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Blueprinting and accuracy improvement - any proof?

http://www.huntingpictures.net/photo/019318
http://www.huntingpictures.net/photo/019316
http://www.huntingpictures.net/photo/019317
Here you go this should put to rest how a Remington looks from the factory. This came from a very accurate .243 Winchester. The action was trued and rebarreled to 6BR at which point it would no longer shoot over 1/2 MOA with any load it was fed. I know this only fuels the ..but...but...but..etc. There are a lot of milling marks or sander marks whatever on the face of a Remington action. On close inspection it looks like an 80 grit belt has been played on the face of this action and all the others I have seen broken down. Judge for yourself.
 
guys companies can not afford to do precise work on actions or rifle barrels and still mass produce rifles to make money . when i disassemble i check each action before i machine them for what is acceptable and what has to be machined . i would like to say that i find one procedure consistantly right but i do not . that is not to say that everthing is bad . but no threads seem to be misaligned all the time . The Rifler
 
The big factories do not run like small shops. There are stations which only do one operation. For example, on an AR15, there is a gang drill which comes down and makes all holes at once. Setups are never broken down for the next operation. They can do precise work quickly because the machine only does one thing.

I just pulled apart a Rem 700 .223. Here is what the face looks like:

It appears to be surface ground.

rem700.jpg


Link to larger photo: http://img688.imageshack.us/img688/9849/rem700.jpg
 
Sir,
I don't think you are qualified to say it is surface ground. It sure doesn't look surface ground to me. I have been in a shop or 2. As Boyd stated above, any receiver custom or factory will have to start with a true reamed bore. A fitted mandrel will be used to indicate the bore. The face of the receiver and lug abuttments are cut at 90deg. from the bore. After this the receiver threads are cut. This is all done in one setup to eliminate tolerance stacking. To take advantage of this work you need a custom bolt body or a bolt that has bushings fit to it. You can set the bolt up in the lathe and cut the bolt face and the front of the lugs and also true up the back of the lugs. You need a person[Dans40xc] that understands timing to install your bolt handle or factory one. It really helps to bush the bolt face to .062 and turn down the firing pin to fit. You can order a PT&G bolt that will have this already done except installing the bolt handle. If you really want it to be comparable to a custom, you will need to machine and install an external bolt release and flute your factory bolt. I highly recommend fluting a tight fitting bolt if you use it in a hunting situation. This will cost you about $750 on top of the cost of your donor receiver. Anything less than that is just a cobbled receiver.
Butch
 
Well I have run surface grinders a few times. And I have a stereo microscope which is good for tool mark analysis.

The work you are saying is a good way to be sure, but I wish I knew in what percent of the cases it made a difference.

I will use a depth micrometer and do some checking.
 
Speaking of mandrels, from what I have seen, they are not as you suggest, but rather made to a very tight fit for the particular actions dimensions. Also, while the mandrel is in the action and supported at both ends, or protruding from the front of the action, it is in the way of measuring or recutting the threads. It is used as part of the setup procedure for aligning a receiver accurately to the CL of its lug raceway within an action truing jig. Depending on the jig, the mandrel is either removed or retracted to a point where it is to the rear of the lug abutments. This is a link to some good pictures on how it can be done.
http://www.bryantcustom.com/articles/true.htm
 
Still makes me nuts when I see a guy on his Grizzly lathe trying to fix what is probably perfectly good threads without even having a way to know if they are out of spec. I will give the PTG system a try before seeing if I should use my lathe for any of this.
 
A friend has a rifle that went through the hands of several gunsmiths before I put him in touch with the right people. Previously, it had been rebarreled by a well known maker of benchrest barrels, and been stocked by a fiberglass stock manufacturer. No thread work was done. It had kept him running in circles trying to repeat an occasional respectable group, but it was not consistent. I did a little research and found a gunsmith to do the action work and barreling. He did a full action job including single pointing the threads and sleeving the bolt. It was rebarreled with a top grade barrel in 6BR. The smith reported that the threads had to be opened .025 in diameter to fully clean up. The other issue was the stock. It was a full shell style that had been bedded without pillars, by the manufacturer, and when tightening the tang screw, it felt like there was no real stopping place, like you could just keep tightening. Eventually this stock was replaced with a McMillan HBR that was properly pillar bedded. The difference was remarkable. Another friend who spent a lot of time and money chasing his tail, trying to get a custom barreled .204 to shoot found that his threads had to be opened up even more to get them to clean up. After they were recut, he set the barrel back, and the gun shot remarkably better, with one of the same barrels that he had used before. Neither of these fellows are inexperienced reloaders. They both shoot well. The reason that I bother telling you the stories is that the set you are buying is expensive, aind neither of the above examples would have had their threads cleaned up with the tap sizes that are available. (to my knowledge) Please read this thread. I think you will find the information on point to your concerns.
http://benchrest.com/forums/showthread.php?t=49577&highlight=action+threads
 
After removing that barrel and seeing how tight it was I would not be surprised if just putting it back at a lower torque would make some difference. Is there some portable barrel vise which just grabs the barrel without having to tighten multiple bolts?
 
The depth micrometer arrived. It reads to 0.00005.

I measured the depth to each locking surface from the receiver face. The micrometer never indicated from than 0.00005 variation.
 
rsilvers said:
The depth micrometer arrived. It reads to 0.00005.

I measured the depth to each locking surface from the receiver face. The micrometer never indicated from than 0.00005 variation.
Click to expand...

The two locking surfaces indicated the same dimension within 50 millionths?
 
If you know how to measure, which I have no reason to doubt, you have established two things, that, in this one case, Remington has held incredible tolerances, and that the front of the receiver seems to be parallel to the lug abutment faces (at least at the points measured). Of course this tells us nothing about how the threads are positioned, or whether the face of the receiver is perpendicular to the CL of the lug raceway. It would seem that that would require a lathe, unless you can relate the specifics of a procedure that will allow you to make these important determinations without one.
 
I realize the mic is not accurate to 0.00005. I never said it was. It only reads out to that level. I was merely reporting what it indicated.

I just finished 'blueprinting' the action with the PTG reamer set. I had 5 bushings in 0.0005 increments and I used the tightest fitting one which would go in. I also changed over the screws to 8-40.

I will shoot it tomorrow.
 
Did you cut the threads oversize? Could you see evidence that they cleaned up uniformly? Good luck at the range.
 
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