View Full Version : Free floating a barrel??
February 27, 2011, 11:13 PM
I have been reading on barrel floating and it seems like some say the barrel should be in contact with the stock on the very tip of the stock and others say a dollar should be able to slide down between the two with no trouble. Which is the best and why??? Seems to me like no contact of the stock to the barrel would be the best??
February 28, 2011, 12:51 AM
It depend on the gun. Usually, a heavy barrel prefers to be fully floated while a sporter weight barrel shoots better with a little fore end pressure. That isn't gospel though, each barrel is an entity unto itself. I would free float it first, and then add a small dab at the front of the stock if I felt accuracy could be improved. Also, you have to play with the amount of pressure put on the barrel. Force something between the barrel and stock that will flex the stock or barrel just a little (folded up paper works good). When the bedding dries, it will push a little. You can experiment at the range with shaving it a little at a time to see if shooting improves.
March 1, 2011, 10:42 AM
dawico is correct. It depends on the individual gun.
It has to do with barrel harmonics, or "whip", when the bullet travels down the bore.
Lighter, thinner, more "whippy" barrels sometimes do better with some upward pressure at the tip. How much pressure depends on the barrel and the load.
Heavier barrels usually have less whip, and usually respond better to free floating.
March 1, 2011, 01:44 PM
Generally speaking its best if the barrel is only contacting the receiver at the threaded joint.
Pressure points have been tried and in limited instance work well, but by and large its dependent upon a very rigid set of circumstances.
Take the M-14/M1A for instance. Well known/documented that when building a National Match rifle the barrel/gas system requires a certain amount of preload applied by the stock in order for the rifle to shoot well. Memory escapes me but I believe its in the 12-16lb range.
Try that with an international smallbore gun and you'll have lightening strikes all over the tgt. (meaning it'll never hit the same place twice)
A number of smiths make the effort to bed a barrel for a few inches in front of the recoil lug. This is generally reserved for heavy contour barrels in spaghetti actions. It's in the attempt to mitigate any potential distortion in the receiver from having to support the added mass. (think of petting a cat across its back, it'll hunch up every time and this is what the action tries to do without the additional support)
A pad up front somewhere may work but in limited instances. Change the way you mount the gun when shooting from a bag and it's going to apply more downward pressure on the forend, the point of impact is likely to change. Go prone with a sling and it'll try to move also. Front halves of a stock aren't all that rigid so it'd take considerable internal work on a stock for it to tolerate it enough not to change the loading on the barrel. Essentially this mimics a set of shock absorbers on a car. Changing preload, rebound, compression dampening can have significant effect on how it handles. More/less pressure up front will do the same and may work exceptional, but in a narrow operating parameter.
As I mentioned, in almost all instances your best off to leave it floated all the way to the action and then tailor the loadwork to "catch up with the barrel". That's the beauty of handloading. Rimfire stuff is far more complicated/time consuming. There's no crystal ball to tell you if the gun will behave. It's a function of building it the best you can and then being diligent at the test rig with a good assortment of ammo lots till you literally stumble upon what the gun likes.
Experience has taught me that a well built rifle with good components is far less sensitive. Use the heaviest barrel that still falls within the build requirements, bed it properly, and pay attention to things like the chambering, thread fits, crown, and it'll almost always perform well. I've only had a few in the last 10+ years of doing this stuff that were just cranky and moody.
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