Gunsmithing Anybody cut the chamber down and re-chamber & Thread to get more barrel life?

[Sticks]

If I am understanding this correctly, the barrel life usually dies at the throat and beginning of the lands.

If one had a heavy profile barrel that would allow cutting off an inch or two and re-thread and chamber increase the usable life of the barrel?

I have heard of people buying "shot out" barrels, and cutting them down for a smaller chambering in the same caliber - I.E. taking a 6.5 SAUM or CM and cutting down for a BR or Grendel.

 

[cwinner]

Works great....I've done it many times both going back with the original chambering and or making AR barrels as you suggest. One of my favorite uses for old match barrels is to throw them in the lathe and turn pencil weight profiles on them and fit em up to make hunting rifles.

This said, I do all my own work so my time is free and therapeutic for me.......i doubt it makes sense from a resale/business perspective.... the cost of a premium cut blank is insignificant in the cost of a new build.

 

[gnochi]

You can do that, but cutting and rechambering doesn’t cost that much less than buying a blank and chambering. Depending on the gunsmith, it may well cost more.

 

[tsu45]

Commonly called a barrel “setback” I believe.

 

[Terry Cross]

Throats don't just erode for X amount of distance and just stop while instantly transitioning to a pristine bore surface.

The damage is tiered in that the most severe is immediately in front of the lead and then it s l o w l y decreases in severity as you move away from the chamber/lead.

Barrel bores are like new highways. Everything is hunky dunky and no surface damage until the first cracks start appearing. Then everything goes to shit rapidly.

Setting back a barrel is never going to give you the same extended barrel life as that blank did when it was first chambered because you are still starting with a damaged bore surface immediately in front of the new chamber unless you cut off several inches of the breech end.

Exceptions are when a barrel is not really "shot out" and the lead is still relatively intact. We have seen a ton of barrels that were "shot out" except they really weren't........... Go figure.

Even if they shot great afterward, I refuse to do it because of the difficulty of indicating a truly damaged bore in the machine. Even the live reamer pilots will have to be changed as you proceed deeper into the barrel.

My 2 cents is that if the barrel throat/lead is truly toast, get a new blank and rock on. Life is short. You will enjoy more fine accuracy, less drama and less wasted ammo/time.


./

 

[shoot4fun]

I had a barrel that had about 1000 rounds of 6 Dasher thru it. The throat was eroded and there was some fire-cracking ahead of that. I decided to run my 6 Creedmoor reamer in, saving the original tenon, and give it a go. Bad idea. Even though the Creedmoor reamer appeared to clean the Dasher chamber well the pressure went thru the roof once the 6CM was tried in it. So bad that backing up two grains did nothing to help. Close inspection revealed issues in the new throat so we wound up cutting the chamber off and doing the job again. While pressure issues were resolved the barrel was never as accurate as before.
Now, on the other hand, I did get a 6BR barrel rechambered and the results have been impressive. It was a great shooting barrel but once the throat got too long to chase I decided to get it redone. Tenon was cut off, still leaving the barrel right at 27 1/2" and a fresh short free-bore chamber was cut. That barrel is on a long-range BR gun and won a bunch of matches this year. In fact, I may cut it back one more time before I let it go.

 

[missed]

I used to set back barrels. Like Terry started, many inconsistencies. I have had some I have set back not shoot anywhere near the original. I have had some shoot good for a 100-200 rounds and turn to crap rapidly. Now I just shoot them till they don't and spin the new one on.

 

[TACC]

Never heard of this process before.
Great info and knowledge here thanks

 

[Deleted member 113831]

Throats don't just erode for X amount of distance and just stop while instantly transitioning to a pristine bore surface.

The damage is tiered in that the most severe is immediately in front of the lead and then it s l o w l y decreases in severity as you move away from the chamber/lead.

Barrel bores are like new highways. Everything is hunky dunky and no surface damage until the first cracks start appearing. Then everything goes to shit rapidly.

Setting back a barrel is never going to give you the same extended barrel life as that blank did when it was first chambered because you are still starting with a damaged bore surface immediately in front of the new chamber unless you cut off several inches of the breech end.

Exceptions are when a barrel is not really "shot out" and the lead is still relatively intact. We have seen a ton of barrels that were "shot out" except they really weren't........... Go figure.

Even if they shot great afterward, I refuse to do it because of the difficulty of indicating a truly damaged bore in the machine. Even the live reamer pilots will have to be changed as you proceed deeper into the barrel.

My 2 cents is that if the barrel throat/lead is truly toast, get a new blank and rock on. Life is short. You will enjoy more fine accuracy, less drama and less wasted ammo/time.


./

I have a 338AllenXpress barrel that is a 36" 1.35 diameter straight tube, and it is about done. I was going to cut 6" off the chamber end rechamber.

Do you think it would be worth doing in this case?

 

[Forward543]

I think Terry is right in the setback. If you do it, you need to go pretty far. A bore scope will tell you how far is fire cracked, and if this is a match gun, hedging your bets with a new barrel is cheaper that a rifle that does not shoot well with extra work on top.
But to cut 2-4" off of a barrel that is not destroyed can get you another 1000 rounds. Really depends on your requirements and what is the goal.

 

[Terry Cross]

I have a 338AllenXpress barrel that is a 36" 1.35 diameter straight tube, and it is about done. I was going to cut 6" off the chamber end rechamber.

Do you think it would be worth doing in this case?

That is like asking somebody on the internet how much cereal is in your pantry.
Looking is the only way to give a reasonable answer (honestly, a guess).

If the round count/damage is low then you may get by with less than 6" removal. If severe, you may still be in rough territory.

Again, I am not a very good authority on this because I stopped setting barrels back over 20yrs ago. Somebody that currently does a lot of this should chime in.


I have seen a couple of 6mm Rem barrels and a 220 Swift barrel with the rifling gone approx 4 inches in front of the chamber with another 4 inches of damage trailing off in front of that. All 3 barrels were still sub MOA but had gotten slow as shit. NOTE: I did not attempt to set back any of these. Just sharing for related info.

./

 

[DAVETOOLEY]

Like Terry I stopped doing this decades ago. The heat checking however holds carbon. It's hell on reamers. You may get 40-50% more life out of the barrel. With the cost of components to retune just not worth it.

 

[Bradu]

The only way I could see setting a barrel back is if you chambered your own barrels. Spending $250+ to setback and rechamber doesn't make sense to me but that is my opinion.

 

[MakeSawdust]

I just got a cheap teslong bore scope for Christmas. I stuck it down two burnt up 243AI match barrels. I ran 105-115 gr bullets with H1000 exclusively. The first barrel shot .25-.4 for 2200 rds and then opened up to .6-.8. at 2700 rds it would no longer hold vertical and the groups went off the reservation. The second barrel went 2400 rds shooting in the .4-.5 range. The velocity was still good but groups went to shit. When I stuck the bore scope down them for giggles, both had rifling gone for a few inches in front of the chamber. There was very little fire cracking, but what was there extended about half way down the barrel.

It blew my mind that they shot so well right up to the end with that much of a mess in there. I'm looking forward to watching the progress of wearing a few out in the coming seasons.

After looking at that carnage and comparing two newly chambered barrels, I can't imagine dumping more money into a barrel that doesn't shoot to rechamber it.

In my experience, a lot of the barrels accuracy comes from the quality of the chamber job. As the two accomplished gunsmiths both mentioned, getting a trashed throat set up in the lathe again would be pretty sketchy. I can think of a couple ways that might work, but I sure wouldn't want to stake my reputation on it if I were a gunsmith. If I am going to spend $250 on a chamber job, I want it to shoot as well as it can for as long as it can.

If you do your own work, it may be worth it to set it back every xxx rounds depending on caliber in order to get the most life and accuracy out of the barrel. Based on people that do this and have it work well, it is usually done while the barrel is still shooting well. Setting back a shot out barrel appears like it would likely be a large waste of time and money.

It seems to be a topic with a lot of variables and mixed results. The fact that Dave and Terry refuse to do it is pretty telling though.

 

[Nodakplowboy]

I had it done once to a 22-250 that had seen hard use P-dogging. Accuracy did not return like I expected and the barrel went completely south in 200 rounds. It was not worth the effort or expense.

 

[Maxduty]

The amount of experience I have in this is a .243 that was set up to shoot ground hogs back east. 55 grain bullets at max velocities wore that barrel pumb out in a summer. Had it cut back 2" and re-chambered thinking it would help, but I never got my accuracy back. It shot for another 1500 and opened up to a group that I could have bested with throwing rocks. For the price of a new barrel, it was a no brainer to just replace it.