Receiver Blue Printing

The Remington 700 Receiver is probably the most used receiver in today’s custom builds. With slight modifications to key locations on the receiver they can become part of a very accurate rifle. The following is my truing / blueprinting process to show what I actually do. The first picture shows how most receivers look after the barrel has been removed. The gunk is some sort of thread lock Remington uses.

The next pictures show the receiver with a truing collar I made, the bolt raceway bushings and a hardened, ground .500” indicating bar. Also, the receiver is shown installed in the truing collar to give you an idea as to how it’s held. This bar was manufactured for me by Dave Kiff at PTG and is ground, heat treated, stress relieved and ground once more to the final diameter. Now, here’s the first deal.

When a receiver is indicated in the lathe we have to use the bolt raceway as the standard. This particular receiver was very straight to start with but, the ID of the front receiver ring was .7015” and the ID of the rear receiver ring was .702”. I’ve seen some receivers that measured .701” in the front ring and .705” at the rear ring. With some receivers having different raceway diameters I feel that the only way to truly indicate off of the bolt raceway is to use tight fitting bushings in the raceway. These bushings have an ID of .500" and use the .500" ground rod to indicate off of. This rod must also be hardened and stress relieved, if not, in time it will start to move around loosing its straightness. This first step will dictate the quality of the truing job.

It's imperative that this first step of the process be taken seriously and indicated as close to zero as possible. The machining that follows will dictate whether or not that the receiver threads are concentric and the lug abutment faces and receiver face are perpendicular to the bolt race way. This is very crucial to accuracy.

The next pictures show me indicating the truing collar in and the receiver after it was indicated in to .00005”. Since the collar was made to close tolerances, the truing fixture has to be indicated first so the receiver can be indicated after it’s installed in the fixture.

The next picture shows the receiver face with a very light (.0005”) facing cut to it. Using either Die Chem. Blue or a Blue Sharpie pen you can see the low spots left after machining. Here, on the receiver face, you can see the low spots left blue and high spots cleaned up. It only took a facing cut of .0015” to get the clean up cut you see.

The next picture shows a small boring bar I use to remove taper if any to the crest of the receiver threads and to make a clean up facing cut to the lug abutments. There is a before and after picture showing the cuts made, very light cuts are used. Prior to cutting, I touch off on the lug abutments with the boring bar with the lathe turned off. I set a travel dial to zero after I establish the correct depth and feed by hand very slow until I reach that zero. I then make a facing cut on the lug abutments with a very slow feed.

The next pictures show the threading tool and threads after clean up and a completely trued Remington 700 receiver. In previous pictures you may be able to make out the chatter marks in the threads from the factory threading process. The threads are now smooth and chatter free. I also cut a small relieve groove in the receiver threads at the front of the receiver, this helps me measure the major thread diameter in the receiver and helps me establish an OD for the barrel tendon prior to threading. The threads in this receiver cleaned up with a major diameter of 1.0735".

The following pictures are of the bolt truing process. First, I remove the ejector and firing pin assembly from the bolt body and screw a fixture into the rear of the bolt to hold it in the lathe. I then place a small cat head that I made on the bolt face and line it up in the dead center with grease in the center hole to keep the cat head from galling to the dead center. I also check the center of my tooling to the part after it's indicated in. This is crucial to a good finish on the part being machined. The tooling is adjusted until the machinist scale is leaning out on the top half, this lets you know the tooling is just a tad below center. The bolt body is then indicated in at two contact points and the truing cuts are made.

Next, I set up to make truing cuts to the rear of the bolt lugs. I do so by placing the cutting tip of the tooling against the part to be cut and use a travel dial set to zero. The travel dial is stuck to the bed ways and reads against the carriage. This lets me just touch the part without taking too much material off. You just want a clean up pass.

Next, I set up to make truing cuts to the front of the bolt lugs, bolt nose and bolt face. While the lathe is running at 70 rpm I adjust the steady rest rollers to just touch the bolt body and spin the rollers while it is being held in the first set up. You just wan t enough contact between the rollers and the bolt body so movement is eliminated during the truing process. Again, the travel dial is used so no more metal than needed is removed.

After truing cuts were made to bolt lug fronts and face

I then change tooling to cut the bolt lug faces and bolt face. The tooling I use for the bolt face is a piece of Rex95 Tool Steel I ground to make these cuts. Very light cuts are made, you just want a clean up pass.

This is the completed bolt after truing. I feel so strongly about the benefits of truing a receiver and bolt, I wont even barrel a rifle with out it unless I do it or it's already been performed by someone else.

This receiver is now ready for a match grade barrel and chambering.