fnlights
Well-Known Member
Yep that makes sense. I have just been deciding on going 26, 28, or 30 inch steel barrel for my next 338 Term build and think I am going to go with a 26 or a 28.
Finding the perfect barrel length
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As I noted, it was not what MDT was trying to do.
Yes, I understand it wasnt their scope, just saying it would be very interesting.
What the data from Varmintal seems to say is that in checking group size with bbl length, the harmonics of the system seem to outweigh to a large extent the optimum load development at each length, crown or not.
Length seems to matter most.....ie, whipiness, harmonics. etc.
Yes, because of rigidity.
That really depends on what you want. If you just want to reach out go at least 30. If you want to hunt with it 30 is a little cumbersome especially with a brake.
fnlights
Well-Known Member
Yep great point. It would be strictly a hunting rifle! Agree that 30 with a brake could be a bit much to be carrying. I believe you have actually mentioned that in your post when you were selling your 338 Term.
"It's a 88 magnum it shoots through schools"
Johnny Dangerously
Johnny Dangerously
Hugnot
Well-Known Member
My favored barrels are #5 - #6 contours & 24-26 inch long, .224 to .308 bore - they appear to have a combo of good vibes., less blast & higher velocities but are not easy to lug around.
I would avoid a #1 contour of 24-26 inches in any caliber.
I would anticipate an eventual drag effect with length. Accuracy would be affected by attaching barrels together with machined threads if the axis was not exactly common. I did not see any mention of crowning the barrel after each cut. It was mentioned that inner reflections were observed, these might have been interference rings (optical phenomena) and would indicate barrel was clean for 1st shot which would in turn affect velocity (shown by spikes in graph) & accuracy - if the barrel was cleaned after each cut.
Observe a Palma match with .308W, 155 grain bullets & 30-inch-long barrels having a "Palma contour". My thinking is that barrel contour affects accuracy and practicality affects barrel length.
Run the test again with a 36-inch-long, single unit, fat tapered barrel cut off in 1-inch increments & carefully recrown after each cut. Bed action & barrel shank as a single unit using tough steel reenforced epoxy. I think accuracy would reach an optimum level at some point, but velocity would reduce at different rates depending on amount & type of powder.
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I would avoid a #1 contour of 24-26 inches in any caliber.
I would anticipate an eventual drag effect with length. Accuracy would be affected by attaching barrels together with machined threads if the axis was not exactly common. I did not see any mention of crowning the barrel after each cut. It was mentioned that inner reflections were observed, these might have been interference rings (optical phenomena) and would indicate barrel was clean for 1st shot which would in turn affect velocity (shown by spikes in graph) & accuracy - if the barrel was cleaned after each cut.
Observe a Palma match with .308W, 155 grain bullets & 30-inch-long barrels having a "Palma contour". My thinking is that barrel contour affects accuracy and practicality affects barrel length.
Run the test again with a 36-inch-long, single unit, fat tapered barrel cut off in 1-inch increments & carefully recrown after each cut. Bed action & barrel shank as a single unit using tough steel reenforced epoxy. I think accuracy would reach an optimum level at some point, but velocity would reduce at different rates depending on amount & type of powder.
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Yes, in .338, the longer and skinnier the bbl the less accurate it will be. But for hunting, and carrying especially in mountains weight is very important and likely some accuracy and some velocity will need to be sacrificed at the altar of handling and practical use in rough terrain.
Id try for a 24 inch bbl. with total weight no more than 8lbs. before scope, and live with the velocity and accuracy that gives you. Big magnum calibers have to be heavier I think to compensate for more bbl length
ie, heavier diameter, more rigid
You might get very good accuracy from 24 inches with less bbl diameter, and less weight and sacrifice some velocity.
In "Old Style Safaris" you had a coule of gunbeareres. I hope these 6' rfiles come with a pairI cant wait for all the 6' builds to start showing up in the mountains
Another reason that barrel length likely outweighed the importance of powder or bullet selection, ie, load development in this example was that the whole premise of good grouping is dependent on which way the barrel is pointing at bullet exit timing. This is true for OCW theory, and its true in all the FEA analysis Varmintal has done at varmintal.com
So finding the length of the barrel on the system on your rifle that gives you the least whipiness, and most consistent barrel pointing position at the muzzle at exactly the bullet exit timing is what gives accuracy or good groups. You can on the margin affect bullet exit timing with load development, but compared to the barrel length the contribution of the ammo is fine tuning or its "on the margin", not the major contributing influence.
VarmintBob
Well-Known Member
I pick the "perfect" barrel length for whatever bullet I want to shoot in a rifle under what conditions using Quick Load. I did not read the article since I can't imagine what would be in it. There is no such thing as barrel length vs "accuracy." You can get precision groups from any length barrel. But if you want to optimize something like a 53 gr Vmax in a 22-250, some barrel lengths don't buy you any extra velocity due to the quantum nature of precision barrel times.
If you design with right specs, ie, longer barrels heavier and more diameter and design the bolt and system right yes you can get good accuracy.
But a long skinny barrel will generally have more whipiness, more harmonics, and less accuracy, especially in magnum calibers.
