Ruger SR-762 Review: Part 5 - Internal Features

Ruger SR-762 Rifle Review
Part 5 - Internal Features
February 16, 2013

In this part of my Ruger SR-762 review, I'm going to give you a look at some of the internal features of this rifle. For reference, you can also take a look at the internal features of Ruger's SR-556C and SR-556VT rifles that I have reviewed in the past. Ruger has taken a common approach for incorporating their piston system into all these rifles and some components, such as the gas piston, are actually the same for all rifles. The Instruction Manual Insert for this rifle shows the SR-762 has 37 unique components. Considering the SR-762 chambering in 7.62x51 compared to that of the SR-556 chambering in 5.56 NATO, there are no real surprises on this list, although I was a little surprised to see that a buffer and buffer spring were not identified to be unique for this rifle.

Figure 1
Ruger SR-762 Review

Since the piston system is a significant feature for this rifle, I will start this part of my review with this feature first. The two-stage gas regulator works by gasses passing through a hole in the regulator and then applying pressure against the smaller diameter of the piston that is inside the regulator.

Figure 2

Once the piston is pushed out of the regulator, gas pressure can then act on the larger diameter of the piston. Ruger claims "the two-stage piston provides a smooth power delivery stroke to the bolt carrier". From an engineering perspective, I can believe this, but since it is difficult to test this claim, I will have to take their word on it.

Figure 3

By looking down at the lower surface of the cavity in the gas block, you see the large area where the regulator pin protrudes up to secure the regulator. Just behind that you see the gas port that allows gas to pass from the barrel to the regulator. The last two holes that are offset on the right side of the gas block (left in the photo) allow the gas to escape from the gas block once the piston passes to that point during its cycle.

Figure 4

The gas regulator is marked with the "7.62" marking and this regulator is unique to the SR-762 rifle. The portions of the regulator that see hot gasses are chrome plated to ease cleaning efforts.

Figure 5

The regulator has three different diameter gas ports that correspond with the 1, 2 & 3 markings on the regulator. The gas port diameters increase with number so that the "3" marking relates to the largest diameter port. So far, this rifle has only been fired using the "2" gas regulator setting and you can see evidence of this by looking at the burnt area only around the middle port in the photos below.

Figure 6

Figure 7

These next photos give you a look at the chrome plated gas piston.

Figure 8

Figure 9 Figure 10 Figure 11

The chrome plated bolt and bolt carrier look to be well crafted components and the combination of chrome plating along with the piston system should make cleaning these components in the future extremely quick and simple.

Figure 12

The bolt carrier is manufactured from ANSI 8620 Nickel-Chrome-Molly Alloy Steel and case hardened. The bolt carrier is a one piece unit and all the critical wear components of this part are chrome plated. I was very impressed with the "smooth as silk" feel of moving the bolt within the carrier body. Some of the less critical areas of the bolt have tooling marks from the machining process, but all the areas that would be considered as contact points while the action cycles appeared to be polished to a smooth finish.

Figure 12

Figure 13

One of the significant features of this piston AR is that there is no need for a gas key. The piston pushes on a transfer rod that pushes directly on the lug that is integral to the bolt carrier. This eliminates the potential for the gas key working loose.

Figure 14

One detail that I was surprised to see was the recess in the bolt for the bolt carrier cotter pin. Typically this recess is a circular/conical recess which allows you the ability to pull the pin using some type of needle nose pliers. On the SR-762, the shape has an oval slot for the head of the pin and a small cutout above the pin to allow you to pry the pin out using a small screwdriver or punch.

Figure 15

It is hard to notice in these photos, but the rear of the bolt carrier is actually a larger diameter to reduce carrier tilt.

Figure 16

The rear end of the carrier also has a generous radius to ensure that the carrier transitions into the buffer tube without issue.

Figure 17 Figure 18

The next few photos are to give you a better look at the bolt assembly. The bolt is also manufactured from ANSI 8620 Steel, case hardened, and magnetic particle tested. Ruger also proof pressure tests each rifle with one round that has a powder charge to produce a chamber pressure 40% higher than the maximum operating pressure for the caliber.

Figure 19

In general, the bolt appears to be a scaled up version of a 5.56 bolt. There is an 8 lug pattern if you include the extractor lug and the extractor and ejector seem similar to the 5.56 configuration.

Figure 20

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Ruger SR-762 Review

Figure 24

Figure 25

Since I was showing detailed photos of other components in the bolt carrier group, these next two photos give you a close look at the cam pin and firing pin.

Figure 26 Figure 27 Figure 28

Figure 29

Other than a difference in length needed for the increased length of the 7.62x51 round, I didn't see any real difference in the overall design of the charging handle.

Figure 30

Figure 31

When looking inside the upper receiver you can see the end of the transfer rod that makes contact with the bolt carrier lug when firing the rifle.

Figure 32

The barrel extension and upper receiver include the M4 style feed ramps.

Figure 33

Figure 34

These next two photos give you a look inside the upper receiver.

Figure 36

Figure 37

Since AR-10 style rifles have no true industry "Mil-Spec" configuration, manufacturer's are free to tweak their receiver profiles to meet their design goals without having to worry about commonality of parts with other manufacturers. At this time I have no idea if the Ruger SR-762 upper or lower receivers are compatible with any others on the market. Fortunately, Ruger realized that the ability to install aftermarket triggers and safeties is something that would be desired by the consumer and the trigger interfaces on this rifle are compatible with other AR-15 style aftermarket components. These next few photos give you a look at the internal components in the lower receiver.

Figure 38

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Figure 41

One concern that seems to come up on a regular basis is carrier tile wear on the bolt carrier and buffer tube. The SR-762 has a shelf to support the rear of the bolt carrier when the carrier is not inside the buffer tub. This shelf also helps to act as a guide so that the bolt carrier will transition into the tube without issue.

Figure 42

The photo below helps me to document the current new state of my buffer tube to help me evaluate if wear will be an issue in the future.

Figure 43

The rifle comes with a 3 ounce buffer which appears to be the same as that for Ruger's SR-556C rifle.

Figure 44

The buffer spring measures about 13.75" in length.

Figure 45

Thoughts

After completing this part of the review, my thoughts are no different on the SR-762 than that when I reviewed the SR-556C and SR-556VT. Except for the differences due to this rifle having a piston system instead of gas impingement system, the SR-762 appears to be your same basic AR styled rifle but in a larger caliber.

For more detailed photos and commentary, make sure you check out the other parts of this review and feel free to leave comments on my Reader's Comments page. The following links are provided to help you see other parts of this review.

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