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How far back from muzzle to stop taper, for highest accuracy?

 
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Old 09-10-2013, 03:29 PM
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How far back from muzzle to stop taper, for highest accuracy?

I have a 32" barrel on order that will taper down to 1.00" at the muzzle (from 1.20 at the chamber). But it looks like I have the option to terminate the taper at some point BEHIND the muzzle, going straight cylinder (NO taper) to the muzzle from there. I'm thinking somewhere between 1, and 2 to 3 inches max?

The length that best dampenss out the harmonics Is what to use, I presume. Too long taper setback, it that's what to call it, will result in some stiffness lose though.
But I don't have even the slightest idea. Highest possible accuracy is the goal. Any ideas on what "setback" length might yield the highest accuracy potential?

Is there anyeasymethod to "calculate" the optimum value for this paticualar dimension? (It is 0 right now, but I don't think that is optimum.)

Cal is 7RUM w/9 twist, & muzzle will have 11 degree crown, WITHOUT a brake. Due to the backlog, I should still have plenty of time in which to make changes to the order.

Last edited by Max Heat; 09-10-2013 at 04:38 PM.
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Old 09-10-2013, 05:14 PM
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Re: How far back from muzzle to stop taper, for highest accuracy?

The "best" is no taper. Why not keep it straight parallel couture from breach to muzzle? Sounds like you are planning on minimal taper anyway, so why not just keep all the material there.
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Old 09-10-2013, 06:08 PM
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Re: How far back from muzzle to stop taper, for highest accuracy?

Quote:
Originally Posted by Fergus Bailey View Post
The "best" is no taper. Why not keep it straight parallel couture from breach to muzzle? Sounds like you are planning on minimal taper anyway, so why not just keep all the material there.
With NO taper it will exhibit a stronger tendency to resonate, which is presisely what I wish to eliminate, as much as possible That's why THAT apporach doesn't go over so well with me..
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Old 09-10-2013, 06:36 PM
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Re: How far back from muzzle to stop taper, for highest accuracy?

I thought you wanted the best accuracy, not a theoretical discussion.

My answer is based on actual results in competition in both short range and long range matches over 12 years.
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Old 09-10-2013, 07:02 PM
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Re: How far back from muzzle to stop taper, for highest accuracy?

You have a point there. Are you saying that a straight 1.20" cylinder will ALWAYS [noticably] trump out, over 1.20 to 1.00" taper, when it comes to accuracy?

If so, I do need to give that option serious consideration.
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Old 09-10-2013, 08:27 PM
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Re: How far back from muzzle to stop taper, for highest accuracy?

Short answer, I think there is a very strong body of evidence that a straight taper is a better option from an accuracy perspective. You need to bear in mind here though that in ultimate accuracy, there are a lot of different, incremental elements that all lead to accuracy. Its not as if you can isolate any one of these variables and see an immediate difference on the target (at least in many cases - some are obvious". So I cant guarantee you a "noticeable" improvement - just a better chance to shoot accurately and maintain an accurate tune.

When the cartridge in a rifle is detonated, there are a lot of forces at work, and no barrel contour is going to eliminate these effects. The best you can hope to do is minimise the vibrations and tune the best that you can. I believe the straight taper is the best outcome for this.

I shoot a lot of short range benchrest, and in may classes, a barrel taper is required under the rules. However in unlimited (as the name of the lass suggests), there is no limit on the barrel taper. If you take a look at an unlimited barrel, you will see 99% of entries in the class have a straight taper. Likewise in F Class and long range BR where there are no contour restrictions, the vast majority of competitive shooters will be running a straight taper.

Like I said earlier, based on my shooting, and discussions with very accomplished shooters, a straight taper is a better, more consistent, option than any taper. Its just a matter of whether your circumstances (eg governing rules in a competition environment - or equipment & tactics in a hunting environment) allow its use.
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Old 09-12-2013, 12:04 PM
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Re: How far back from muzzle to stop taper, for highest accuracy?

Thanks, mate! An american yankee redneck bloke like me doesn't normally use words like that, but I want to convey how much appreciation and interest I have in what you have to say.

Since it will not be a pure BR rig, being taken "afield" quite frequently, I think I will stick with minimum taper. But I still haven't heard any suggestions on how far back from the muzzle to end the taper . I'm thinking 2.25". But that's basically for no other reason or rhyme than looks, aside from trying to avoid having it be a dividend of the overall length. Especially a low, even dividend. I'm try to avoid getting too technical, like I frequently do. But with ANY taper it is very difficult, without having to solve complicated differential equations, to come up with a solid [mathematically proven] solution for the optimum setback # that I wish to go with.

I'd like to know more about BR rules and regs though, since I'd like to try my hand at it some time soon. I'd like to start out at around 3hun, then maybe move out to 6. Are there any "standardized" BR classes out there that are NOT open to the straight taperers, but ARE open to a 32 or 33" barrel, with 7RUM chambering? P.S. - Overall weight will probably be between 20 and 22lb..

Last edited by Max Heat; 09-12-2013 at 12:19 PM. Reason: forgot something
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