parallel barrel vs taper with a tuner

[AlanF]

Dave,

I had noticed a little more copper fouling than I'd expect with a 1 in 9 7mm, and it appeared to be originating in the first 6 inches of the bore, which coincides with the barrel clamp position. I now compensate for this by paying particular attention to that area with Iosso. However I would not want to do anything like that near the muzzle.

Alan

[DaveMc]

Not a problem so far but I would think constriction at muzzle is better than one at breach.

I get coppering in the firecracking in first 6 inches or so as well.

[Barry Davies]

Alan,
All of our fitted tuner sleeves are fixed with Loctite. Make sleeve 2 to 3 thou over barrel diameter. No possible chance of sleeve causing a restriction at the muzzle.

[Brad Y]

Alan- as part of our discussions while I was having barrel issues, you convinced me to use moly as I was having bad copper fouling from the chamber forward. I now have re built my rifle as you can see without the barrel block- makes changing barrels much nicer! Before the rebuild and rechamber, I tried it without the block with naked projectiles and it still coppered fairly heavy, though I must admit I didnt check the throat with a borescope. Will keep an eye on it and see if the copper is being laid all the way down it now without that restriction. Still going to stay with coated projectiles though.

[BATattack]

Just to clarify if you can Peter -

Are you saying the fixed weights aren't really dampening vibrations - just modifying the frequency (I guess "slower"?) and amplitude ("larger"?) such that energy remains the same?


Adam- Nice way to ask a curly question for sure! I don't think anyone can give you a definitive answer as to which is better yet and you probably have to ask yourself do you want to experiment with it rather than an outright answer? Ultimately it will come down to the individual barrel quality more than the system between these two options. I have both and have seen remarkable results from both. I think the potential for the heavy weight on thinner barrel is to change significantly the tune as Peter outlined above (sorry I have been calling it "dampening") and can give you quite a different outcome to a straight taper stiffer barrel - of course the 32" versions have a slower frequency but larger amplitude vibration compared to short barrels as well but not to the same extent as a thinner barrel with muzzle weight. Both can be tuned to be accurate and both should have wide nodes. I have seen top level rifles in both configurations but theoretically (and seemedly in the real world) the weighted barrels should be slower frequency but larger movement.

There is of course another (potential) type of pulse here called the "P wave" and described in the OBT theory and Varmint Als website where the barrel opens up in a pulse down the barrel. when these waves hit the muzzle it is theoretically like a poor crown. Larger diameter barrels at the muzzle (whether it weight or just barrel diameter) should open up less than small diameter barrels such that "scatter nodes" may not be as severe - that is the theory at least.

Well all the easy questions have been answered Dave! Haha there are so many questions to do with this sport and internal ballistics that have yet to be answered. It may be many years before science can give us a definitive answer to our questions so why not throw them around amongst some experienced shooters and see what comes out of it.

I'm not a scientist or a statistician that will sit down to analyze data or plot a graph but to me the way a heavy weight on the end of a relatively thin barrel works is. . . Imagine attaching a thick rope to a bowling ball. If you whip the rope the rope will move but once the wave reaches the bowling ball the ball will stay stationary and absorb the wave.

The heavier the weight the more it wants to stay stationary. If the weight is attached to the end of the barrel the end of the barrel should move less that what it would without a weight. That's my redneck logic!


Is that more beneficial to accuracy than a barrel that is stiffer for its entire length . . . . .that's the big question I guess?!


So cam's got them on all his barrels, Marty has at least 1? Brad seems to be liking his and I've had good results without one. . . . . Makes it hard to order a new barrel!

[DaveMc]

to me the way a heavy weight on the end of a relatively thin barrel works is. . . Imagine attaching a thick rope to a bowling ball. If you whip the rope the rope will move but once the wave reaches the bowling ball the ball will stay stationary and absorb the wave.

The heavier the weight the more it wants to stay stationary. If the weight is attached to the end of the barrel the end of the barrel should move less that what it would without a weight. That's my redneck logic!

I might be wrong but think it would be better to imagine it like a sinker on the end of a fishing rod.

Also Marty may have them all done now (at least the bulk) and all seem to perform equally well. Think I know of 9/9 success stories but would need to confirm.

[BATattack]

to me the way a heavy weight on the end of a relatively thin barrel works is. . . Imagine attaching a thick rope to a bowling ball. If you whip the rope the rope will move but once the wave reaches the bowling ball the ball will stay stationary and absorb the wave.

The heavier the weight the more it wants to stay stationary. If the weight is attached to the end of the barrel the end of the barrel should move less that what it would without a weight. That's my redneck logic!

I might be wrong but think it would be better to imagine it like a sinker on the end of a fishing rod.

Also Marty may have them all done now (at least the bulk) and all seem to perform equally well. Think I know of 9/9 success stories but would need to confirm.

Yes probably a better example.

Crap . . . . Now I'm gonna need one of each! Haha

[John23]

I have some interest in tuners for some time now.

What I have not been able to determine is if a tuner can be used to skip load development.

hypothetically can one choose a powder charge that will offer a high MV and then simply tune the barrel so that high speed load works in a accuracy node?

From my experience my rifles have always preferred lighter loads if I want them to shoot the best.
Is a tuner a way to have my cake and also eat it?

JH

[IanP]

oops, posted in wrong thread - deleted!

[Brad Y]

John

Im no expert, but would have to say no- you really want to do load development as well with a tuner set to 0 or all the way in to get a baseline. Then when you have got something that is as good as possible then adjust the tuner to change the shape of the group. Tuners are really just a final stage to help shrink what you have already developed- I dont think they compensate for poor grouping ability and high ES/SD. There is alot of info on accurateshooter.com from Erik Cortina on the subject. I followed his load development procedures and have worked a good load that now just needs to be proven. The tuner has adjusted group shape,- what worked at 300m seems to have had a good effect at 800m. However it will be interesting to see if it stays accurate in all weather conditions and across all ranges. I still think there is merit in the heavy weight to increase the size of the accuracy node, whether being able to adjust it or not has merit Im not sure yet. Tuners wont make a bad barrel good, they are advertised to make a good barrel great (if you want to risk tampering with a good barrel). But it is also another factor to introduce that can go wrong. I keep hearing people swearing by them, only to see them removed and guns working better than before. So beware its another factor that might be fun figuring out, but at a prize shoot could catch you out.

Hearing from the national queens about the number of 7mm's that had vertical, I think your best tuning your load without a tuner first. Get the X count up as high as possible. To me a high x count is a sure fire way to tell if a gun is working- and at a national level you can see that if your not getting those 60's with high X counts particularly at short ranges then your behind the 8 ball to start with. If you can get your barrel humming, then leave it. If it goes well but not crash hot, maybe its worth experimenting with as a last resort. If its not performing at all, dont waste your money with it and find another barrel that performs.