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A turning question (Or how to make yourself puke)

H

hockeysew

Aluminum
Joined
Aug 6, 2008
Location
Colorado
Hey all--
Bummer of an experience that I would like to share with you and maybe get some advice from you guys so it doesnt happen again:
One of my customers brought in his Remington 700 Tactical in .223 with a 20" barrel to have the barrel threaded for what I assumed was a muzzle brake.
No problem, chucked the stripped, barreled reciever in my 4 jaw and dialed it in to 0 movement of the indicator. Took the muzzle end with a gage pin in the bore and the barrel supported by the center rest approximatly 1" from the muzzle dialed in the gage pin again to 0 movement of the indicator. Double checked both indicators and all is well. Proceeded to turn down the OD and single point to 1/2 x 28 TPI. Fine.
Get a call today from the customer and he is pissed. Seems the "brake" was actually a suppressor and somewhere along the line something ran out of true with the bore enough that a couple of the baffles and the end of the can blew out from a round striking them.
Now I get to pay for a $600 suppressor and possibly the barrel (He doesnt want it any shorter and I highly doubt he wants me to correct it, let alone look at it.)

After speaking with him I cannot find where I went wrong on my work. I have gone over my procedure mentally and all seems well. I have threaded many barrels and this is the first that has given me a result like this. One thing I did consider, is the diameter of my gage pin too small to get an accurate read?

Thanks and I am open to any suggestions.
 
IMHO, considering the $$ involved I'd want to get the barrel back and do some serious measurements to be sure the problem is you, not the device being screwed on. No measurements, no reimbursement, much less any damages. You might have to make up a concentric female part as a gage, but it sounds like it's worth the effort.

CH
 
Hockeysew:
Center rest? Do you mean steady rest?
First of all did this person make you party to a crime. If he was not legal and meet up with the BATF they would say "Who did this for you?" 1000 times what he paid you would not be worth it.
Back to the problem; Not all gun bores are in the center of the barrel. Have seen some runout .020". If you are using a steady rest 1" from the end of a 20" barrel then you move the 4 jaw until a tight bore pin is true, then for every .001" out of true (barrel od to id) you would have .006" runout over a 6" can. If you want to do this as perfect as possible then turn to tools. First turn a brass bore pin that is centered and turned at the same time. Make it a light tap in fit. Leave a ring so it will not sink all the way into the bore. Then turn a brass or Alu. driver plug that will tightly fit the back 1/3 of the chamber taper and without unchucking hang the barrel between drive plug and a live center. Test by hand that you have torque enought for turning and threading.
Anyone should bore sight these things before they shoot. Look in the chamber end and if you can see anything other than rifling, find out why! Alot of people are trying to make suppressors now days and many can't put that many parts together and keep them all true. The customer sounds like a jerk and he might have even used one for a .22lr might not stand the .223 pressure.
Good luck.
Mike
 
There is also a possibility that there is nothing wrong with either the can or your work. He may have been using some long, heavy bullets that actually had enough yaw and pitch to them as the exited the muzzle to collide with the baffles.

I have seen this happen to a lesser degree to your situation. The customer brought the rifle in, and inspection showed traces of fresh copper on an edge of the muzzle-device. I put a range-rod through the device and into the muzzle until it was tight. The range rod clearly had clearance all the way around, and within the measurement technique we were using, was also centered. When he tried bullet that were just a little shorter and lighter, the problem was gone.
 
He was trying to take advantage of you from the very start. I was in a different business for 40 some years and learned early on, working with expensive material and or tight tolerence items or customers you feel could be a problem all information need to be known up front as all this info must be taken into consideration in pricing the job or deciding not to price it. Make him produce everything like he should have to start with. Cut him no slack as he did you. If your work is within reasonable machining tolerence, he doesn't have much of a claim. You have no way of knowing if it was even screwed on tight. Or "go pee up a rope" Good luck Kenny
 
i am not understanding your setup.

assuming by "center rest" you mean steady rest, there is no way i would use a steady rest on the od of a barrel when threading for a muzzle brake or suppressor. i treat all the threads the same way whether they be the tenon threads at the chamber end, muzzle brake threads or suppressor threads. i use a spider style chuck at both ends of the lathe spindle. the bore gets dialed in using a ptg range rod with a fitted bushing and dialed in TWO spots to a tir of a tenth or less. that is not to say that people don't get away with threading between centers but i certainly don't think it is the best way.

if my lathe spindle bore was too small to fit the barrel though it, then i guess i'd have no choice. i would thread with a center in the muzzle. after the threads were cut, i would place a steady rest on the threads and touch up the crown.


also, if you do indeed mean steady rest, how did you dial in the pin gauge in the bore for zero runout?



edit: like other's have mentioned, there is the possibility you work was not the cause of the baffle strike. it could have been an unstabilized bullet or the suppressor could have been defective. i have to admit though, if i am understanding your setup, i honestly think it is highly suspect.
 
I wouldn't be giving any money back or buying anything for him until I see proof that this happened or that the thread size and pitch is what he said it was. Sounds to me that he was wrong and when ahead and mounted it anyway. Also who's to say that he didn't have a suppressor for a .22 like previously stated. Who's to say that whoever made the suppressor didn't screw up.
I learned my lesson long ago on giving money back. Get proof that you screwed up. Not only for you but the safety of others. I replaced a slide spring on a Beretta Jetfire for a guy, easy enough job right. Well I test fired it. One leg of the spring pops out of the slide. I go back make an adjustment, problem when away. I told the customer about the little issue and that's why it took a couple extra days. Well he was a little ticked that the spring cost 30 bucks. Well it did, I added no mark up I just charge for a install. He calls me a day later all pissed of and demanding his money back for all of it b/c the spring popped out of the side again and he was just going to send it to Beretta. Well regretfully I did send his money back w/o seeing the gun first. Saw him at the range 2 days later shooting that very gun. I told him that customer service from Beretta must be great for liars and I want my spring back now that I see there is nothing wrong. :angry:
Long in short, see proof. Defend your work until proven wrong.
 
Out of curiosity. without the can, how did you determine how long to make the tenon on the end of the barrel? Did the can screw up against a true shoulder?
 
homemade said:
Out of curiosity. without the can, how did you determine how long to make the tenon on the end of the barrel? Did the can screw up against a true shoulder?
Click to expand...

+1

If the tenon was long enough for a typical .223 muzzle break, it could well have caused the suppressor to index against the first baffle instead of the shoulder. That might be fine for some suppressors, but not all are designed with that option.
 
Hey all and Thank You very much for your input. I would like to address a couple of points that were made and I would like to clarify a couple things:

1- I usually do my barrel work through the spindle ala spiders. I did not have that option with this rifle because- A- The headstock is too long on my lathe to allow pass thru on this rifle and -B- The customer was adamant about not wanting the barrel pullled from the reciever.
The only choice I saw at the time was via 4jaw and steady rest.
2- I did not pilot off of the chamber. 4 jaw and dialed the OD just in front of the recoil lug. I shall pilot from the chamber in the future (Never thought about turning a pilot for a specific chamber). I figured if I had any runout at the breech it would be of minimal value at the muzzle
3- Gage pin was inserted in the bore at the muzzle and dialed into 0. I adjusted the runout via the steady rest. I have now fabricated a Cats Head and will use it, I had been using oiled leather to ride on the barrel/steadyrest and I now see how I could induce some error with that method if the leather compressed unevenly. It was never an issue in the past.
4- The owner is a lawfull NFA owner. I never had physical possesion of the suppressor and therefor no regulations were broken.
He is not a jerk and as a matter of fact has helped out at the shop on occasion. He is a good guy. The fact that he is a decent guy has made this a bit easier to deal with. He was pissed when I spoke with him last night and justifiably so. I spoke with him today and he is pretty cool about it and with the pic he sent me the round appears to have just barely clipped the baffles and end cap. I am going to take a look at it Thursday and try to determine what the FUBAR was.
5-When he asked me to thread it I asked what diameter and pitch. His reply was "Same as an AR" I replied to him and actually sketched it out- "1/2 x 28 x .600". He confirmed that was correct and that is what the muzzle was turned to.
6-I am well aware that bores are not always axially aligned/concentric with the barrel. That is why when I do thread a muzzle I zero off of the bore with the gage pin. On a curious note: he sent me a pic of the muzzle device/barrel junction. You can see just a very slight amount of daylight at 12 oclock so it appears that the turn/threads "Droop" very slightly downward. Is this a result of a bore that has runout relative to the barrel? I dunno-At first I thought that maybe the barrel was not aligned axially in the steadyrest but if it was off kilter then the od would be tapered as oppossed to this "droop".
6- Big educational opportunity. In the future I will not thread anything unless I have the muzzle device and suppressor(If it is for a suppressor) in my possesion. That way I can confirm alignment BEFORE delivery to the customer. I cannot possibly have absolute control of the final product if I dont have all the components for the assembley. This is only the 3rd firearm I have threaded for a suppressor and the other 2 were through the headstock and no issues.
7- Probably the biggest lesson for me-NEVER ASSUME ANYTHING! I assumed that it was just for a brake. I think the customer assumed I knew it was for his suppressor.
Communication is key and I shall never take anything for granted again.

Any other suggestions?
 
hockeysew said:
Hey all and Thank You very much for your input. I would like to address a couple of points that were made and I would like to clarify a couple things:

1- I usually do my barrel work through the spindle ala spiders. I did not have that option with this rifle because- A- The headstock is too long on my lathe to allow pass thru on this rifle and -B- The customer was adamant about not wanting the barrel pullled from the reciever.
The only choice I saw at the time was via 4jaw and steady rest.
2- I did not pilot off of the chamber. 4 jaw and dialed the OD just in front of the recoil lug. I shall pilot from the chamber in the future (Never thought about turning a pilot for a specific chamber). I figured if I had any runout at the breech it would be of minimal value at the muzzle
3- Gage pin was inserted in the bore at the muzzle and dialed into 0. I adjusted the runout via the steady rest. I have now fabricated a Cats Head and will use it, I had been using oiled leather to ride on the barrel/steadyrest and I now see how I could induce some error with that method if the leather compressed unevenly. It was never an issue in the past.
4- The owner is a lawfull NFA owner. I never had physical possesion of the suppressor and therefor no regulations were broken.
He is not a jerk and as a matter of fact has helped out at the shop on occasion. He is a good guy. The fact that he is a decent guy has made this a bit easier to deal with. He was pissed when I spoke with him last night and justifiably so. I spoke with him today and he is pretty cool about it and with the pic he sent me the round appears to have just barely clipped the baffles and end cap. I am going to take a look at it Thursday and try to determine what the FUBAR was.
5-When he asked me to thread it I asked what diameter and pitch. His reply was "Same as an AR" I replied to him and actually sketched it out- "1/2 x 28 x .600". He confirmed that was correct and that is what the muzzle was turned to.
6-I am well aware that bores are not always axially aligned/concentric with the barrel. That is why when I do thread a muzzle I zero off of the bore with the gage pin. On a curious note: he sent me a pic of the muzzle device/barrel junction. You can see just a very slight amount of daylight at 12 oclock so it appears that the turn/threads "Droop" very slightly downward. Is this a result of a bore that has runout relative to the barrel? I dunno-At first I thought that maybe the barrel was not aligned axially in the steadyrest but if it was off kilter then the od would be tapered as oppossed to this "droop".
6- Big educational opportunity. In the future I will not thread anything unless I have the muzzle device and suppressor(If it is for a suppressor) in my possesion. That way I can confirm alignment BEFORE delivery to the customer. I cannot possibly have absolute control of the final product if I dont have all the components for the assembley. This is only the 3rd firearm I have threaded for a suppressor and the other 2 were through the headstock and no issues.
7- Probably the biggest lesson for me-NEVER ASSUME ANYTHING! I assumed that it was just for a brake. I think the customer assumed I knew it was for his suppressor.
Communication is key and I shall never take anything for granted again.

Any other suggestions?
Click to expand...

If you have the suppressor in your possesion, is the owner going to stay in the room with it? I'm not trying to be a smart ass, just trying to get a feel for how these regs work. I've had a few people approach me about barrel threading for their accesories, not covering what exactly they were, and I back away from it because of not being clear on what I can or cannot legally do. Of course, I don't do gun work for a living, mainly only my own for the last few years.
 
Any other suggestions?
Click to expand...

It would be interesting to turn up a known true facsimile of the end of the barrel and screw the can on to look for daylight. May not prove anything at this point but the fixture would be nice to have in the drawer. Next time indicate it in the four jaw, screw on the can spin it up and watch for wobble on the far end may just prove or disprove the can before you touch the barrel.
 
homemade said:
It would be interesting to turn up a known true facsimile of the end of the barrel and screw the can on to look for daylight. May not prove anything at this point but the fixture would be nice to have in the drawer. Next time indicate it in the four jaw, screw on the can spin it up and watch for wobble on the far end may just prove or disprove the can before you touch the barrel.
Click to expand...

i would do something similar to check my work first. in one setup, i would face the end of some stock, single point thread the id to match the muzzle, turn the od and then part it off a few inches long. using a 4 jaw and rear spider (and yes, i would remove the barrel from the receiver if i had to in order to check my work before i payed out $600+), i would then dial in the barrel bore at two spots to a tenth or less with a tapered range rod and fitted bushing. without changing anything, i'd thread on the tool made earlier and measure the runout at a couple spots. if you used a steady rest on the od of the barrel, i will almost guarantee that there is going to be quite a bit of runout.


if you wanted to check the suppressor, you could turn and single point an od thread to match the suppressor. without moving your setup, you could thread on the suppressor and measure the runout at the exit hole of it. i imagine that is going to be quite a bit tougher after a baffle strike though.
 
I've been thinking about this, and I can't see where you made a mistake with the set-up. True, the C/L of the bore isn't always in line with the outside of the barrel, but you covered that by indicating a pin inserted into the muzzle. That should have been "close enough" for what you were asked to do, thread for a flash hider.

I don't have much experience with cans, but usually these have a threaded adapter that fastens to the muzzle threads, then the can attaches to the adapter. Has anyone investigated the alignment or the fastening of the can to adapter?

Now that there is damage, it's going to be hard to do the detective work.

If your customer isn't going to allow you to check the damage, or give you the opportunity to make it right other than just pay a bill, it's going to be as hard for the customer to prove that there was a defect in your work, as it is for you to prove there wasn't some negligence on the customers part.

Something isn't being fully disclosed here. What is it?

Mark H
 
I don't have the guts to thread my own bbls, I have sent them to Tornado Technologies with good luck. Not worth it to DIY and blow the end cap off a $500-1500 can plus the damn NFA stamp. AFAIK he is indicating off the bore in a double spider set up and making about 15-20 cuts on the threads. He just chopped and threaded my 50 cal and it is beautiful. Not sure but some can mfgrs. won't warranty a can if it is not threaded by someone one their list.

Here's the 50.

Before..

gunpics007.jpg


After...

50bmgpics006.jpg


Crappy up close...

50bmgpics016.jpg


50bmgpics001.jpg


$150 and he said it was a pain to jig up due to the bbl length and receiver dia.
 
Mark H said:
I've been thinking about this, and I can't see where you made a mistake with the set-up. True, the C/L of the bore isn't always in line with the outside of the barrel, but you covered that by indicating a pin inserted into the muzzle. That should have been "close enough" for what you were asked to do, thread for a flash hider.

I don't have much experience with cans, but usually these have a threaded adapter that fastens to the muzzle threads, then the can attaches to the adapter. Has anyone investigated the alignment or the fastening of the can to adapter?

Now that there is damage, it's going to be hard to do the detective work.

If your customer isn't going to allow you to check the damage, or give you the opportunity to make it right other than just pay a bill, it's going to be as hard for the customer to prove that there was a defect in your work, as it is for you to prove there wasn't some negligence on the customers part.

Something isn't being fully disclosed here. What is it?

Mark H
Click to expand...


he thought he was threading for a muzzle brake. a muzzle brake can be a couple inches beyond the muzzle and only .020" over the bullet diameter. in my opinion, threading for a muzzle brake should be done to the same standards as threading for a suppressor.

i am still not understanding how he got rid of the bore runout with a steady rest riding on the od of the barrel. if the bore is perfectly concentric to the od of the barrel (probably extremely rare), then there would not be any runout using a steady rest. a steady rest doesn't adjust for runout. it can be adjusted in a way that will cause a taper though and still show minimal runout on a pin gauge. i am really finding it hard to believe that there was 0 tir on a pin gauge in the bore with a steady rest riding on the untrued od of the barrel.
 
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