I need help with some barrel markings

[colocowboy01]

I have come across an AR barrel from a trade with the markings 5.56 1/7 HPMP. I understand the 5.56 (caliber) and the 1/7 (twist ratio) but can anyone help me with the HPMP? Who is the manufacture of this barrel?

[ldmaster]

The additional stampings are sometimes a barrel designation for a custom run. They use it to mark the special run barrels. I have one from a run for the dutch miliary that has three letters that were a contract designation that they had to put on the barrels per contract. I've only seen that stamp on one other barrel, and it was from Bravo Company, they would know what it means if it's their barrel.

[colocowboy01]

Thanks Idmaster. I will check with BCM to see if it is one of theirs.

[mutt]

High Pressure and Magnetic Particle tested? BCM barrels tend to have that marking.

[gcrookston]

High Pressure and Magnetic Particle tested? BCM barrels tend to have that marking.

--- correct. You'll find 'HPMP' on higher grade barrels, such as mfg'd by Sabre (now defunct), Colt and even Stag Arms.

[ray1970]

Are you sure it is "HP" and not "HF"? The HF could be hammer forged. The MP, like others have stated, is Mag Particle.

[gcrookston]

HPT / MP Inspected Barrels
Military specifications require that barrels undergo a HPT (High-Pressure Test) load as a part of quality assurance procedures. Commonly referred to as a proof load, the M197 HPT is rated for 70,000 psi. BCM barrels are proof loaded and then MPI (Magnetic Particle Inspected) to detect any possible flaws in the barrels surface. The barrels are MP inspected with both circular and longitudinal magnetic fields per ASTME1444-01 (current Mil-Spec) to assure a high quality finished product. All BCM barrels are marked HP MP as our proof load marking.

In addition, Bravo Company marks their barrels HF -- hammer forged



see:http://www.m4carbine.net/showthread.php?t=36858

[colocowboy01]

My barrel looks very similar to the one in the picture except for the HF, for hammer forged. Not having the HF marking, does that preclude my barrel from being a BMC?

[mutt]

My barrel looks very similar to the one in the picture except for the HF, for hammer forged. Not having the HF marking, does that preclude my barrel from being a BMC?

No, not all barrels from BCM are hammer forged. You got me curious about my BCM uppers so I went and checked the markings. My Bravo that isn't hammer forged is marked HP MP. The one that is hammer forged is marked BFH HP MP.

[leatherneck448]

as others have said, the HPMP stands for high pressure/magnetic particle tested.
not all bravo co. uppers have the BFH marking as they sell both hammer forged and non-hammer forged barrels,
so not having that stamping does not necessarily mean that your barrel isnt a bravo company.

My bravo company barrel has these markings right in front of the FSB as others have shown in the pics.

if you have a BCM bolt, these markings (HP/MP only) will be laser engraved into the side if it as well

hope this helps,
Kenny