Lake City M2 Ammo problem/question

Posting on both ammo and M1 garand threads.

I have a quantity of LC 66 lot 422201 and LC 69 'Talon' (repackaged) M2 ammo, which was sold in qty by CMP in the past.
I noticed it didn't shoot as well as expected, out of an excellent barrel. I decided to get to the bottom of the problem.

I chronographed both. The 66 clocked at about 2520 and the 69 at 2420. I tried a second chronograph and got nearly identical results. I then tried some HXP 77 and it clocked at 2710 (as expected).

Bad powder or primer? Let's find out. I took a couple fired cases, put in a CCI34 primer, and dumped the powder contents of several rounds into those CCI-34 primed (resized) cases, and reseated the bullets. They clocked at about the same speed as before, indicating the original primers were still good and the powder must be going bad (it looked and smelled fine).

Has anyone else had this experience? Is there a solution? Can I pull down all the powder and re-work an increased powder load to bring the velocity back up to spec? I'm thinking of pulling down all the powder, blending it thouroughly, and working up a new load for that lot of powder. I know surplus pulldown was on the market for decades and each lot had to be worked up.

Any info/advice would be helpful.

I shot some LC Talon repacked ammo and it pretty much shot to M2 ball expectations, so I didn't have your problem. Most of the Talon re packs were old machine gun ammo (did your ammo have the discoloration from the belt links??) which may have had something to do with your problem or it may just have been a bad batch. Talon made its living originally converting tracer and incendiary ammo to M2 ball. I don't know if the CMP got any of that stuff but if they did perhaps the problem came in the Talon remanufacturing process.