AIA in 7.62x39 issues.

[32ndgeorgia]

I have this rifle and it does not shoot military type ammo ie: Wolf and milsurp well. In fact, I don't think I could hit a barn shooting from the inside.

It will shoot 154 grain softpoints reasonably accurately, however.

I have to wonder if there is a chamber problem. Also, I wonder if the barrel is
.310 or .308. The 123 gr. millitary ammo will not shoot accurately at all.

Do any of you Australians know anything about these rifles?

Thanks in advance for any information.

Information

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[Bruce_in_Oz]

You have one of my feral children there.

The barrels are pretty much to Russian AK bore spec: 0.311 groove, 1:10(ish) RH twist, hard chromed bore and chamber.

These barrels were made to drawings of original Russian spec. I was a little perplexed about the form of the rifling as it has sharpish edges. Sharp corners and hard chrome are not a good combination. If you examine a chrome-lined L1A1 or M-14 barrel, you will note that the flanks of the lands are angled and the corners at the root and crest of the lands are radiused. The 1:10" twist is way too fast for the short, 125 (ish) grain bullets. Its use is in keeping with "economy" measures; Nagants and Tokarev pistols used the same rifling form and twist as the AK. It all started with the long, round-nosed bullets used in the Nagant in the early 1890s. Not unlike the 1:10 twist in ALL Lee Enfields, but that is another story.

Two problems can occur with the chrome:

1. If the application is not correctly controlled, small nodules form on the run-out of the rifling at the muzzle. These can cause irregular turbulence and bullet deflection at the worst possible point in the bullets flight; launch.

2. If the steel substrate is not immaculate before plating, coverage will be variable. Defects will allow the propellant gases to penetrate the rather peculiar crystal structure of the plating and it is all downhill from there.

Finally, as the 1:10" twist is WAY to fast for the little short bullets, they tend to precess quite a bit just after leaving the muzzle. This precession will be exacerbated by any defects in the bullet construction. This is very noticeable at short (out to 75yds) range, as they settle down a bit after that. Most of the bullets in "MilSurp" 7.62 x 39 ammo out there have a structure as follows:

Inner hard-steel core, covered with a THIN sheath of lead.
Around this is wrapped the outer jacket, usually made from mild steel.
This steel jacket is plated with a THIN film of Copper alloy.

Jugoslav ball ammo tends to be constructed on more "Western" line; having a soft lead core and a "gilding metal" (mostly Copper) jacket. The Russian/Chinese "steel/lead/steel" construction makes for more possibility of manufacturing error and potentially poorer dynamic stability when spun at speed.

Basically, firing a less-than-perfect bullet of compound construction through a barrel with the tiniest imperfections at the muzzle will give you less than ideal results.

Have you tried Jugoslav ball or any of the "commercial" brass-cased, "Western" bulleted ammo like Hornady? The other problem encountered with any of the steel-cased stuff, excluding the later Russian "grey" ammo, was fired cases giving "hard extraction". This is caused by a build-up of lacquer from the fired cases. When the round is fired, the cartridge case expands and gets quite hot. The lacquer on the neck melts a bit and some is transferred to the chamber. In a gas-operated toy, extraction takes place as chamber pressure is dropping but whilst the case and chamber are quite hot. Thus, the case is free to go. To see how little heat is transferred to the chamber pick up a case that has been freshly ejected from an AK or SKS. Most folk only do it once.

In a bolt-action, you cannot cycle the bolt that fast. Thus, a considerable amount of heat is drawn away by the barrel acting as a fancy heat-sink. The melted lacquer re-solidifies and impedes extraction. Note that even steel-cased ammo that has a Copper outer "wash", is given a final thin coat of lacquer to prevent tarnishing of the Copper and subsequent corrosion of the steel case. If you can only get Mil-Surp ammo, try to use the "Copper-washed" stuff as it tends to have a lighter lacquer than the "green" or "brown" stuff. The Russian ammo with the grey "polymer" case coating seems to be the pick of the steel-cased ammo for the AIA carbines.

Finally, I have not had any affiliation or association with AIA for quite some years, so I can't really help much more except with background stuff.

[Thunderbox]

I think they're just ammo sensitive: my AIA M10 shoots relatively badly with Wolf (UK bought) - about 5-6 moa at 100 yds - but shoots very well with East German surplus - about 2 moa or better. One type of surplus (my supply comes in mixed batches of at least four different types) is exceptionally good - better even than some Lapua commercial that I tried.

The rifle is very good at 200-300yds, so that is interesting to hear Bruce's explanation.

[enfield303t]

Well I have had the sticking case issue and seems to be solved using Russian(grey) surplus and my gun is really quite accurate. My Czech ammo is a real problem in my AIA so stopped using it.

I guess I feel fortunate that mine shoots the surplus very well and to be honest seeing as the ammo is so inexpensive that is why I bought the gun.

It would be interesting if we could compare the internals of our guns to see if there is a glaring reason yours has the accuracy problem.

[32ndgeorgia]

Thank you so much for the information. It sounds like a re-barrel is in order. Maybe one in 1:12 would stabalize the 123 gr. military ammo.

Thank you ever so much.

---------- Post added at 09:05 AM ---------- Previous post was at 09:04 AM ----------

Having another thought. How hard would it be to convert this rifle to 7.62x51 NATO?

[Bruce_in_Oz]

The issue of stabilisation is a bit tricky:

For a given bullet and air density, long bullets need to be spun much faster than short ones. If you are getting proportionally better groups at 200 yds than at 75yds, that is just physics at play. Ask a few of the older chaps who shoot Lee Enfields out to 1000 yds about bullets "going to sleep". There should be no need to re-barrel unless there is a lot of chrome missing from inside your barrel or it has been damaged in some way.

The extraction difficulties only became apparent when end-users started complaining about it. ALL of the factory testing was done with the copper-washed ammo, which produced very little drama. Endurance testing meant that the barrels were so hot that stickyness was not a problem. You live and learn.

The change to 7.62 NATO involved several changes to the receiver proper, a different bolt head and a very different magazine adaptor.

The original idea was to produce a "universal" receiver that would accept a suite of adapters that actually retained the magazine and also featured appropriate guiding surfaces for the cartridge family in question.

As the barrel is retained by a collar system exactly like the Savage 110 series: (the thread is Imperial, UN form but NOT a standard "off the shelf" job), getting a good gun-plumber to replace one is not too hard, just expensive. BTW, the thread that retains the frontsight/flash-hider assembly is a "metric special".

Opening out the face of the bolt head is quite simple, just that the extractor will meed replacing or "adjusting".

Playing with the magzine adapter will keep someone amused for many long hours. The mag used in the "B" series M-10s was essentially a facsimile of the 10 rd M-14 mag.

If you are really desperate to rebarrel, stick with 7.62 x 39 and use a .308 spec barrel with 1:12 twist; stainless is optional.

The cheapest option is to find ammo that your rifle "likes" and grab a swag of it.

Or, if you are feeling adventurous, go for a version of the old ".220 Russian" which is a 7.62 x 39 simply necked down to .22. At least you don't need to change the mag or adapter. Then there is 6mm PPC, which is a .220 Russian blown out with almost parallel sides and driving a 6mm bullet. It is one of the most efficient and accurate small cartridges on the planet. Caveat on that one is that it reaaly needs its own special mag.: a bit like a Galil mag with a lighter spring and slightly wider lip gap. The cool thing is that you only need to remove a small amount of metal from the adapter to make them fit and function.