quote:

Originally posted by jørgen:
Hi Bill
That was an exelent post, pretty objectiv describing some of the factors in "bluprinting"

Now i would like someone to come foreward with the results of all this efford. And what is the tecnical problem not dooing it.(no interest in the term "poor accuracy") moer the reason for it.

That must be something for Malm to comment after promoting "bluprinting" so heavily.

As I said before, I know of no testing done which illustrates the effects of given errors. In fact, most evidence I'm aware of is anecdotal only. However, some seficiencies which might exist in an action do have a demonstrable effect on either accuracy, function or both. An example is a bolt face which is not perpendicular to the bolt body. This can cause case stretching which reduces case life. It can cause difficult bolt opening and it can affect accuracy.
A realistic test of the effects of various deficiencies could be done but it would be fairly involved. I would do it something like this:
First I would either start out with a 40x action or I would procure a good custom single shot action. I would then bore the threads out to 1 1/8x20 tpi. At the same time I would do every thing I could to be sure the receiver was as good as possible. I would make a bolt with interchangable head (like a Savage). I think I would use a 30 cal chambered in 308. It is accurate enough to give real results and is a true hunting caliber as well as a proven target cartridge. I would make the barrel reasonably heavy. Probably a heavy Palma contour but cut to 24".
I would start by fitting the barrel conventionally to the nicely true receiver and, Having worked up a decent load, fire five, five shot groups using my best BR technique. This to establish an accuracy baseline. Then, I would make a threaded bushing to screw into the receiver. This bushing would be made with an internal thread of 1x16tpi and the threads would be straight and concentric. The barrel would be rethreaded and fitted to the action with the bushing in place. Another series of five shot groups would be fired to verify that accuracy was as good with the bushing as without. I think it would be.
Then the action would be set up crooked and a facing cut taken on the front of the bushing. This would mimic the receiver with a crooked face. Another series of five groups.
Now another bushing would be fitted but this one would have the internal threads bored and threaded to be angularily misaligned but the face perpendicular. Another firing test. Then this bushing faced so that the face is perpendicular to the threads but not to the bore of the receiver. Another test.
The next bushing would be made straight but not concentric. I would offset the internal threads by about .010 (.020 TIR). Another firing test (I personally don't think this one would have too much effect).
Now back to the first, straight bushing which is refaced and shimmed (to correct headspace) and retested to verify accuracy with this combo.
Now changed to a bolt head with a crooked face. then one with one lug touching etc.
This way one could use the same barrel all the way through and not fire somany shots that barrel wear should be an issue. One should be able to get some idea to the effects of introduced variables. As you can see, not an easy task. Also, not an inexpensive one. Don't expect me to do this any time soon! Regards, Bill.

The action is the foundation of accuracy, and just as one wouldn't want to build a house on a crooked foundation, one wouldn't want to build an accurate rifle on a crooked action.

The big question is, how far out is the action, and to what level does one go? If you're having a top grade match barrel fit, you're looking at a materials and labor cost of nearly $500, so to me spending another $100-150 to have the action squared up makes sense, ie to get the maximum benefit of best qualitie components, have precision machine work done to maximize your chances of success.