Xbolt barrel cut and crown?

[yotaholik]

I am in north ga and looking for recommendations for a good smith who can cut and crown a browning xbolt (eclipse target 6.5 with 28 inch heavy barrel). I want to go down to 18 inches but doesn’t have to be exactly 18, 18-20 would be ok if that’s where the barrel needs cut for accuracy? Can a smith check the bore and know the best length cut for accuracy as far as loose area in bore etc.? I’d appreciate recommendations for a good smith near me if possible. Thanks folks

 

[ReservoirDawg10]

I don't really understand what all you are asking with "loose area in the bore." Assuming you are referring to free bore. Factory barrel/chambers tend to be cut long to prevent potential pressure issues. You'll need to have the barrel pulled, shank set back and re-cut the chamber if you want it tightened up. I'd suggest just rolling your own ammo if you are trying to squeeze every bit of accuracy out of the rifle and don't worry about the chamber.

As far as barrel length, it is not going to affect accuracy, but you will lose velocity. Have the barrel cut to your desired length and then, once again, load your own ammo specific to your rifle.

I'd go to APA, American Precision Arms. Jered is one of the best in the biz and he can explain anything you want to know.

 

[Braxton1]

I respectfully partially disagree with the statement that barrel length is "not going to affect accuracy". While this is absolutely true if one tried to say "A 22-inch barrel is always going to be more-accurate than a 16-incher...", there is another issue that can come up, either as a positive or negative: Harmonics.

The harmonics in a barrel can be rather unpredictable, as barrel thickness, profile, and length (along with projectile velocities) all affect it. The OP could cut the barrel to 17.3 inches and that be the absolute sweet spot with a sudden spike in accuracy, but conversely, 19 inches could ruin it. The sad thing is that you never really know what that magic number will be.

I fully agree with the statement about chambering. Handloading for this barrel would give more bang for the buck than just about any machining operation would.

I have cut-and-crowned a few 6.5 and 6 Creedmoors, but the overarching reason was portability. Hunters didn't like dragging 26 to 28 inches around in the woods.

 

[GAgunLAWbooklet]

Barrel length affects accuracy in this way:

due to barrel harmonics (barrel whip or barrel flex, caused by the bullet muscling its way through the bore, while spinning at the same time), there will be more flexing observed in a long barrel than a short one.

There will be more flexing in a skinny barrel that a thick one.

Therefore the most accurate barrel --strictly speaking of group size --will be short but very thick.

You "can" get good groups from a barrel that has more flex but you have to really fine-tune your hand loads to match the barrel whip, so that the bullet always leaves the barrel while it is at its maximum deflection to one side (temporarily paused before flexing back in the opposite direction.)

 

[ReservoirDawg10]

Both of you are missing it. I get your argument, but you are not inherently changing the accuracy potential of the rifle by chopping the barrel or going longer. Yes, you may hit a node differently, but that is true of all barrels and all ammo. And it can change from lot to lot of any given ammo. It's a crap shoot. If you want the utmost accuracy, roll your own ammo specific to your rifle. No way around it. Making the barrel shorter is not going to increase accuracy. It may make it easier to find a node, but that is it.

 

[yotaholik]

I do load my own ammo for each rifle. The main reason for cutting length would be for portability as an every once in a while rifle as 28 inch barrel is pretty long for mostly woods work. I guess I worded it wrong about “loose area in bore” but in all honesty I only know a few things I’ve read saying if cut at say a slightly “rough” area in the bore and that area was at the crown it may not be as accurate. Anyway I don’t know this to be true was just a question I wondered about.

 

[yotaholik]

It is a heavy barrel and figured would shave at least a pound of weight and maybe balance a little better if cutting off around 9 inches of steel

 

[cmshoot]

We can cut, crown, and thread it at TruPrep in Marietta.

 

[ReservoirDawg10]

I do load my own ammo for each rifle. The main reason for cutting length would be for portability as an every once in a while rifle as 28 inch barrel is pretty long for mostly woods work. I guess I worded it wrong about “loose area in bore” but in all honesty I only know a few things I’ve read saying if cut at say a slightly “rough” area in the bore and that area was at the crown it may not be as accurate. Anyway I don’t know this to be true was just a question I wondered about.

A good smith won't mess it up. It isn't rocket science, but care and time needs to be taken in the set up and then sharp tooling.

 

[Trentonhooper]

Barrel length affects accuracy in this way:

due to barrel harmonics (barrel whip or barrel flex, caused by the bullet muscling its way through the bore, while spinning at the same time), there will be more flexing observed in a long barrel than a short one.

There will be more flexing in a skinny barrel that a thick one.

Therefore the most accurate barrel --strictly speaking of group size --will be short but very thick.

You "can" get good groups from a barrel that has more flex but you have to really fine-tune your hand loads to match the barrel whip, so that the bullet always leaves the barrel while it is at its maximum deflection to one side (temporarily paused before flexing back in the opposite direction.)

Thankyou for the thread fellas as I am learning a lot, I appreciate the information