Burned Out Barrel
- Thread starter alberta tactical rifle
- Start date
Very neat, too bad we don't have a new factory barrel to cut in half for a bit more of a apple to apple comparison.
However, I think it still illustrates the value of a match aftermarket barrel.
I better start shooting more to burn out my current factory one.
However, I think it still illustrates the value of a match aftermarket barrel.
I better start shooting more to burn out my current factory one.
Here we see a closeup of the same chamber as above (top) compared to a custom, hand polished match chamber (bottom) cut with a new, sharp reamer. The chamber walls are bright and shiny with no tooling marks and the transitions from body to shoulder and shoulder to neck are sharp, not rounded.
Just wondering if we're comparing apples to apples. Are they both .308's? Top looks like an everyday standard .308 factory chamber. The bottom one looks like a completely different chambering, appears to be less body taper, a longer body, steeper shoulder angle and a longer neck almost looks like a .308 AI or something. Regardless it's a nice example of reaming.
- Location
- calgary alberta
YOU go to the head of the class!!
They are different calibers. The top 1 being 308.
The lower photo is of a 260AI chamber that I was not happy with so scrapped the barrel and started anew. Some would have let it go, but I am ultra fussy about my chambers. You can't see it but there is .002 run out in the 260AI chamber and if you look real close just ahead of the shoulder there is a slight ring, which to me is also unacceptable.
Basically the photos were to illustrate what is acceptable as a factory chambering and how the throat is eroded, compared to what a chamber should look like with no throat erosion.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Playing the Devils advocate:
Throat looks like it is just right for the heavy VLD's
Chamber may look bad but was more then good enough to digest alot of rounds thus leading to the worn bore. The discoloration is very common to any CM steel that has seen weather as I am sure this working rifle has. Likely some of it is just remnants of the orig bluing.
Most 308 chambers ARE sloping especially in the neck/shoulder junction. The bend for the body/neck junction looks fine. That extra clearance is very beneficial in a working gun. Makes for easy extraction when heavily fouled.
Look at reamers used for other working rifles and you will see similar tapers. If you ever do a chamber cast of an SKS and likely an AK, you will understand what I mean.
Many competition chambers have throats that look as long as this one. When my 6.5 barrels are burnt out, there is little rifling for further distance in front of the chamber.
I bet if my barrels were sectioned, they would look like crap but they still shot around 1/2 to 3/4 min when I pulled them. Not enough to hold the X ring. When these barrels were cut and set back, they would look just fine too.
Nice reaming. What is the chamber? Improved something or other???? Most of the chambers I have received were not that highly polished for fear of increasing bolt thrust but it does prove a point.
Barrels by nature, don't look pretty after they have seen a bit of use. However, the tiny groups they can deliver is what interests me.
Pity, the rifle couldn't be used with handloads...If the actual bore of this barrel was not greatly reduced, a change in bullet might have lead to acceptable performance.
Jerry
Throat looks like it is just right for the heavy VLD's
Chamber may look bad but was more then good enough to digest alot of rounds thus leading to the worn bore. The discoloration is very common to any CM steel that has seen weather as I am sure this working rifle has. Likely some of it is just remnants of the orig bluing.
Most 308 chambers ARE sloping especially in the neck/shoulder junction. The bend for the body/neck junction looks fine. That extra clearance is very beneficial in a working gun. Makes for easy extraction when heavily fouled.
Look at reamers used for other working rifles and you will see similar tapers. If you ever do a chamber cast of an SKS and likely an AK, you will understand what I mean.
Many competition chambers have throats that look as long as this one. When my 6.5 barrels are burnt out, there is little rifling for further distance in front of the chamber.
I bet if my barrels were sectioned, they would look like crap but they still shot around 1/2 to 3/4 min when I pulled them. Not enough to hold the X ring. When these barrels were cut and set back, they would look just fine too.
Nice reaming. What is the chamber? Improved something or other???? Most of the chambers I have received were not that highly polished for fear of increasing bolt thrust but it does prove a point.
Barrels by nature, don't look pretty after they have seen a bit of use. However, the tiny groups they can deliver is what interests me.
Pity, the rifle couldn't be used with handloads...If the actual bore of this barrel was not greatly reduced, a change in bullet might have lead to acceptable performance.
Jerry
Heres a question for the gunsmiths...
If you had a straight barrel with NO taper, could you just cut and ream a new chamber further up where the throat is not eroded?
Would it be worth it?
Nice pics, I love cross-sections, they help alot.
If you had a straight barrel with NO taper, could you just cut and ream a new chamber further up where the throat is not eroded?
Would it be worth it?
Nice pics, I love cross-sections, they help alot.
On the rounded transitions. Just took a look around the web and pretty much confirmed what I thought. The transitions noted as being rounded, are supposed to be rounded. Case to shoulder, aprox .03 radius, shoulder to neck aprox .125 radius.
Those probably are well within tolerances.
How did it shoot before it was cut up?
Cheers
Trev
Those probably are well within tolerances.
How did it shoot before it was cut up?
Cheers
Trev
- Location
- calgary alberta
1/4 minute of large house accuracy
- Location
- calgary alberta
The chamber should not change much assuming it is kept clean.
You do not get tool marks from shooting
That little ring, that's nothin, if your going to get a ring that's the place to get it rather than the body or neck. The 2 thou runout would concern me on a bench gun but not so much on a hunting rifle. If only the factories could keep chamber runout remotely close to 2 thou and lined up somewhat close to the center of the bore so the lands all start at the same place, life would be good!
- Location
- calgary alberta
A very highly polished as in mirror finish will certainly increase bolt thrust as the casing does not "stick" to the chamber.
However brass casings DO stick to rough chambers making extraction difficult and case life is also shortened.
Getting the happy medium is the trick
hah, cool. thanks for sharing
This is done all the time (called "setting back") and one does not need a straight blank, just enough straight metal at the shank end to allow the set-back. The back of the barrel is cut off and you start over. New threads need to be cut as well as the new chamber. Typically a chamber is rough reamed or drilled first and then finish reamed to save wear on the reamer.
This is often a very economical way to go and the resulting barrel, although shorter, can only gain accuracy.
Good thing I read Obtunded's post before throwing in mine.
Anyway, I had a conversation with a serious shooter a while back, and he said much the same thing.
In fact, he felt that after re-chambering, the barrel actually shot better than new, as any microscopic burrs left in the barrel from the original rifling process had been smoothed away at this point.
Anyway, I had a conversation with a serious shooter a while back, and he said much the same thing.
In fact, he felt that after re-chambering, the barrel actually shot better than new, as any microscopic burrs left in the barrel from the original rifling process had been smoothed away at this point.
- Location
- Ft. Mac. Alberta
Most gunsmith/competitors I know say different, Bill Shehane, for one.Good thing I read Obtunded's post before throwing in mine.
Anyway, I had a conversation with a serious shooter a while back, and he said much the same thing.
In fact, he felt that after re-chambering, the barrel actually shot better than new, as any microscopic burrs left in the barrel from the original rifling process had been smoothed away at this point.
I do know that My 6.5WSM di nor shoot as well after cutting back 4" of wash and rechambering, and two of my Palma rifles also di not shoot as well.
These were all rechambered by top 'smiths.
Cat
