Basic BlueprintingBy Vickie M. Harrold with S.T.H.
Copyright 2011 Precision Shooting Magazine
“Parallel, square, straight, concentric and true, extreme rifle accuracy lives and dies by you.”
Let’s be honest, all incantational chants, black magic and voodoo aside, if the basic components of any given rifle build are perfectly parallel, square, straight, concentric and true, then producing an exceptionally accurate rifle is an easy task for virtually any competent person. Unfortunately, they rarely are and it almost never is. Actually, in my experience they NEVER are and it NEVER is! This is why most gun-builders have mood-swings of remarkable range and spend a lot of their time talking to themselves. To build the extremely accurate guns people pay us to build, we need every component to be absolutely perfect! But, they never are! Consequently, we spend more time “fixing stuff” than actually building guns. Is it any wonder some of us become just a wee bit cranky? Which brings us to basic receiver “blueprinting.”
Now, just what does this strange word “blueprinting” mean? Well, in the automotive world it means to “totally rebuild an engine to the most precise tolerances possible.” But, in the firearms world the definition is (perhaps intentionally) a bit more nebulous. You see, in reality “blueprinting” is a technically sounding word that many years ago a nefarious “Master Riflesmith” made up so he could pay for his kids’ college education. After all, who wants to pay big money to have their “junk fixed.” It just doesn’t sound like a job that anyone would pay much for.
So, on we go to actually “fixing” (blueprinting) a receiver. Any make or model of mass produced receiver will do because they all need fixing. Yes, it is true that some receivers are higher quality than others. Also, that some are easier to work on and more conducive to exceptional accuracy than others. But, in my experience there seems to be no rhyme or reason between getting a fairly good one and getting a really bad one. Even within the same make, model and serial number run, I have seen the good, the bad and the downright ugly. Consequently, if you desire topflight accuracy from any non-custom, mass produced receiver you should just assume that some machine work will be required.
For this particular article and project, we started with a brand new unfired Remington 700 SPS rifle. Although we are sometimes coerced into working with “used” receivers at our shop, we always prefer to begin with a virgin receiver whenever possible. When you consider that “blueprinting” is basically the act of removing metal, and that only a limited amount of metal can safely be removed, it is best to start with as much steel as you can get. Plus, starting with a new unfired receiver helps avoid any previous owner induced flaws of which there can be many; some non-repairable.
In picture #1 you see the new intact rifle. In picture #2 it has been disassembled into basic components. In photo # 3 you see the tools we typically use to separate the receiver from the barrel; I stress the word “typically” because we use completely different tools when we encounter a “really tight one.”
In photo # 4 both the receiver and barrel have been tightly clenched in our homemade aluminum bar clamps. You will note that sheet lead has been wrapped around the barrel in order to give the clamp more holding power on the steep, short factory contour. Once these bar clamps are in place, the smaller barrel clamp is placed in a large bench vise and tightened securely. Then the beating commences.
Exactly why they employ a highly motivated 700 pound gorilla at Remington is a mystery to me; but, I have found that you can usually overcome his legendary work by striking the receiver loosening clamp both very hard and very fast. That’s VERY HARD and VERY FAST. If you hit it hard and fast enough, “the easy ones” will often separate with just one mighty whack. However, if you are unfortunate enough to get “a really tight one,” well just remember, “what does not kill you makes you stronger.” Yea, right! Nietzsche never had to break a barrel loose from an action, so he shouldn’t be taken seriously here.
In photo #5 our maniacal whacking has been successful and receiver and barrel have been separated. Hallelujah! But, wait, what is this; it appears that there is quite a bit of rust on both faces of the recoil lug? How could a perfectly mated, parallel lug that is sandwiched between two other perfectly parallel surfaces be rusted? How indeed?
Photos #6 and #7 should be self-explanatory to anyone with an IQ above vegetable-level. Just look closely at the photos and repeat the first sentence of this article: “Parallel, square, straight, concentric and true, extreme rifle accuracy lives and dies by you.”
Photos #8, #9 and #10 show our sixteen piece 0.0005" receiver raceway bushing set and GTR - PTG, 0.705" bolt raceway reamer/mandrel/indicator rod. Although this rod/reamer is designed to perform multiple functions, due to the inherent limitations of a magazine article, we will simply be using it as an indicator rod and not a reamer. Note that the tang end of our receiver raceway required a 0.702" bushing and the face end took a 0.703" bushing. This is only a 0.001" difference and it gives us the option of not reaming out both holes to 0.705" if we so choose. A discourse on bolt and raceway diameters/relationships would be appropriate here, (also trued factory bolts -vs- aftermarket custom) but we simply do not have the time or space. Just try and match the two as close as possible while still allowing them to function properly. Too tight is worse than too loose; believe me.
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