Quick question for the specialists. I just recently came into ownership of the above rifle. While researching ammo I came across some bulk 7.62 x 51 173 gr. military match ammo for sale in bulk. The gentleman asked me to verify this round will be suitable for my firearm. His concern, if I understood him right, was total length of the casing with round because of the heavier grain bullet. I assume if my firearm is chambered in 7.62 then there should be no concerns regardless of grain? I do plan on picking up a box to try out first. Any opinions? Thanks for your time.

His question likely pertained to whether or not the ammo will fit in the mag.

Sorry for the lack of clarity in my post. I was a bit confused from my first conversation with the seller of the ammo. I compared a 173 gr. round to what I had in my stock which is ball m80. The match round is slightly longer, maybe no more than a 1/16 of an inch. I think there will be no issue with using the match round.

Went to the range. First 20 rounds 173 gr. match ammo had a handful of failure to feed. Using Pmag25 Gen3 magazine. Those rounds seat inside the mag with minimal clearance front to back. Not sure these rounds are friendly to Pmag 25. Had no failures to eject or failures to fire.

Get the mag for that ammo and it'll be fine.
Magpul makes Pmags for that too.
https://www.magpul.com/product...8-lrsr-gen-m3-window

Thanks for the response and the link powermad. That is exactly what I am using for mags. I am absolutely new to the world of AR's so no doubt I need to become familiar with the idiosyncrasies all around. Is it not unusual to experience a break in period on these pmags in which they perform with fail to feed?

There are two different 7.62x51 PMAGS.

PMAG 25 M118 LR/SR for 7.62x51 M118LR or other .308 Winchester match ammunition with a max OAL of 2.830"

PMAG 25 LR/SR for regular ol M80 type ammo.

The ammo you have needs the M118 LR/SR marked one.

They don't need breaking in.
Just don't drop one when loaded, apparently they don't like that and split the feed lip at the rear.
Magpul was kind enough to exchange two of them for me when I asked about buying new bodies.

Oh yes now I see! The mag that came with my rifle has "LR/SR". The two pmag 25's I bought after have stamped "LR/SR W". Thanks for your help.

Pmag 10 Mfg part# MAG290
Pmag 25 Mfg part# MAG577

These are for the M118 round no longer than 2.830".