What's new
What's new

What sis for barrel plug/center?

blkcloud

Plastic
Joined
Jan 2, 2007
Location
pulaski tn
I'm threading a .308 for a silencer, Im wanting to Thread it between centers I'm going to turn a brass plug with a center in it about 1 1/2 inches long and .305 . 306 .307 in diameter... so I can be sure the outside is running true to the inside.. That's what I'm wondering.. what diameter will be a snug fit . I did a test one today that was .3081 in diameter and it wouldn't think of going in..
 
You can make a both ends with a center plug and step it in three .001 steps from go to no go and it will lock up where it needs to and run straight.
You can blue up a 308 bullet and micrometer where it fits.
 
I would expect your plug diameter needs to be .299 to .301 depending on the rifling type if .308 is your groove diameter.
 
FredC is right..

For example, the bore diameter is .300 inch for a typical .30 caliber cartridge like the .30-30, .308 Winchester, .30-06 or .300 Magnum. The rifling grooves are then cut into the bore. The distance across the grooves is called the "groove diameter." This varies depending on the caliber, but measures .308 inch for typical .30 caliber cartridges.
 
I threaded a .308 barrel a few days ago, I turned down a bore pin to .300". The .308 come in three bore sizes .298,.299,and .300

You can make a both ends with a center plug and step it in three .001 steps from go to no go and it will lock up where it needs to and run straight.
You can blue up a 308 bullet and micrometer where it fits.
 
So you are saying that a suppressor has less than .001" clearance for the bullet?

They vary by model, caliber, and manufacturer.

Additionally, like most things in barrel work, it's less about diametrical tolerance and clearance, and more about the effects of misalignment several inches down bore.
 
With having no way to measure one might put a 3/8 wood dowel in any chuck .. Turn it down to .304 inch.. then shave cut it by a few tenths till it starts a little.. then hand wrench it into the bore so it marks the wood well.
With that to measure you will know the size perhaps +- .001 and so save a little time sneaking up on the bore size.

silencer ID to bore size is some gauge to your tolerance. You don't want it to look bad with being very far off. I am thinking that .003 error would be the maximum and .0005 or .0015 the target.

Think the clearance may be .020 to .050 but I am not sure.

* Barrel center plug should be made held between centers, not held in a chuck or collect.

* A 4jaw held part indicated to dead zero might be .003 off inside the jaws.

* Collects are much better than a chuck but very often are .0005 or more off.

* Between center one can take it from the lathe and try it .. then put it back and take a shave.

* Yes any chuck turning the plug (or collect) with a tool bit started center, make size then part off will be right on (very close). (toss the piece held in the chuck or collect).
 
[Quote Originally Posted by tdmidget View Post
So you are saying that a suppressor has less than .001" clearance for the bullet?]

Not me... I said .020 to .050 from old making them before they were legal and much guessing on the size..and I added I'm not sure.
 
LOL , I'm not worried about "precision rifle work" from someone who doesn't know groove diameter from bore diameter. In any case this is all barking up the wrong tree. Take a piece of brass or aluminum, face the end, center drill it, put the tailstock center in it, and about 1/2 inch closer to the chuck cut a 60 degree taper down to about .200. part off and put between the muzzle and center. Voila! no damage to the muzzle, no quibbling about clearance and done in the time it takes to read this.
 
LOL , I'm not worried about "precision rifle work" from someone who doesn't know groove diameter from bore diameter. In any case this is all barking up the wrong tree. Take a piece of brass or aluminum, face the end, center drill it, put the tailstock center in it, and about 1/2 inch closer to the chuck cut a 60 degree taper down to about .200. part off and put between the muzzle and center. Voila! no damage to the muzzle, no quibbling about clearance and done in the time it takes to read this.

I was thinking about this as well, not being a gunsmith I was unsure as to what issues it would cause versus making one that properly fits the bore, so why would this system not be used more commonly?
 
Can't believe that anyone would pay 30 bucks for that. I need to start making and selling such trinkets to the "gunsmiths" and get rich.

$30 for 10 of the smaller caliber ones (Up to .45)
$20 for 3 of the larger ones (.50)

so $3 each, if you could make and sell them for that while turning a profit, start up the lathe!

EDIT: This wasn't sarcastic :D
 








 
Back
Top