XY Embossing

XY Embossing - Observation and Theory

What is XY Embossing?

It's the X and Y shaped embossing (stamping) seen on the left (where a side rail would go) side of the receiver, centered where the trigger axis pins would enter through the receiver. This is the typical XY embossing seen on most AKs in the US:

A single "X" and a single "Y" that is rounded at the ends. How did we get here and why is it even a thing?

Why is it there?

When the AK-47 was continuing development it was decided that Soviet stamping technology had reached a level where they could resume producing AKs with a stamped receiver once *again* (prior to 1959). [They were using milled receiver variants after the first AK-47 had consistency issues where they made the switch to the transitory Type II model, and then settled on the Type III model until technology improved]. When the AKM was designed, the Soviets elected to use an approximately 1mm thickness stamped receiver; this lightened and cheapened receiver (among other design changes) called for some parts to be changed to accommodate the redesign. The Soviets, seeking to minimize as much part change as possible in order to save costs and to use up existing parts, decided to reuse the existing trigger axis pins, springs and hammers and, possibly, triggers.

The Milled receivers these trigger systems were designed to fit in, however, had smaller internal dimensions because the receivers were thicker (~1.5mm compared to the new ~1mm) so in order for the trigger system to index properly, and to reduce pin wiggle, they decided to add a ~0.5mm deep embossing to the left side of the receiver in the 3 places that the pins would enter the receiver. And that's why you don't see this XY embossing on Type I, II and III AK-47s, but you see it on the AKM and other ~1mm thick receivers.

Why don't I see this XY embossing on other stamped AKs like the RPK?

The RPK has a reinforced receiver of approx 1.5mm thickness, so it does not need XY embossing. This also goes for the Chinese AKs, the PSL, Yugoslavian AKs (with some thin receiver exceptions and another opposite exception in the PP-19 Bizon as it has XY embossing because even though it's a thicker receiver it's not as thick as an AK-47 milled receiver).

No XY Embossing Chinese Mak90:

Mak90 noXY.jpg

Why do some AKs only have 1 "X" and 1 "Y"?

These are commercial AK receivers brought/made in the US because it is illegal to have a 3rd axis pin for an out of battery safety (auto-sear), so in order to be even cheaper, the manufacturers saw that they could take 1 more action out of the process (or perhaps they just didn't want their rifles being rejected by the ATF by any means). If there will never be a 3rd axis pin, why emboss it? (It could also be something they did in case any more restrictions would have taken place via an "assault weapons ban" of sorts) Note: some receivers still have 3 places with embossing as some manufacturers didn't want to change their production facilities to accommodate the small savings it would bring (or they thought the ATF wouldn't care).

Why do AK-74s have different XY embossing?

This one is interesting. And all I have to go on is theory.

In 1973 (maybe '74) a change was made to the receiver production at Izhmash; they were starting to re-tool in order to produce the new AK-74. During this retooling the XY embossing also changed so that the auto-sear axis pin hole went from having embossing that looked like an upper-case English "Y" to more like a lower-case English "y". I believe this change was implemented for either manufacturing simplification or for inspection reasons. The inspection reason being that the night-vision optic mount (side rail) underwent a change to be lighter, more streamlined, and to fit the new AK-74 rear trunnion rivet pattern. The upper left portion of the usual AKM "Y" embossing on the auto-sear pin would have been overlapped by the side rail, but in it's shortened "y" configuration the whole embossing is visible (pic in Tula section at the bottom page).

The Izhmash factory did not stop production of the AKM in 1973. They continued to produce them alongside the new AK-74 until a later date, but both rifles used the same XY embossing as each other, therefore AKMs produced by the Soviets after 1973 have the SAME XY embossing pattern as the AK-74! Other rifles that use this same pattern of embossing are: PM.Md-86/AIMS manufactured by Sadu in Romania, 5.45 rifles made by K3 in East Germany, and AK-74s made by Arsenal in Bulgaria. The thing all of these have in common is that they received the AK-74 and 5.45 data packages from the Soviets, who they still had good relations with at the time.

MPiK74 Example (near and far):

Sadu 1992(?) MD.63 (top) vs 1992 Cugir MD.63 (bottom):

No other country received a 5.45 data package (except Poland, who designed the Tantal which is very different) and therefore no other country saw an update to its XY embossing. They all continued to use AKM XY embossing (if they did at all).

Notable Mention

Tula

Tula is the only factory I've seen AKs that had different XY embossing from the rest of the world. The Tula manufactured AKM was different than the Izhmash AKM. The XY embossing from Izhmash (and the rest of the world) have rounded ends on their embossing, whereas the ends are squared off for Tula.

Comparison (Tula on top):

This embossing style also changed in, not 1973, but *1971*, to this unique pattern (Tula on top):

The Tula AKMs after 1971, and the few Tula AK-74s are the only rifles that have this style of embossing. I have no idea why they did this. More perplexing, still, is that the Tula AKS-74U uses a style of embossing more akin to Izhmash, even though it was produced at Tula. The Izhmash 1973 embossing style is still the style used on Russian AKs today, such as the AK-12 and AK-15.