Accuracy Tuning With Barrel Bedding?

[Engineering101]

My nephew finished a 338 Edge build recently. It is crazy accurate running the 300 grain Berger at 3040 fps with RL-33 out of a 30 inch Krieger. He mentioned that he used a trick a gunsmith friend of his put him on to which was to bed the action and also a couple inches of the barrel. Then load up some ammo for the velocity you want with the bullet you want and if the bullet holes are not touching at 100 yards take off 1/4 inch of bedding from under the barrel and try again. He struck pay dirt after the 2nd cutback when the group dropped from 1 inch to a clover leaf. He did the same thing with his 260 Rem (also a recent build) and it shoots in the 0.3s.

Since I was bedding my new 26 Nosler anyway, I figured why not give this a try so I put a couple of inches of bedding under the barrel. I have never done this as I was always told you want the barrel to float. However for this rifle, tuning to a particular bullet (127 gr Barnes LRX) makes sense because it will be only for hunting.

Usually you tune the load to what the rifle likes and not the other way around so I'm curious if anybody else out there has used this method to tune a rifle to a particular load?

 

[royinidaho]

Yep, that's a good process.

Plus it's good juju

And good sense as it keeps one from always messing around with various bullets. That is, saves barrel life,

 

[Engineering101]

Roy,

Thanks. Good to know it is a known thing. I wonder why you don't hear much about it as "the way you should do it" like I always heard about floating the barrel?

If this works I may go back to a few other rifles where I could not get a bullet I wanted to use to shoot and redo the bedding the same way.

As for my 26 Nosler, from what I've been hearing keeping the round count down is a very good idea. Although, after 33 rounds down the tube I did just recheck the distance to the lands and it measured exactly the same as when new. I will take that as a positive sign.

 

[royinidaho]

Keeping round count down certainly is an important consideration for a ton of reasons. Not the least of which is barrel live. Stuff is simply hard to come by these days.

What I have found is that a fully custom gun, at least one made by a fully custom rifle smith chambered for a specific bullet leaves little to do to get her shooting. Mostly messing with seating depth.

On one of my DIYs, I started with the barrel fully bedded then started cutting the bedding barrel bedding back until I got what I wanted. Luckily when the barrel was replaced the bedding remained good. Every once in awhile I luck out.

My process is now to start fully floated and tune from there. If I don't get what I want I add bedding an inch or so at a time. So far so good…

33 shots isn't going to show a measurable erosion difference in anything but a very extreme chambering. Some barrels may differ though. The 270 Allen Mag is the toughest on barrels that I have and it takes a lot of shots to begin to see erosion happening. (I just worked up a load with 165 Matrix bullets @ 3500 FPS is an example for fairly extreme performance. The first barrel pushed 169.5 Wildcats @ 3400. That barrel lasted just over 900 rounds. At 900 rounds I did a Tubbs Final Finish process and got original accuracy for 25 more rounds. Then it was over!

 

[EFR]

I have never heard of tuning like this, but by default, did it once myself.

I have a CZ527 in 223 that I could not get to shoot, 1 1/2-2" for three shots at 100 yds from the factory. I pillar and glass bedded it at the same time. Brought accuracy down to 1-1 1/2". Still wasn't happy. I noticed the bedding compound squeezed out under the chamber and down into the barrel channel a little more than I usually do. Trimmed up about 1/2" and squared it up with dremel. That little bit brought that rifle right into 0.5-0.75" capability.

That was by accident, but I'm not arguing with the results.

 

[Engineering101]

Sounds like this process is not exactly mainstream which is probably why you don't hear it mentioned much - most people don't know about it (or have done it by accident as EFR said). I have been messing with guns/reloading since the 1950s and I always thought you should do the opposite and float the barrel. I find it interesting that Roy who does know about this trick starts with the barrel floated and adds bedding if needed (hadn't thought of that one).

Good to hear that you can get 900 round out of what should be and extreme barrel burner - 165 grains at 3,500 fps is smokin'. I've figured with the 26 Nosler I'll need only 16 MOA dial up to get to 1,000 yards which is not even 1 revolution on the VX6 turret. Just curious but what is your 1,000 yard dial up for your 270 AM?

 

[Engineering101]

Well the rifle is all set and preferred ammo is loaded. I'll be finding out tomorrow morning if this works or not. I'll post the targets as the cut backs occur which I'll be doing at the range all in one go. If I have to cut all the bedding out I'll just end up where I would have started in the first place - with a barrel that floats. Should be interesting.

 

[HARPERC]

It's about barrel harmonics, some adjust loads, some use "Boss" type devices, and others use the bedding.

Look at some of the high speed film of barrel whip especially with muzzle breaks (JE Custom has posted some here) and ask yourself is a dollar bill's worth of clearance going to eliminate contact.

I've used strips of tape at the for end, add a strip and shoot. I've seen rifles get better as the tape builds up then there is a point accuracy declines.

About a month ago a friend with a Model 70 Classic in .338 Winchester that never shot better than just under 3 inches at 100 yards, laughed when I dug a target out of the garbage, folded it, and stuffed it under the barrel, first group 1 inch.

I reminded him of an .338 Edge I bedded in the same way. He hunted 2 seasons with folded target under the for end.

I've seen it work a bunch of times. If free floated shoots don't mess with it. The lighter weight barrels in magnum chambering's tend to show greater benefit.

 

[Engineering101]

Harperc

All about barrel harmonics you say. Good info thanks. I'm headed to the range in a few minutes to get some first hand experience on all this. The rifle shot .75 MOA with no bedding and I'm hoping to get it down to 0.5 MOA with the lug and barrel nicely supported. I'll post some targets when I get back.

 

[Engineering101]

Ran into a problem - a warm day. Started getting sticky bolt and 3,500 fps where previously I was seeing 3,450 fps. Also, I didn't like the ES I was seeing so I decided to switch from Magnum to RL-33. I picked a load that should have been slower but it wasn't. It was still pushing 3,500 fps with RL-33. Interestingly the primers were clearly less flat with RL-33 and no sticky bolt at 3,500 fps. But... I'm still going to slow it down. I've got the slower stuff loaded for another try on Thursday. The nice thing about tuning the rifle to the load is once I get the velocity I'm looking for I'm done messing with the load and can start messing with the rifle.

 

[HARPERC]

Ran into a problem - a warm day.

...and that was on the temperate side of the state.

 

[royinidaho]

Good to hear that you can get 900 round out of what should be and extreme barrel burner - 165 grains at 3,500 fps is smokin'. I've figured with the 26 Nosler I'll need only 16 MOA dial up to get to 1,000 yards which is not even 1 revolution on the VX6 turret. Just curious but what is your 1,000 yard dial up for your 270 AM?

MOA @ 1000 hangs right around 17 MOA at various shooting locations, atmospherics and other stuff with the 169 Wildcat.

Shooter says the Matrix may be at least 2 MOA less. We'll see.

This is with a 100 yd zero.

Velocity is sweet. I get a rush out of the short time between bang and dust out there a long ways.

 

[Engineering101]

Turns out my bedding experiment was a bust. The rifle shot horrible and the round count kept going up which if there is any rifle you DON'T want to do that with it is this one. So, I decided to just float the barrel and get on with it while I've still got some barrel life.

I actually shot this rifle before I had the smith rebarrel to 26 Nosler. It shot 1.5 inches at 200 yards as a 7mm Rem Mag with some scrap components I just threw together. The idea was to work any issues out of the setup before the new barrel went on. Since then I've had the new barrel installed (Kreiger bull sporter) and I bedded the recoil lug. Since it shot decent before and has a pillar in the back, I didn't bother bedding the whole action. This adventure did lead me to switch from Magnum to RL-33 and the ES is pretty good now. On Monday I'll find out if floating the barrel made it better. If it will do 0.75 MOA as a 26 Nosler, I'll load up some ammo and get ready for bear season which is coming up pretty darn fast.