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Sporter barrel as accurate as heavier barrel?

My experiences confirms that accuracy of a sporter is as good as targets for the first few rounds. I only test up to 5 rounds quickly for hunting purposes. I also think powder burnt and heat have a lot to do with it as well. I have a semi custom 6 Dasher on a 24" #1 barrel and a 5 round mag dump shoots 1/4 MOA. My factory .243 and 7 RM in sporters are only good for 3 to 4 rounds. I have a full custom 338 NM with a #6 that doesn't have a POI change for a 5 shot group. I also have 6.5 SAUM in a #4 and it seems to do a 5 round group just fine.
 
This is an area I feel I have quite a bit of experience since I build and shoot both BR rifles and hunting rifles at 1000 yards for group. The sporter barrels will shoot very close to as well as the heavy barrels when perfectly in tune. Your load will change with temp and humidity and the heavier barrels have less amplitude in the vibration pattern. So as they both go out of tune the heavier barrels do it less dramatically than the sporters. Many confuse this with a wider load window, they both go out of tune the same amount its just thinner barrels will produce larger groups than heavier barrels at the same amount of tune error. The nodes will be just as far apart in the two contours, so tune widths are equal. At 1k an out of tune sporter can shoot real big in a hurry. I really wish more guys would shoot paper at those ranges. Moral of the story, go with the heaviest barrel you can stand to carry, or plan to stay on top of the tune really well.
 
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nksmfamjp said:
Logically, I can see heavier and shorter barrels are more accurate as the amplitude of their vibrations will be smaller for the same load and gun. On top of that, the load will be tuned to a consistent release point in the vibration. ....but if load tune is slightly off as it surely always is, then the smaller amplitude causes the actual POI to be closer to the nominal POI.

Now with the longer thinner barrel with the same basic load, it will have greater amplitude. This means the nominal poi could be the same. If the load is tuned better for this barrel, or both are tuned to nominal, then poi is the same. With tuning error, the thicker/shorter barrel will always be more accurate.
This is really just an untested hypothesis. Wish I had the money/carear to test!
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Actually it has been tested. Look up optimum barrel time. Or obt. There was a pretty healthy debate on some of the target forums at the time. The hypothesis was that by changing coal or powder charge you were basically changing the timing of the bullet exiting the muzzle. With each barrel there is an optimum point in vibration for the bullet to exit that creates the same poi. Guys were even taking a known good load and calculating the barrel time in ms and
trying to duplicate the barrel time with another powder etc. fascinating stuff. If you've ever seen high speed video of a barrel as it is shot it will blow your mind how much vibration there is.
 
You guys can prove the amplitude is smaller with heavy barrels very easily. Make up a target, a horizontal line with aim points along it. Shoot one shot (if you have a good rifle) or 3 shot groups at each aim point, going up in powder charge each time. You will find the thinner barrels will have move vertical deviation from the center line than the heavy barrel covering the same loads. You will also find accuracy nodes will be spaced the same however.
 
Alex, I basically do this when I do my first pressure workup test with a new gun. I map all the POIs and find the node. One more trip out to 500+ yards for a ladder test and its basically done!
 
Plot twist: I took the 7mmRM out to the range today with a different ammo (finally able to find one!) And it shot decently. About 4.5" groups from the previous ammo dropped to about an inch and a quarter with this.

Because of a previous plot twist I havent told you about (I rear ended a nother car), looks like my fun funds are involuntarily being converted to adulting funds to pay my copay.

I am going on a hunting trip this weekend and itll be the last time I'll need my 270 to be sighted in for the season. I'm going to take it's B&C stock with full aluminum bedding block off and put it on the 7mmRM to see what groups are like with it.

I don't suspect itll drop the group size enough, but it's worth trying. Thinking today at the range about Shane's comment about how important confidence is in your equipment and also a little help from Alex Wheeler, it's starting to make sense to buy the heavy sporter . I carried my 270 around today (also heavy sporter) and it really wasnt that bad. I'm not even 40 yet - I'll be fine and I've got time to train.
 
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I think others have said similar but yes. They can be just as repeatable/consistent but cartridge selection becomes a bigger factor. A straight 1.250 contour doesn't really care what caliber it is. A fluted sporter however is going to heat up much faster shooting 338 RUM than shooting 22 PPC. You've got more powder, which is more potential energy, more speed and more bullet surface area that leads to more heating due to friction, and less thermal capacity in the barrel mass due to the larger bore diameter. Problem is you want the bigger cartridge in the hunting rifle and no one likes 25lb hunting rifles so we have to make compromises
 
rustyshackleford said:
I think others have said similar but yes. They can be just as repeatable/consistent but cartridge selection becomes a bigger factor. A straight 1.250 contour doesn't really care what caliber it is. A fluted sporter however is going to heat up much faster shooting 338 RUM than shooting 22 PPC. You've got more powder, which is more potential energy, more speed and more bullet surface area that leads to more heating due to friction, and less thermal capacity in the barrel mass due to the larger bore diameter. Problem is you want the bigger cartridge in the hunting rifle and no one likes 25lb hunting rifles so we have to make compromises
Click to expand...
Nailed it.
 
Accuracy won't be affected. Accuracy is based on the load/tune that you have. With a thinner barrel you will see faster heat transfer to the outside of the barrel due to lower mass and heat capacity of the steel. Will it make it less accurate? No unless you want to do long strings and then you will see a shift in point of impact due to the barrel heat. The reason you see competition shooters with heavy barrels is they will be able to"absorb" 5-10 shot strings in a short amount of time due to the extra steel and with the weight they absorb recoil better and tend to hold on target easier. The majority of competition have the rifle supported by an object ( f-class, benchrest, PRS) so weight is a bonus. Free hand shooting and hunting you want that sweet spot weight that sits in your position. Which tends to be lighter, under 10pounds for the system
 

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