Experimenting with HXP

[JAS]

Somewhere, I read that breaking the seal around the bullet on the CMP's Greek HXP would improve accuracy. I decided to test this theory. All rounds came out of the same spam can of HXP-69 which has proven to be very accurate ammo. All rounds were first weighed to eliminate any highs and lows and then spun to eliminate any round more than .006 inches out of round at the bullet. 54 rounds produced 40 matched rounds and 14 rejects. The rejects were set aside and not used in the test. I then took twenty of the matched rounds and ran them up into a Bonanza bench rest bullet seating die set to push the bullets another .010 inches into the case. On each and every round you could hear the sealant make a distinct cracking sound as the sealant was broken. I then retested these rounds for runout and if anything, the Bonanza die made them even straighter.

The results were not what I expected. The rounds with the bullet sealant broken were terrible. The undisturbed rounds still produced the same accuracy that this lot of HXP-69 has been good for in the past. Now, this test is with one lot of HXP in one M1 Garand. I am not saying that anything should be etched in stone here. But I am suggesting that before you set up your bullet seating die and break the sealant on 500 rounds of HXP, you might want to do a little small lot testing.

All rounds were weighed and spun for consistancy:



Accuracy with the undisturbed rounds was what I have come to expect from this lot of HXP. Half of these rounds were fired single fire using a sled and half were fired semiautomatically rapid fire:



These are the broken sealant rounds fired the same way, half single fire and half rapid:



Further testing at 200 yards slow fire prone on a NRA SR target showed that while the undisturbed rounds would hold the ten ring when I did my part, the broken sealant rounds would not stay in the black no matter how careful I was.

Information

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[BruceV]

Based on what I've read and my own small experience, your results are not what I would have expected. When it comes to the good things of life like accurate rifles and loads, the words of little Alice come to mind, "...Curiouser and curiouser!" Thank you for the post and especially the pictures. Sincerely. BruceV.

[phil evans]

as a retired wildlifer i like:
replication:
i.e. the ability to document what has occurred again and again.
side by sides:
ammo was modified and performed this way;
that's with repeatable results.
consistancy under adverse conditions is paramount for battle ammunition
additionally, knowledge based upon expected results is enightening.
i've got 2 cans of greek coming and your expected results will be a benchmark.
thanks for your work.

[0311Shooter]

Got in a genuine pizzing contest on the old forum about this. Here's my take on the LC M2 Ball and also the HXP. If you want reloading type accuracy with these, you won't get it. Unless...

Here is what I did with my LC ammo that I bought from my Gun Club. Took three boxs and I pulled all the ammo, weighed all the powder of each round, then weighed all the bullet tips. Found the powder varied by about half a grain. But the bullet tips, THERE was the culprit. They varied by a full grain on some, from half a grain below 150 gr, to over half a grain above 150 gr.

Then I proceeded to take the back of those above 150 gr, drill a small hole in the center, weighed, drilled, weighed, until they were exactly 150 gr. Those under were tossed aside to make practice rounds. Then took the average of all the powder loads, reloaded each round to that average. Out of three boxes of 60 rounds, got 50 - 55 PERFECT rounds.

The jist is to be CONSISTENT, because once you get on the range and sight to your spotter rounds, the rest of them will be the same.

IF your rifle is well tuned, and IF you are good, then you will shoot a perfect round.

[Griff Murphey]

In the 60's Marines were big advocates of breaking bullet seals on 7.62 match. I remember them using Lyman tong tools to do this. Also checking with bullet spinners was a big deal.

[High Plaines Doug r]

The 1st batch of HXP I bought from CMP was headstamped 1972 and shot OK; very much like Lake City available at the time: held the 10 ring off sandbags. I broke the bullet seal on them in a Lee press and thought I got better results, so I was happy.
I have 2 orders of HXP on hand now: 1965 and 1967 and they both almost hold the "X" ring at 200yds off sandbags so I don't mess with them.
It pays to plan your experiment and document the results. The '60's era HXP seems to be very good ball ammo.
Of course, YMMV.

Doug

[Mizzouboy]

I bought 4 cans of HXP from the CMP about a year ago. Lots vary from 69-72. The stuff shoots great in my minty H&R Garand. I also have a very nice 1903A4. Trouble is, I can't hold 6" at 100 yd with the HXP and 03A4. The 03 shoots great with 168gr match handloads in HXP brass. Did the US issue any special ammo for snipers? I don't recall any, at least during WW2? It sure doesn't like HXP loads...