Dialing in off the bore with long stem interapid

[slayer_21420]

As the title states I have a question regarding dialing in directly off the bore with long stem interapid.

When installing a muzzle break on a rifle through the headstock, in a 4 jaw with outboard spider, with the receiver still attached to the barrel. Can you effectively dial in the bore by inserting the stem of the indicator into the barrel to where it gimbals on the copper wire, zeroing out the runout, then move the indicator out to the end of the muzzle and repeat until there is no noticeable runout on the dial?

I tried this earlier today and got little or no movement on the dial in both places in the bore, but then i turned the machine on and there was a significant amount of runout on the outboard side that I could see with my naked eye.

Sorry If my wording is difficult to understand

 

[tac284]

When you have the stem of the indicator in the barrel and at the copper wire, which screws are you moving? The outboard spider or the front spider chuck?

 

[slayer_21420]

When inserted to the wire I was moving the chuck jaws

 

[swd]

I think what you getting at is can you end up with it dialed in like you would with a bore rod in 2 separate places to get the last few inches running true? If so, no not with a long stem indicator because the twist will throw your reading off.

With the action on, I just dial in on the outside of the barrel at the spider and off the grove at the muzzle. The spider side is dialed to .001" or less if it's actually round and I dial my muzzle end to a half thou or less on the grove. With the run out on factory barrels it's less than a perfect situation but it works. I generally run my exit at .010" total and rarely have a strike and I've done many hundreds of breaks. If your exits are .020" total you'll never have a problem doing it this way.

 

[slayer_21420]

I think what you getting at is can you end up with it dialed in like you would with a bore rod in 2 separate places to get the last few inches running true? If so, no not with a long stem indicator because the twist will throw your reading off.

With the action on, I just dial in on the outside of the barrel at the spider and off the grove at the muzzle. With the run out on factory barrels it's less than a perfect situation but it works. I generally run my exit at .010" total and rarely have a strike and I've done many hundreds of breaks. If your exits are .020" total you'll never have a problem.

Do you think one would have an issue with this method if the end user was planning to use a suppressor on the rifle in the future?

 

[ridgeway]

When you set up, run your live center in your muzzle and lighly chuck the frontside up. On outboard side, dial on OD of barrel since the receiver is still attached. Go back and dial in your muzzle in one spot close to the crown...1/8" in will work. Goto town cutting your tenon and don't worry about the onboard side.

 

[swd]

It would probably be ok but it would depend on the exit clearance. I'm in a non suppressor state so I have no experience with them, but I would guess the exits are fairly large when compared to a muzzle break. A range rod with the correct bushings would get you there for sure.

 

[slayer_21420]

Thanks for the replies fellas, this is why I love this site.

I'm in Minnesota, about a month ago we became the 39th state to legalize gun mufflers and i'm just getting into this whole machining thing, needless to say all my friends now want threaded barrels :

 

[swd]

Have fun I'm jealous! I'm stuck for at least the next 10 years in a state that will never have them...

 

[jrm850]

It's normal. What you're doing is the correct way to ensure a concentric exit. What you are seeing is just the bend that is present in almost all barrels.

 

[butchlambert]

It's normal. What you're doing is the correct way to ensure a concentric exit. What you are seeing is just the bend that is present in almost all barrels.

Could you explain that please?

 

[Dans40X]

What you are seeing is just the bend that is present in almost all barrels.

Butch,
Must have been a miss-interpreted quote from the internet!

 

[7mmshooter]

It's normal. What you're doing is the correct way to ensure a concentric exit. What you are seeing is just the bend that is present in almost all barrels.

Could you explain that please?

Poor butch. Maybe your should stick with rifle rest and and tension screws. Quit being facetious and and trying to set people up.

 

[181backup]

It's normal. What you're doing is the correct way to ensure a concentric exit. What you are seeing is just the bend that is present in almost all barrels.

This is right on

 

[riflewoman]

Get a fistful of gage pins and indicate off the best fitting one until it is zero. Then use the long stem on the bore. You want to get your thread axis in line with the bore within a thousandth or two. The clearance in the brake or muffler should allow the bullet to pass. You need a fist full because they come in tenths.

 

[escopeta]

I use gauge pins sized +&- example 6mm (.243) bore .236" i use a + or - for best bore fit at the muzzle. Use spiders front and rear unless very short barrel. If particular barrel is out side what I consider a good close slip fit I use the indicator. Thread length for most muzzle devices is 1/2-5/8 of thread. Your bullet bearing surface is less than that. I indicate run-out to within .0005" at muzzle. move the carriage away 1/2 to 1" to insure parallel reading to within .0005" run-out over that distance. Adjust rear spider to get parallel. Have to go back and forth on adjustment to get thins right. Your bullet bearing length will be less than what I said so if you keep thread parallel with that last 1/2" or so you are good for any can or muzzle device.
Have done a lot of specials for South Texas shooters and had to repair a lot of blacksmith jobs.
As for indicator you don't need a really long stem. 3/4-1" is fine for muzzle device. I use my long stem 3" for chamber jobs.

 

[butchlambert]

It's normal. What you're doing is the correct way to ensure a concentric exit. What you are seeing is just the bend that is present in almost all barrels.

Could you explain that please?

Poor butch. Maybe your should stick with rifle rest and and tension screws. Quit being facetious and and trying to set people up.

Could you explain his quote or is it over your head?