Custom Actions - How Do They Enhance Accuracy?

[JRS]

I seriously doubt an action is going to bend from the weight of a barrel. If it did bend, the bolt would cease to move.

 

[dcali]

I seriously doubt an action is going to bend from the weight of a barrel. If it did bend, the bolt would cease to move.

It absolutely does bend. Not very much, but it does - how else would the muzzle move? It's not the weight of the barrel that does it, though, it's the several thousand pounds of bolt thrust.

 

[JRS]

It absolutely does bend. Not very much, but it does - how else would the muzzle move? It's not the weight of the barrel that does it, though, it's the several thousand pounds of bolt thrust.

The muzzle moves because the barrel is whipping. Most actions are overbuilt for strength.

 

[dcali]

The muzzle moves because the barrel is whipping. Most actions are overbuilt for strength.

But how does the barrel start whipping? In part, because the action isn't perfectly symmetrical, and it bends under an axial load. You can measure it. Vaughn did this with strain gages, and detailed it in his book. The action bends, and helps drive vibration. That's not a guarantee that a custom will be better, but differences in actions can be shown to matter.

 

[JRS]

But how does the barrel start whipping? In part, because the action isn't perfectly symmetrical, and it bends under an axial load. You can measure it. Vaughn did this with strain gages, and detailed it in his book. The action bends, and helps drive vibration. That's not a guarantee that a custom will be better, but differences in actions can be shown to matter.

Once the breach end of the barrel is screwed into the action, it is fixed in space. The barrel then becomes a cantilever objet. The vibration is introduced into the barrel via the enormous pressure from the cartridge being fired, not from the action moving.

 

[Phil3]

What more do you need?

Ray

The answer to my question.

I asked, "I just want to know HOW "overall concentricity" affects accuracy". The responses by damoncali (and JRS), posts number 142 - 146) begin to explain "HOW" an action design can contribute to accuracy issues. That is the kind of info I am looking for. With regards to the Savage bolt lugs being off from one another by .0155", I would like to know just how that impacts bullet accuracy. Not saying it won't, I just want to know HOW it affects the accuracy.

It is obvious I need to read the Vaughn "Rifle Accuracy Facts" book, but cannot yet lay my hands on it. If I can borrow I will, but may need it a while as I understand it is anything but a quick read.

To damoncali: Where did you hear about the Vaughn book being possibly reprinted?

Phil

 

[CharlieNC]

Step 1- accept the fact that a "better" action can provide improved accuracy.
Step 2- accept the fact that those who have earned a sterling reputation for building and truing actions know what is important. Trust them to know what to do for you.
Step 3- focus on what you can do as a loader and shooter to get the most out of what have. Once you are sure you have mastered this step, see step 2.

I am currently stuck on step 3.

 

[bigstick6017555]

I think some people are using this as a gotcha question to stir up the troops, which appears they have done a good job, or just for something to throw against the wall and see what sticks. these people seem to be very knowledgeable on guns and the workings of them, and this is why I am kind of reserved on the basis of this questioning. a question like this seems to be on the same level as asking what makes handloads more accurate then factory ammo. down thru history it has been proven that any machine, and I mean any, (and a gun is a machine) that uses better tolerance's, materials, and workmanship , will always perform well above its counterpart in the long haul. it may not be what you want, or need ,or willing to pay for, but precision is about removing all possible variables and a guns action is a variable plain and simple. want more proof, watch the aggregates of competitions and compare them to equipment used.
if tolerances, material, and workmanship mean nothing?, why would a race car need or want anything more than a stock factory engine of horsepower desired.

 

[dkhunt14]

I think the Op had in his mind all along he wants to use a Savage and the cheap way out. There were a lot of guys with lots of experience telling why they were better but it seems the OP doesn't want to hear it. Guys have tried different actions, calibers and everything imaginable to win. When it comes down to it all you have to do is look at the equipment lists to see what wins. In BR and a lot of other games the custom wins because it is more accurate. Better machining, beter ignition and all around better. Asking the question how do they enhance accuracy is like asking why or how a certain powder works better then another one. Matt

 

[Phil3]

Step 1- accept the fact that a "better" action can provide improved accuracy.
Step 2- accept the fact that those who have earned a sterling reputation for building and truing actions know what is important. Trust them to know what to do for you.
Step 3- focus on what you can do as a loader and shooter to get the most out of what have. Once you are sure you have mastered this step, see step 2.

I am currently stuck on step 3.

I think some people are using this as a gotcha question to stir up the troops, which appears they have done a good job, or just for something to throw against the wall and see what sticks. these people seem to be very knowledgeable on guns and the workings of them, and this is why I am kind of reserved on the basis of this questioning. a question like this seems to be on the same level as asking what makes handloads more accurate then factory ammo. down thru history it has been proven that any machine, and I mean any, (and a gun is a machine) that uses better tolerance's, materials, and workmanship , will always perform well above its counterpart in the long haul. it may not be what you want, or need ,or willing to pay for, but precision is about removing all possible variables and a guns action is a variable plain and simple. want more proof, watch the aggregates of competitions and compare them to equipment used.
if tolerances, material, and workmanship mean nothing?, why would a race car need or want anything more than a stock factory engine of horsepower desired.

I think the Op had in his mind all along he wants to use a Savage and the cheap way out. There were a lot of guys with lots of experience telling why they were better but it seems the OP doesn't want to hear it. Guys have tried different actions, calibers and everything imaginable to win. When it comes down to it all you have to do is look at the equipment lists to see what wins. In BR and a lot of other games the custom wins because it is more accurate. Better machining, beter ignition and all around better. Asking the question how do they enhance accuracy is like asking why a certain how a certain powder works better then another one. Matt

It is beyond astounding that a simple post could be so wrongly interpreted and gone off in so many bizarre directions. As the post title says, all I wanted to know was how a custom action enhances accuracy. Nothing more, regardless of what anyone else thinks, theorizes, or believes in the way of my motivations (i.e, rationalize Savage actions , etc). All of that nonsense does not change the truth...I just wanted to know how a custom action enhances accuracy (steers the bullet more accurately), end of story.

In post #150, the poster writes, "...if tolerances, material, and workmanship mean nothing?, why would a race car need or want anything more than a stock factory engine of horsepower desired....". I never said tolerances, material, and workmanship mean nothing. My solid knowledge in building race car and motorcycle engines may be out of date now, and I often followed "accepted" practices to make more power, BUT, I always sought to understand just how and why such accepted practices actually resulted in more power. People may wrap exhaust pipes in heatproof and insulating fabric to make more power, an "accepted" practice, but I had to know how such a mod resulted in more power, not that it just "did". That allowed me to build upon accepted practices and make further improvements, which served me well.

Is asking how a component, or a modification, actually improves performance so wrong? For some, apparently so.. One poster writes, "...Asking the question how do they enhance accuracy is like asking why a certain how a certain powder works better then another one..." (poster's English, not mine). This was not written in a complimentary way (see post #151). Why not ask that? The answer may not be important to some and that's fine, but I'd like to understand the how and why of rifle accuracy...much like Harold Vaughn.

Phil

 

[swd]

I think I can simplify all this. Custom actions are more accurate because:
They run tighter clearances.
Parts that need to be square and perpendicular to each other are.
Many have improved ignition over factory actions.
Parts that need to fit properly do fit properly because bean counters arn't involved in the manufacturing process.
Other important tolerances are kept in check.
Please note that not all custom actions necessarily meet the above criteria. But the good ones that do are more accurate than factory actions.
I hope this solves this great mystery.

 

[CharlieNC]

I applaud your interest in the HOW and WHY various specifics work, and I would love to know much more myself. I expect the answers are somewhat proprietary and extremely voluminous, neither of which are likely to evoke answers from those in the know. I would also bet the long list of important features were not tested individually to enable such an answer, but resulted from experience indicating its the right thing to do. Why test the degree of concentricity effects on accuracy vs just make it as right as financially feasible? Perhaps if you were to call a top gunsmith to discuss your interests, he could prioritize the most effective steps for your case.