I was happily receiving advice about the AK, when someone mentioned there is an issue with Arsenal milled receivers. I know nothing of this, and wonder if this person just got a bad one, as this can happen with anything, or if this indeed is an issue that might rear its head with my rifle (SA-M7-01 that I just bought, but have not yet received).
If you own any milled Arsenals, I hope they run fine and last you a lifetime, since Arsenal of Bulgaria
specifies the lifespan of the rifle at 15,000 rounds.
I understand and know what normal wear of a firearm is or looks like, and I can spot abnormal wear too.
Now, to this carrier bull shit.
The thickness of top rails on milled Arsenals is not same. They vary as much as .012 " which is appx 1/64".
The thinner top rails, the more carrier slop, and bigger carrier hole where the bolt stem rides compounds the slop.
German carriers and current military issue full auto Bulgarian carriers, which at one time were available from K-Var
are machined more precisely than the semi-auto ones you find on Arsenal rifles.
German carrier and full auto Bulgarian carrier (which is no longer available anywhere) reduce bolt slop and thus reduce the wear of trunnion and ejector
in the areas marked A and B.
The pic is of milled Arsenal … top rail thickness .058". Rifle fired less than 500 rounds.
In case of this Arsenal, I had to modify the clearances on the bolt itself, and run it in a German carrier to prevent further unnecessary receiver erosion.
I don’t have any pics of the bolt after mod, but I assure you, that critical working areas of the bolt have not been altered.
The front part of the bolt has been modified to resemble German bolt and the clearance of one surface has been increased.
This is more complex and I do not wish to bore anyone.
Recently I bought some brand new Polish AK carriers from Apex. I cycled one of them in this rifle and it runs identically like the German one.
Bulgarian semi-auto carriers are fine for stamped receivers or paper weight.
On the final note, if the thickness of your top rails is in the neighbourhood of .065 - .070 then you have nothing to worry about.
I was also interested in purchasing an SA-M7-01. They seem to be at the right price point.
I think posting photos of the rails with a ruler next to them online (to gauge tolerances) would probably be your best bet. If it hasnt shipped yet, I would have someone personally look at your rifle and measure the tolerances before shipment. This may seem neurotic, but as far as Im concerned over 1600 dollars is an investment, and you expect a quality product which will last a lifetime.
I contacted KVAR and asked a few questions that seemed to be pretty simple (at least to me) but I never received a response regarding the SA-M7-01. If anyone could answer these questions that would be appreciated
1.) Are the internals Bulgarian or Russian Internals?
2.) Is the milled receiver heat treated?
3.) What makes this different from the SA-M7-R?
You’ll first need to clarify which receiver he’s talking about. The current milled AK’s that Arsenal is offering have US made receivers. Older Arsenal rifes came with Bulgarian made receivers. As far as I know, the Bulgarians and the Chinese are the only ones making milled AK receivers. Actually, I’m not even sure if the Chinese still do. I’d find it hard to believe that the Bulgarians, who have made a ton of milled receiver AK’s, wouldn’t be getting things right. As for the US made receivers that Arsenal is using in these current rifles, who knows? I’m sure that Arsenal, Nevada doesn’t make them because their gunsmithing skills leave a lot to be desired. Whoever is making them may or may not be producing a quality product. I honestly don’t know.
Here’s a point to consider. The top to bottom rail thickness on a milled receiver AK and a stamped receiver AK are suppose to be approximately the same. In order to make the 1.0mm stamped receiver rails thicker, they have what’s called a step down. The rails are just bent down slightly inside the receiver to create extra thickness top to bottom. Thicker 1.5mm stamped receivers don’t require this step down to get their rail thickness approximately the same as those of milled receivers.
I’m not trying to rain on anyone’s purchase, but in my opinion, the price is way high for what you get. You’d be better off buying an SLR-95 or SLR-96 and converting it (easy) yourself.
There is nothing wrong with quality stamped receivers that they convert. It’s like folks buy these milled lowers and tout them like a talisman or something.
On the way into battery, when the left lug of the bolt enters the channel in the trunnion, surface A is supposed to deflect it downward.
This angled lead is there for a reason, not for decoration.
In some cases, due to too much carrier-bolt slop, the front corner of the bolt (circled red) will deflect the bolt into the channel and cause
the trunnion wear as shown in previous pic.
To check this:
Tie the trigger to pistol grip; pull hammer back so that disconnector will hold it. This will allow for a longer stroke of the
carrier without the interference of the hammer.
With recoil spring removed turn the rifle up-side down.
As you slowly ride the carrier forward into battery, observe from the side of receiver which part of the bolt hits the trunnion.
You may also view from the magwell how the bolt rides over the ejector.
From here on, you’ll figure out the rest.
Below:
Arsenal bolts. Left, SA-M7-R; middle SA-M7-A1; right, Arsenal Classic.
You can see that bolts on the left do not have the leads (red circle) machined in like the one on the right.
What appears like a lead of the middle bolt is actually peening formed by head-on collision with the ejector.
I’m not sure its a screw up. Mine with fifty rounds already looks nearly the same. I am wondering if its not similar to the “ramp” worn by an m4 cam pin in an upper behind the cutout.
