Are free floating barrels less sensitive to bullet changes?

R

Roadkill2228

New member
So I've been wondering...are free floating barrels less affected by ammunition differences than bedded barrels? I shoot 3 hunting rifles, a savage 99 in .243, a savage 111 in .270, and a weatherby vanguard in .300 win mag. The .270 is free floating (I made sure of that by taking the barrel and action out and "shaving down" that cheap stock where it was touching against the barrel to begin with), and it's never made me a "one ragged hole" grouping but I have not found a round, factory or reloaded, that it doesn't like and they all hit about the same at 100 yards, maybe a bit of vertical difference but absolutely no horizontal effects. The vanguard and the 99 are both bedded barrels and are both a)much more sensitive to bullet weights as far as accuracy (especially the .300, it hates lighter bullets and loooooves the super long an heavy projectiles) and b) they exhibit not only vertical differences but horizontal ones too (especially the .243, I switched from reloaded barnes tsx 85 brain to federal trophy copper 85 grain, so same bullet weight and construction basically, and their point of aim was about six inches different! At 100 yards about four or five inches sideways and a few inches vertical. Also the federal trophy copper is probably the most accurate round I've shot out of that gun but that's besides the point) So does this have anything to do with my .270s free floating barrel or not?
 
@roadkill: I'm inferring that your question is: Are point of impact changes due to bullet weight/design differences, less pronounced in free floated barrels versus barrels with some forearm pressure? I can't hardly think so, but it will be interesting to see what others say. I believe that the point of impact changes between bullet weights or between bullet designs, are primarily influenced by the gods of the ballistic coefficient, and secondarily by velocity and range.

You didn't mention what specific bullet weight your Weatherly vanguard likes. I have a rifle similar to yours: a S&W 1500 also chambered for .300 Winchester magnum. I've never shot anything lighter than 165 grain, but a 3 shot volley of that weight, groups like a target rifle. 180 grain works equally well. I've been told that with big cases, the heavier bullets exhibit less shot to shot variation.
 
My vanguard groups so-so with 150s, acceptably with 165-180s, and so far it's favourite has been 208 bthp hornady match bullets and 220 grain rnsp hornady hunting bullets. It's abysmal at any distance with 110 grain varmint bullets but I only use those loads within 50 yards for vaporizing milk jugs, rotten produce, an such. At 100 yards ballistic coefficient won't affect much yet, and in the .243s case the muzzle velocity is the same. No, something about the gun, not the cartridge, has to be involved in a different load with the same weight bullet at the same speed hitting 4 inches sideways and 2 inches low, I just don't know for sure what.
 
Yes.

The pressure against the barrel from the fore end is always the same; zero. Zeros on the sights are determined only by where the bullet leaves on the barrel's vertical whip angle, bullet ballistics and the shooting position. All these are small variables.

If the fore end touches the barrel, there's no way it can be constant across all shooting positions. All fore ends bend; how much depends on how stiff they are plus the direction and amount of external forces. That adds a huge and widespread variable to the system.

Fore ends stock ferrule's on match grade M1 and M14 service rifles pull down on their barrels with 20 to 30 pounds of force. Consistant and repeatable holding of their fore ends is more critical to shooting them accurately than with a bolt action rifle with a free floating barrel.

Zeros can change from one shooting position to another. And from one person to another using the same rifle and ammo because each person holds the rifle differently.
 
Last edited:
So I've been wondering...are free floating barrels less affected by ammunition differences than bedded barrels?
Click to expand...

The answer is, well it depends. It depends on what you mean by bedded barrel, and it depends on the barrel.

If the barrel is as close to mathematically perfect in all inner and outer dimensions from steel of uniform strength and density, I can't see bedding the barrel doing much good.

But, if a barrel has a non concentric bore, internal stresses, or other real world imperfections, then sometimes bedding the barrel can produce much more consistent results than free floating the barrel.

Getting back to Garands and M14s, many service members correctly noted that shooting with the sling reduced group size as it dampened barrel vibrations with issued ball ammunition. The trick was to keep the tension as consistent as you could.

To put more variables into play, does using a barrel block and free floating the action count as bedding the barrel? If so, bedding the barrel has produced some extremely tiny groups in centerfire and rimfire rifles. The barrel block provides consitent pressures, and the rest of the system is free floating so it meets the definition of a barrel bedding job.

To put things into context though, I generally try to see how well a rifle will shoot with a free floated barrel and bedded action before I try anything else to decrease group size.

Jimro
 
Using a barrel block and free floating the action counts as a mount for the barrel; the action and barrel parts outside the bedding block are free floated. The opposite's an action bedded solidly and its barrel free floated. I've seen a few fore end block clamped barreled actions that shot very, accurate. So do benchrest and bullet factory (Sierra) rail guns having done so over the years. That block's very repeatable from shot to shot as it holds the barrel. But they've not quite equalled a properly bedded receiver and the barrel totally free of any contact with the stock for hand held rifles shot off ones shoulder.

Garands shot from machine rests always produced better accuracy than anyone shooting them; slung up in prone or off bags of some sort. That's with any ammo used. But they kept the same "grip" on the stock's fore end, too. And no sling at all. Some shot 3 clips of ammo under 2 inches at 300 yards.
 
Last edited:
Roadkill2228, Weatherby® Vanguard® Series 2 rifles are guaranteed to shoot a 3-shot group of .99" or less at 100 yards (SUB-MOA) when used with specified Weatherby factory or premium ammunition.


Friend of mine has Vanguard 300mag and it pretty accurate as is. Before you do anything I'd talk to Weatherby.
 
Great information so far, but I'm still left a little puzzled. I went back and re-read the original post, particularly the title, and the first and last 3 or 4 sentences. While the original poster mentions accuracy, I thought the heart of the question was:

Given: Bullets of different design (and ballistic coefficient), but with the same weight, will have different points of impact and bullets of similar design but different weight will also have different points of impact. Will the point of impact changes be less with a free floated barrel or with a non-free floated barrel? There are no other variables to the question.

I don't think that question has been totally answered. But perhaps, I'm mis-interpreting the question?
 
Last edited:
Yes.
It's my opinion that for bolt action rifles, well fit receivers in the stock and the barrel totally free floating in the fore end, best accuracy with any load will happen. That was the rule before epoxy bedding receivers happened. So bedded, accuracy is better.

If the receiver is poorly fit to the stock, accuracy may improve with some pressure on the barrel, but zeros will vary with position and stock warping from atmospheric changes. Whether or not that's apparent depends on ones marksmanship skills and the inheirant accuracy of what's shot.

If accuracy is the reduction of all variables to, or as close as possible to, zero, why put another one in the shooting system? Bedding or pressure pointing the barrel is a variable.
 
Last edited:
Bart B.,
That block's very repeatable from shot to shot as it holds the barrel. But they've not quite equalled a properly bedded receiver and the barrel totally free of any contact with the stock for hand held rifles shot off ones shoulder.
Click to expand...

I'll just put this here: http://www.6mmbr.com/gunweek075.html

Yes I know that is a benchrest rig, not an off the shoulder rig. But we are talking accuracy here, not what is most accurate in which competition. And as Bart has already noted, accuracy for loads are tested on barrel blocked accuracy test actions because they are more accurate than normally bedded barreled actions.

Jimro
 
First time I saw a fore end block holding a barreled action on a stock made for off-shoulder firing was around 1970; they are nothing new. My reference to barrel blocks in rail guns was to Sierra using them to test bullets, not loads. Sierra uses the same load for each respective bullet; they don't work up loads for each lot of components.

The rifles in that link are shoulder fired F-class ones. And 6mmbr messed up distances again; 300 meters equals about 328 yards, not 345.
 
Last edited:
Oh wow thanks for the replies guys. Hammie, you fully understand the question - not asking about the overall potential for tight groups, simply asking if point of impact changes are more drastic when switching loads in barrels that are not free floating. Bart B thanks so much for explaining that, it made good sense to me. Old roper don't worry I have no intentions of "doing anything" to my gun...it shoots great with the right load, it's just choosy is all. Also it's a series 1 vanguard, and I know about the series 2 accuracy guarantee and I do indeed want to upgrade to a series 2 with a stainless barrel and action someday soon.
 
Roadkill2228,

To answer your question, free floating the barrel has little to no impact on point of impact differences between different loads.

If you load every cartridge to the same max chamber pressure, the more massive bullets will have a smaller powder charge and less velocity than the lighter bullets. Bullets with more bearing surface area will also have a smaller powder charge than bullets with a smaller bearing surface area.

The internal ballistics of this says that each load will have a different barrel time, and so be launched at a different point in the recoil cycle and most likely a different point on the muzzle harmonic vibration cycle.

Even then, once the bullets are out of the barrel, the different aerodynamic properties of each bullet will cause a loss of velocity at different rates (although mass doesn't matter at this point because gravity is a constant acceleration regardless of mass).

Since you've found something that shoots well in your rifle, by all means stick with that load. :D

Jimro
 
Will the point of impact changes be less with a free floated barrel or with a non-free floated barrel? There are no other variables to the question.
Click to expand...

With no other variables, the changes should be about the same in either barrel.

The question is not about which type of bedding is "more accurate"

It's just about the change of ONE variable (the load itself), which means its' more about barrel harmonics than anything else
 
You must log in or register to reply here.
Back
Top