texashuntingforum.com logo
Main Menu
Advertisement
Affiliates
Advertisement
Newest Members
Misson1, DJM139, Crazy good, Rosales land management, GrendelHunter73
71995 Registered Users
Top Posters(All Time)
dogcatcher 110,788
bill oxner 91,416
SnakeWrangler 65,418
stxranchman 60,296
Gravytrain 46,950
RKHarm24 44,585
rifleman 44,461
Stub 43,771
Forum Statistics
Forums46
Topics537,052
Posts9,719,906
Members86,995
Most Online25,604
Feb 12th, 2024
Print Thread
Barrel Threading Concentricity Tolerance ???? #5813803 07/01/15 10:53 PM
Joined: Apr 2010
Posts: 1,228
D
dredd Offline OP
Pro Tracker
OP Offline
Pro Tracker
D
Joined: Apr 2010
Posts: 1,228
I have a Suppressor coming in within the next month (I Hope).
I am going to need two Barrels threaded. ( 5/8-24 )

I stopped by Alamo Precision today to discuss it.
First time I have been there.

The gentleman at the counter said that he can hold "Ten Thousandths on Center". ( 0.010 )

I am not a Gun, Barrel or Suppressor Manufacturer, but that sounds "loose" to me.
Granted, that is 0.005 per side, but that still seems like quite a bit coming from a custom shop.
I repeat... I do not thread Barrels, so I do not know.

I did try to Google it, but didn't really find what I was after. (Probably poor searching skills)

Does anybody have any "hard" numbers that one should expect their Barrel/Thread Concentricity to be held to?

Thanks!




Barrel Threading Concentricity Tolerance

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5813805 07/01/15 10:54 PM
Joined: Mar 2012
Posts: 3,809
C
Cleric Offline
Extreme Tracker
Offline
Extreme Tracker
C
Joined: Mar 2012
Posts: 3,809
that is a hundred thous

ten thous .0001

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5813808 07/01/15 10:56 PM
Joined: Mar 2012
Posts: 3,809
C
Cleric Offline
Extreme Tracker
Offline
Extreme Tracker
C
Joined: Mar 2012
Posts: 3,809
more detail...

Machinist Talk
In general conversations or math class you may hear numbers spoken one way, in a Machine Shop, you may hear the same number described differently for example:

Keep in mind for the following:
In math class everything is based on 1.0
In a Machine Shop using Inch measurements, everything is based on .001" (one thousandths of an inch)

So, how would we say the following?

0.1000
in math class = "one tenth"
in a machine shop = "one hundred thousandths
WHY? because if everything in a machine shop is based on .001 then there are 100 - "thousandths" of an inch

.0100
in math class = "one hundredths"
in a machine shop = "Ten thousandths"

.0010
in math class = "one thousandths"
in a machine shop = "one thousandths" or "one thou"

.0001
in math class = "one ten-thousandths"
in a machine shop = "one tenth"
WHY? because if everything in a machine shop is based on .001 then there is 1/10th of one thousandths of an inch

.00001
in math class = "one hundred-thousandths"
in a machine shop = "Ten Millionths"

Machine Shop examples:
12.3456 = Twelve inches, Three hundred forty-five thousandths and six tenths

0.12345 = One Hundred Twenty-Three Thousandths, Four Tenths and Fifty Millionths

0.5430 = Five Hundred Forty-Three Thousandths

0.0123 = Twelve Thousandths and Three Tenths

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5813819 07/01/15 11:05 PM
Joined: Apr 2010
Posts: 1,228
D
dredd Offline OP
Pro Tracker
OP Offline
Pro Tracker
D
Joined: Apr 2010
Posts: 1,228
So, if I understand what you are trying to say...

You are telling me that he can hold 0.0001 ????

The odds of that being accomplished on an engine lathe with a steady rest are..... way out there, to say the least.
I won't say impossible, but..... darn near.

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5813862 07/01/15 11:24 PM
Joined: Mar 2012
Posts: 3,809
C
Cleric Offline
Extreme Tracker
Offline
Extreme Tracker
C
Joined: Mar 2012
Posts: 3,809
With todays lathe people can run far higher tolerances.

Get a good 4 jaw chuck, mount it right, have a good balanced lathe and its doable easily.

I was running a table top lathe and holding .001 so with better equipment would be no problem

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5813907 07/01/15 11:39 PM
Joined: Dec 2008
Posts: 41,086
J.G. Online Content
THF Celebrity
Online Content
THF Celebrity
Joined: Dec 2008
Posts: 41,086
My gunsmith bud centers to five ten thousandths. Shank and muzzle end alike.


[Linked Image]
800 Yard Steel Range
Precision Rifle Instruction
Memberships and Classes Available
Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5814182 07/02/15 02:16 AM
Joined: Nov 2011
Posts: 4,541
P
patriot07 Offline
Extreme Tracker
Offline
Extreme Tracker
P
Joined: Nov 2011
Posts: 4,541
.010 (+/- .005) should be easy

.005 (+/- .0025) should be do-able for a good machinist on a good machine

Anything tighter than that would have to be done with really good tools on a really good machine by a really good machinst, and it's not going to get a whole lot tighter than that.

Re: Barrel Threading Concentricity Tolerance ???? [Re: patriot07] #5814390 07/02/15 10:17 AM
Joined: Apr 2010
Posts: 1,228
D
dredd Offline OP
Pro Tracker
OP Offline
Pro Tracker
D
Joined: Apr 2010
Posts: 1,228
Originally Posted By: patriot07
.010 (+/- .005) should be easy

.005 (+/- .0025) should be do-able for a good machinist on a good machine

Anything tighter than that would have to be done with really good tools on a really good machine by a really good machinst, and it's not going to get a whole lot tighter than that.


I agree with your post.

I am curious to know what the "world of guns" considers an acceptable tolerance/result.

Is .010 sloppy, or actually tighter than it needs to be for that particular function?

Thanks for the replies.

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5814454 07/02/15 12:12 PM
Joined: Jan 2015
Posts: 2,982
pertnear Online Content
"Demolition Man"
Online Content
"Demolition Man"
Joined: Jan 2015
Posts: 2,982
I'm definitely no expert here, but do extremely close tolerances really matter? I get that we don't want the bullet to touch the sides of a long suppressor, but what is the size of the hole down middle of the suppressor? The bullet is traveling ahead of the hot gases, so long as there is plenty of clearance it doesn't seem too important. Please educate me.

TIA


"Who controls the past controls the future. Who controls the present controls the past.” - George Orwell
Re: Barrel Threading Concentricity Tolerance ???? [Re: pertnear] #5814783 07/02/15 04:10 PM
Joined: May 2009
Posts: 4,242
D
DallasShootingSupplies Offline
Extreme Tracker
Offline
Extreme Tracker
D
Joined: May 2009
Posts: 4,242
.001 is perfectly acceptable. Mine are typically .0005 when I start threading.

.003-.006 likely won't harm the can but will harm accuracy, with can.

I have fixed several that were acting strange with .005ish off center, that other gunsmiths did. Several where THF guys who came to me with erradic groups with cans.

Anything .007-up can cause a baffle strike.

Threading on inside bore is absolutely crucial, lots of pics and vids on my forum post and FB showing how bad off center bores are from the factory. Most recent was an coharie MP5 that was about 25 thousandths off.

Last edited by DallasShootingSupplies; 07/02/15 04:54 PM.

www.class3machining.com
Barrel Threading
50k+ barrels done. Zero Baffle Strikes
www.facebook.com/barrelthreading
www.instagram.com/class_3_machining/
Recommended by Silencerco, Capitol Armory, Hansohn Brothers, Gemtech, Ally Outfitters, The Firearm Blog etc
Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5815826 07/03/15 05:13 AM
Joined: Aug 2009
Posts: 37
S
Stick1 Offline
Light Foot
Offline
Light Foot
S
Joined: Aug 2009
Posts: 37
dredd,

Not sure who you talked to up front, but to clarify, we indicate off the bore to the nearest "tenth" (.0001). It would take a machine beyond special to actually hold that tolerance. We will usually end up around .0005 or less TIR on barrel threads. Hope this clears things up.

-Robert

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5816118 07/03/15 03:35 PM
Joined: Apr 2010
Posts: 1,228
D
dredd Offline OP
Pro Tracker
OP Offline
Pro Tracker
D
Joined: Apr 2010
Posts: 1,228
Robert,

I did not get the gentleman's name.
He mentioned that the Boss had left and he was watching the store front.

I appreciate your reply. It definitely cleared things up. :-)

BTW... I think your store front looked very "clean".
More items than I thought you would have and well laid out.

I'll stop back by when my suppressor comes in.

Thanks,
Brett

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5819367 07/06/15 02:15 PM
Joined: Sep 2009
Posts: 4,755
C
ccoker Offline
Extreme Tracker
Offline
Extreme Tracker
C
Joined: Sep 2009
Posts: 4,755
I don't trust most gunsmith to do threading work.
I do trust Morgan at Dallas Shooting Supplies.
He's fast, does it right and his prices are VERY reasonable.

I had Weatherby do a project for me with two 16" rifles, a 308 and a 7mm08

When I installed my can on the latter it was NOTICEABLY at an angle.
Needless to say, back in the box it went.

As much as cans cost, plus the tax stamp, not to mention the waiting, the last thing I want to deal with is a bad thread job.

Re: Barrel Threading Concentricity Tolerance ???? [Re: dredd] #5819514 07/06/15 04:06 PM
Joined: Dec 2012
Posts: 1,107
C
catslayer Offline
Pro Tracker
Offline
Pro Tracker
C
Joined: Dec 2012
Posts: 1,107
Guys at Alamo are good people. If Robert says it, I believe it...

money slowly building up to pay for a rifle from them..

Last edited by catslayer; 07/06/15 04:06 PM.

Sombody smells like fried borritos...
Re: Barrel Threading Concentricity Tolerance ???? [Re: ccoker] #5820096 07/06/15 09:29 PM
Joined: Mar 2012
Posts: 3,809
C
Cleric Offline
Extreme Tracker
Offline
Extreme Tracker
C
Joined: Mar 2012
Posts: 3,809
Originally Posted By: ccoker
I don't trust most gunsmith to do threading work.
I do trust Morgan at Dallas Shooting Supplies.
He's fast, does it right and his prices are VERY reasonable.

I had Weatherby do a project for me with two 16" rifles, a 308 and a 7mm08

When I installed my can on the latter it was NOTICEABLY at an angle.
Needless to say, back in the box it went.

As much as cans cost, plus the tax stamp, not to mention the waiting, the last thing I want to deal with is a bad thread job.



Not sure I understand your point about gunsmiths and not trusting them. I think it depends on the smith. If they do primarily AR assembly than I could understand. But there are many gunsmiths that I would trust to thread a barrel. Any that do bolt action rifles should be able to that.

Previous Thread
Index
Next Thread

© 2004-2024 OUTDOOR SITES NETWORK all rights reserved USA and Worldwide
Powered by UBB.threads™ PHP Forum Software 7.7.3