56) ammo.

You can use 7.62x51 ammo in a rifle chambered for 308.
You should not use 308 ammo in a rifle chambered for 7.62x51.

My recommendation is not to use 7.62x51 machine gun ammo in a rifle chambered for 308.  Besides possible pressure problems, I found it to be inaccurate.

[SHOOTALL]

With AR's vs M4/M16 keep in mind AR's in many cases have barrels that are rated at 10000 psi less strength than military barrels. It would be very hard to get a barrel that was true MIL. Surplus as they are shorter than 16 inch. And mil. spec. can mean any number of things. From profile to finish. So you might ask is that mil. spec. 16 inch barrel I picked up at the gun show for a really really good price marked .556 really going to hold up to that "NATO "ammo from commie country ?

[HWB13]

My recommendation is not to use 7.62x51 machine gun ammo in a rifle chambered for 308.  Besides possible pressure problems, I found it to be inaccurate.

I don't have a 308 Handi yet, but i do have a Mohawk 600 in 308.  Years ago, don't you hate when stories start that way, I was the RSO on the M60 range one day and was sitting on a case, 1 case 2 ammo cans, watching over the range.  When it was all done i had forgot about the case I was sitting on filled out paperwork all rounds expended.  Went to get up and oh sh*t another case.  I will swear on a stack of bibles it wasn't on purpose.  Well instead of changing the paperwork just took them home.  fired them for years with no problem and had no issues with accuracy.  Still have all but a few of the tracers belted together in the gunroom.

[SHOOTALL]

The short answer is:

You can use 223 ammo in a rifle chambered for 223, and 5.56.
You should not use 5.56 ammo in a rifle chambered for 223.
You will also void any warranty you have on H&R guns if you use military (5.56) ammo.

You can use 7.62x51 ammo in a rifle chambered for 308.
You should not use 308 ammo in a rifle chambered for 7.62x51.

My recommendation is not to use 7.62x51 machine gun ammo in a rifle chambered for 308.  Besides possible pressure problems, I found it to be inaccurate.

Why ? I can see not using it if you have a fluted chamber and the brass is soft enough to cause sticking . Or if it is sealed with asphalt which will condensate after firing causing an oily mess. But I have shot it with good result back in the day when you could buy good clean ammo.

[OldSchoolRanger]

My recommendation is not to use 7.62x51 machine gun ammo in a rifle chambered for 308.  Besides possible pressure problems, I found it to be inaccurate.

I don't have a 308 Handi yet, but i do have a Mohawk 600 in 308.  Years ago, don't you hate when stories start that way, I was the RSO on the M60 range one day and was sitting on a case, 1 case 2 ammo cans, watching over the range.  When it was all done i had forgot about the case I was sitting on filled out paperwork all rounds expended.  Went to get up and oh sh*t another case.  I will swear on a stack of bibles it wasn't on purpose.  Well instead of changing the paperwork just took them home.  fired them for years with no problem and had no issues with accuracy.  Still have all but a few of the tracers belted together in the gunroom.

If I remember correctly, this is a prime example of Marine requisitioning.    Not to worry, I'm not calling you a liar, it just reminds me of our "typical requisitioning" of supplies from non-combat units.  We always felt we had a "real" need for some of the stuff that REMF units had, and that we didn't have.  I think it was also called scrounging. 

[OldSchoolRanger]

The short answer is:

You can use 223 ammo in a rifle chambered for 223, and 5.56.
You should not use 5.56 ammo in a rifle chambered for 223.
You will also void any warranty you have on H&R guns if you use military (5.56) ammo.

You can use 7.62x51 ammo in a rifle chambered for 308.
You should not use 308 ammo in a rifle chambered for 7.62x51.

My recommendation is not to use 7.62x51 machine gun ammo in a rifle chambered for 308.  Besides possible pressure problems, I found it to be inaccurate.

Why ? I can see not using it if you have a fluted chamber and the brass is soft enough to cause sticking . Or if it is sealed with asphalt which will condensate after firing causing an oily mess. But I have shot it with good result back in the day when you could buy good clean ammo.

SHOOTALL - Is this question directed at using 308 in a 7.62, or at the use of 7.62 machine gun ammo in a rifle chambered for 308.

[HWB13]

Old School,  I am not a stranger to creative requisitions.  Had to do more than my share to get the job done, that day was not one of them.  Did alot of R&D and creativity on a Marine Corps budget, no thanks to the sister service, was the name of the game.  Still have a tendency to build before I buy.

[SHOOTALL]

The short answer is:

You can use 223 ammo in a rifle chambered for 223, and 5.56.
You should not use 5.56 ammo in a rifle chambered for 223.
You will also void any warranty you have on H&R guns if you use military (5.56) ammo.

You can use 7.62x51 ammo in a rifle chambered for 308.
You should not use 308 ammo in a rifle chambered for 7.62x51.

My recommendation is not to use 7.62x51 machine gun ammo in a rifle chambered for 308.  Besides possible pressure problems, I found it to be inaccurate.

Why ? I can see not using it if you have a fluted chamber and the brass is soft enough to cause sticking . Or if it is sealed with asphalt which will condensate after firing causing an oily mess. But I have shot it with good result back in the day when you could buy good clean ammo.

SHOOTALL - Is this question directed at using 308 in a 7.62, or at the use of 7.62 machine gun ammo in a rifle chambered for 308.

I believe it was about MG ammo in a rifle . I have shot such with out any problem , it was US manf. At one time is was aval. cheap at gun shows here 840 rounds to a case If I remember correctly ( wooden crate with 4 ammo boxes in it) cost 40 to 50 bucks back then. There was also foreign manf. as noted above.  I don't know how they would work in a break open gun though.