Bedding an action

[Buckshot85]

What determines when or why a rifle would be fully beddded?
My Barrett Fieldcraft is fully bedded and is very accurate.
My custom built rifle is action bed only and shoots good but recently went to crap. Been chasing that demon.

 

[Tumbleweed]

When you say fully bedded, do you mean action and full length of barrel channel in contact with the barrel?


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[Buckshot85]

Yes

 

[Tumbleweed]

I'm not sure why anyone would want the full length of barrel bedded. You want the barrel free floated so that it can vibrate, but vibrate consistently. I would have to think that a full bed job would create poi shift as the barrel warmed up.


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[gelton]

Yeah, I agree with Tumbleweed, never heard of anyone bedding the barrel. How many rounds through the custom and what scope?

 

[Wrench]

I've had success FL bedding rem mtn contour barrels into solid stocks.

 

[False_Cast]

Full length bedding, done correctly with a properly stress-relieved barrel (read: Barrett and Barrett), is remarkably consistent (which is exactly why you bed).

Re: your “custom” ... what optic? I’d check, and double check, fasteners & assembly first, assuming you’ve an optic of repute.

 

[Buckshot85]

Barrett does it in the Fieldcraft successfully. No POI shift.

 

[Buckshot85]

Guess Ive never been in a situation where a hunting rifle got heated up either.

 

[Tumbleweed]

Guess Ive never been in a situation where a hunting rifle got heated up either.

We hope not, right? Lol


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[Wrench]

a rem mtn contour is warm in a couple of shots and flat hot in 5.

 

[Buckshot85]

I only shoot 3 shot groups, not 5.
You’re hunting rifle should be cold barrel zeroed.
Of course you can heat it up, but why?
Makes no sense.

 

[Kimber7man]

Melvin Forbes does it with his New Ultra Lite Arms (NULA) rifles. Can fire 10 shots without it walking. I think he pretty much has it perfected. IIRC Barrett bought the remaining rifles and design from the Forbes rifles (an attempt at factory producing rifles with the model 24 action that Melvin designed).

 

[Tumbleweed]

I only shoot 3 shot groups, not 5.
You’re hunting rifle should be cold barrel zeroed.
Of course you can heat it up, but why?
Makes no sense.

I don't think anyone plans to heat them up in hunting situations. But if things go sideways for whatever reason and the animal is still standing. Keep shooting


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[Dhbwa]

Full length bedding, done correctly with a properly stress-relieved barrel (read: Barrett and Barrett), is remarkably consistent (which is exactly why you bed).

Re: your “custom” ... what optic? I’d check, and double check, fasteners & assembly first, assuming you’ve an optic of repute.

what he said.....

 

[Tmac]

I've had success FL bedding rem mtn contour barrels into solid stocks.

Ditto.

 

[wyo2track]

I recently went through an exercise with a Ruger M77 in 7x57 which has a long throat. I took it out of the original wood stock which had no bedding but a slight point of up pressure near the forend at the bottom of the barrel. I put it on a new stock, bedded the angled recoil lug and tang and free floated the barrel. I had quite the trouble getting the gun to shoot decent groups with cup/core/bonded bullets. Best about 1 1/8" groups and I played with the seating depth as much as I could and determine it liked longer bullets. Switched to Barnes TTSX and they shot 3/4". Well ok, but be nice to have just a inexpensive bullet for practicing. I went through the rounds (literally) with different powders and bullets. I finally succumbed after a group and pushed a little wedge into the forend and taped it good so it wouldn't move. I measured the lift and it was 0.020" from the free floated position at the forend. Incredibly, my 140 bullets went from a 2 1/2" 3 shot group to a 1/2" 3 shot group with 0.020" of upressure. Changed the entire barrel dynamics, but I also wonder if it help pivot the angle recoil lug downward into the stock. I ended up bedding just a dime sized pad of devcon at the forend that adds 0.015" of barrel lift and its shooting great now. So, don't think a barrel has to be free floated to achieve accuracy, this particular barrel and rifle loves having some pressure at the forend. My 2 cents.

 

[TAArrowood]

In my experience full or partial action bedding helps most rifles shoot better.. Bedding under the chambered portion can make a difference in some rifles... To bed the full barrel length shouldn't (in theory) add any vale to accuracy... Again, in my experience if the barrel is free floated it should minimize the effect heat has on metal as well as issues with stock contact. If the barrel does, in fact, warp (causing the impact point to "walk") it is generally an indication that the metal has stress in it and the heat is allowing the metal to move in the direction of the stress.. Technically most metals have stress induced by the manufacturing process, but it generally doesn't matter as much as it does in barrel making.. Also, stress can be introduced by the machining process... Most of the better shooting barrels are cyrogenically "frozen" (sometimes multiple times to well below zero) to relieve stress and align the "grain" of the metal. If this is done before machining has started the metal machines better and much less stress in induced.. Sometimes the metal is put through a tempering process to normalize the metal structure. If most of the stress has been removed/relieved before machining it lessons the amount that is introduced during machining. All this extra care in preping the barrel blank is the reason only a few barrel makers can claim to make great barrels repetitively and the reason they get a premium for them.. Great barrel making is an art.. A so-so barrel can usually be made to shoot better through bedding, etc for hunting accuracy, but you shouldn't think that you're going to pickup any off the rack rifle (By any maker) and get tiny groups consistently, especially as temps and other conditions change.. Just my 2 cents, but I've built a bunch of rifles the shot well and a bunch that didn't..

 

[Wapiti1]

To answer the original question, barrel contour and length dictates if full length bedding, or even pressure bedding is to be considered. Thin barrels, and especially thin long barrels often shoot better bedded than floated. By thin, think #2 or lighter contours and over 20" long. This isn't always the case, but I've seen generally better results bedding light barrels than floating them.

The reason is a couple of things. Bores are not straight making the wall thickness along the length inconsistent. On a thick barrel, this doesn't result in as much whipping around due to geometric stiffness. Thin barrels are less stiff, and move more. Combine inconsistent wall thickness with more movement and you have a much reduced accuracy node. Things have to be in a very tight band to get the barrel to be in the same spot every time a bullet leaves it.

Bedding shortens the effected barrel length by adding stiffness and reduces the magnitude of the barrel movement. Pressure bedding acts as a shock absorber to the barrel movement damping it.

Its simple physics. It's easy to bend thin things and hard to bend thick things. Accuracy is about getting the barrel in the same exact position every time the bullet exits. Stiff barrels do that much easier than thin ones. Go on youtube and watch some slow mo video of rifle barrels being fired. They move a lot.

Jeremy