Threading and chambering sinaro

[kawsam62s]

Hi
In this sinaro you have a short barrel to thread and chamber, can’t use a spider, it’s to short and no threads on the crown end to make a extension
So use the 3 jaw or over the bed with a steady rest?
Neither one can be indicated in but I have seen a noted gun smith chamber on the steady
Thoughts?
Thx for the comments!!

 

[LVLAaron]

I have some threaded extensions so I can use my flush system... I also have a non-threaded extension that clamps onto the barrel.

 

[gunsandgunsmithing]

Two things...that's a really short NEW BLANK, thus not practical. Two, if it's a previously chambered bbl and you can trust the previous work...the reamer has no choice but to follow the old hole, disregarding anything totally stupid. You'd likely never make it better nor worse than it is with a floating reamer holder and even a 3 jaw. This is just the truth and excludes internet talk. Otherwise, there are a couple of ways but most will put it in a steady. A lot has to do with it being a really short blank or a set back. It's hard to make the reamer follow a different path than the one that's in front of it. We can debate diameters but the difference....hell, in many cases, the prints can be that much different.

 

[AccelR8]

If I understand the question, in other words if it's a barrel that has not yet had the tenon cut and threaded and no chamber, and only a 3-jaw that cannot be dialed in, personally I would put the muzzle on a center in the headstock and cut the tenon and thread it on a center in the tailstock, then chamber with a steady rest.

 

[kawsam62s]

They’re only 20 inches long give or take and their chamber for six PPC I’m gonna change them to six BR. I just ordered a Reamer so the thought occurred to me that I may have to work in the three jaw or do it in a steady rest and there won’t be any way to indicate it in other than use the reamer with a floating reamer head I have to re-thread also, since it’s a six PPC chamber, I have to cut the threads off to get the six BR reamer to Ingauge the pilot into the Rifleing they were for a bat action now going on a stole panda

 

[gunsandgunsmithing]

If I understand the question, in other words if it's a barrel that has not yet had the tenon cut and threaded and no chamber, and only a 3-jaw that cannot be dialed in, personally I would put the muzzle on a center in the headstock and cut the tenon and thread it on a center in the tailstock, then chamber with a steady rest.

Same as I'd do on a set back...if bbl length was a major issue. What else is there, honestly? Then, are you gonna follow lands or grooves. A pilot will always follow the lands. You could put it in a steady and pre bore but are you getting a better result than if the reamer just follows the hole? It introduces more room for error, at the least. At best, figure double the indicated runout unless you're just lucky.

Brings me to borescopes and uneven cuts relative to the lands and grooves. You can have either one but not both unless the bbl is perfect. Pick one. I guess we could ditch reamers and bore to two diameters at the throat but I can envision a lot of messed up bbls in peoples basement shops like that. I've been around tool and die work for a big portion of my life and I don't feel good about that, consistently.

Reamers, almost by definition, follow existing holes very closely by design. They don't make new holes...but are specifically intended and designed to precisely make smaller holes, bigger.

 

[Keith Hansley in NC]

how about a Viper chambering truing fixture

 

[gunsandgunsmithing]

They’re only 20 inches long give or take and their chamber for six PPC I’m gonna change them to six BR. I just ordered a Reamer so the thought occurred to me that I may have to work in the three jaw or do it in a steady rest and there won’t be any way to indicate it in other than use the reamer with a floating reamer head I have to re-thread also, since it’s a six PPC chamber, I have to cut the threads off to get the six BR reamer to Ingauge the pilot into the Rifleing they were for a bat action now going on a stole panda

So, you have no way to indicate and you're looking to improve upon that, that the tool maker didn't, when designing the reamer? Even a poorly made reamer should self center. You could place a range rod in both ends, indicating off of the lands but what's the reamer gonna follow?

 

[kawsam62s]

So, you have no way to indicate and you're looking to improve upon that, that the tool maker didn't, when designing the reamer? Even a poorly made reamer should self center. You could place a range rod in both ends, indicating off of the lands but what's the reamer gonna follow?

On indicating I ment with the 3 jaw it is what it is and the same for the steady rest
Now using the centers and the dog leg will at least machine true to the centers.
And the reamer will not go around a corner,lol it’s always going to follow the pilot

 

[gunsandgunsmithing]

On indicating I ment with the 3 jaw it is what it is and the same for the steady rest
Now using the centers and the dog leg will at least machine true to the centers.
And the reamer will not go around a corner,lol it’s always going to follow the pilot

Yes and no. It'll follow the pilot to about double its clearance on the reamer and to the bore. The reamer follows the hole. The reamer pilot juts binds things up tat aren't aligned with the lands, which is what the pilot tries to follow. Not the same though, when looking for perfection. Think about it.

 

[paperpuncher]

You don’t have to have a threaded muzzle to connect the extension. You could thread if you wanted would likely only cost a 1/2” in length . If length is critical or you don’t want to thread it I have simply bored the extension to slip over the muzzle and used a couple set screws to secure it. Now you can do it with the spiders using methods you normally would

 

[kawsam62s]

You don’t have to have a threaded muzzle to connect the extension. You could thread if you wanted would likely only cost a 1/2” in length . If length is critical or you don’t want to thread it I have simply bored the extension to slip over the muzzle and used a couple set screws to secure it. Now you can do it with the spiders using methods you normally would

And maybe a interference fit tap on tap off
I like the set screws ldea!

Maybe bore a tapered internal hole with the compound to match barrel contor,
I have never tried that!
Very interesting

 

[kawsam62s]

Yes and no. It'll follow the pilot to about double its clearance on the reamer and to the bore. The reamer follows the hole. The reamer pilot juts binds things up tat aren't aligned with the lands, which is what the pilot tries to follow. Not the same though, when looking for perfection. Think about it.

I see said the blind man!

 

[paperpuncher]

And maybe a interference fit tap on tap off
I like the set screws ldea!

A nice slip fit with a couple brass tipped set screws works well for me You can even taper bore to match the barrel if your so inclined

 

[boltfluter]

Cut an extension with matching taper of barrel. Couple of brass set screws. Tap the extension onto the barrel and if your tapers match she is locked in place nicely. Then tighten the set screws just for peace of mind. Not reason why this wouldn't work just fine. Carry on as usual!

Paul

 

[jdh47]

Ed Shilen would tell you to do it between centers. A SB Heavy 10 spindle is 13" long. That's where they shine for short stuff.

 

[Walt Krafft]

You need an Adjust-Tru 3 jaw chuck or a 4 jaw. Chuck it up, indicate it in, and have at it.