Is this suppose to hang to the right?

[jebs]

I am not sure how many barrel manufacturers are putting the holes in their barrels these days. Perhaps the norm for many is to use some of the new exotic HSS or Carbide deep-hole drill bits or inserted drill blanks - But I seriously doubt that; Because where I work we are pushing the envelope at what can be done using both of the above to the maximum depth possible at the highest rate of feed achievable thru tool steels over 62 Rc.

Having said that , I seriously doubt barrel manufacturers have invested the money required to keep up with what we can do. They almost have to be using gun drills, which
are by far the best way available to put deep, straight, precise, & smooth holes thru long distances. Nothing else can come close to what a gun drill can do, especially on a cost scale.

A gun drill is not really a "drill", as one would think of when they look at a common drill bit as seen on the shelf at Lowes or Homeless Depot. Yes, it is a "drill" in the sense of how it rotates & advances thru the material, removing it as it goes. But, they look nothing like a common drill bit. The secret of a gun drills performance is in the end geometry of the cutting portion of the bit. If this geometry is off in any way, or dull to a certain degree, all bets are off as to how good of a hole you will get. Back in the early '80s, we routinely gun drilled 0.5000" diameter holes 10 feet deep with less than 0.0007" circular runout & concentricity from end to end thru stainless steel in less than 20 minutes.

Perhaps you just got a bad barrel, or when the barrel extension was put on it, someone forgot to indicate it concentric to the bore or vise-versa.

[explorecaves]

Thank you for the lesson. I am only familiar with typical CNC operations, not the obviously specialized drilling needed for barrels.

[LRRPF52]

Are the threads off center from the bore and OD, or the OD and threads off center from the bore?

[ricsmall]

LR52,

Looks like the threads and crown are eccentric to the bore.

Richard

[Chrazy-Chris]

This is an example of barrel run-out, yes? When the bullet jumps into the rifling and then all of a sudden is diverted down this crooked hole - poor accuracy results. Trust me, I heard this in a podcast on the internet.

PS the title of this thread is still cracking me up ... I was a little afraid to open it

[Texas]

I would be very interested in knowing how the company is making barrels, because this would be extremely difficult to do with CNC machines.
The first thing that is done to a barrel blank is to machine a reference surface , on the M4 barrels, this was 8 inches.
Once the reference is machined, the reference is used by the long bore gun drill to bore the hole through the barrel.
Once the barrel is bored, the reference is used to chamber and profile the barrel. In our case this was three separate CNC machines, but all measurements were taken from the reference to ensure concentricity and profile measurements.
this appears to be manually done on at least two machines or the same machine chucked twice with no standard reference.
A real hit or miss chance for accuracy, more of a miss

[The Profit Joseph Sith]

Was anyone else scared to open this thread based on the title?

Yes.. but why should doctors have all the fun
Jebs welcome aboard.
Are the "gun drills" to which your referring zero margin bits? As in spiral ground with no flutes, probably carbide tipped?
Just curious. Boeing uses them fairly often. Not fr deep hole though. I have been looking for a supplier ever since. They can be very handy. I think Pacific made them but don't sell them to the public.

I'm certainly no expert, but wouldn't edm bored holes be the most accurate In every dimension over boring? I'm sure it wouldn't be the most cost effective or timely process but just curious. I used to make carbide bits for swift tool. FWIW. I have a feeling that's how they cut their coolant passages through the inside of their end mills. How else would you cut spiral passages through carbide blank accurately? There's alot of cool things EDM can do.

[LR1955]

MT:

Who made the barrel?

These things upset me to no end because once again a company does a poor job, knows it is a poor job, and lets it go out the door anyway. There is no way anyone doing a visual inspection could miss this major defect.

So the barrel maker sells this POS to someone who again knowingly puts it on a upper and sells it to the public. Or the barrel was sold to a basement upper builder who knows it is bad but installs it anyway.

All of the above sellers know that they can sell ten of these inferior quality barrels and only one person will argue with them enough to get a new barrel. And it will be an argument, too.

It is a good thing to tell us who made the barrel and who sold it to you so we can make some decisions before buying from them.

LR55

[The Profit Joseph Sith]

MT:

Who made the barrel?
LR55

Ya I'm REALLY curious as well. Either maker or supplier.

[jebs]

Yes.. but why should doctors have all the fun
Jebs welcome aboard.
Are the "gun drills" to which your referring zero margin bits? As in spiral ground with no flutes, probably carbide tipped?
Just curious. Boeing uses them fairly often. Not fr deep hole though. I have been looking for a supplier ever since. They can be very handy. I think Pacific made them but don't sell them to the public.

I'm certainly no expert, but wouldn't edm bored holes be the most accurate In every dimension over boring? I'm sure it wouldn't be the most cost effective or timely process but just curious. I used to make carbide bits for swift tool. FWIW. I have a feeling that's how they cut their coolant passages through the inside of their end mills. How else would you cut spiral passages through carbide blank accurately? There's alot of cool things EDM can do.

Sith,

I am not sure what zero margin refers to; I have never heard that term used in Tool & Die/Mold making. True deep-hole gun drill "bits" are really just chunks of carbide sintered/soldered on to a tube that the coolant (oil) flows thru. The O.D. of the carbide is sized
to what you want the bore to finish at. The angles on the end have radial rake (clearance). There are no flutes at all like a normal drill bit. They are almost like a spade drill on the end. What drives their accuracy is the length and angle of each "leg" of the cutting end of the bit, from the center to the O.D. - That, and of course, as with all other drilling types - speeds & feeds & flushing. Push it too fast, and you get bad results... Push it too slow, and you get reduced tool life & chatter etc etc.

EDM can do some good things, but it would be a very very very special production setup
if one were to try to burn holes that deep. An existing hole of smaller-than-finish-bore-diameter would have to exist before the EDM could do its work - the flushing would have to be sucked or pulled from the end of the 'trode towards the bottom of the bore & the 'trode breakdown at those depths would be atrocious.

Regarding the coolant holes in the end mills - If those are solid carbide, my guess would be that the holes were formed by a sacrificial solid round core of some type during the formation of the carbide solid blank (Akin to ceramic cores in lost-wax process).

[hikfromstik]

It's alwasys been a wise tale to the consumer that Monday's and Fridays are the days that automobile factories have the most lemons due to Monday hangovers and Friday weekend jitters . Maybe this could be the case here or maybe the greenhorn apprentice took his first jab on the deep bore drill . Ditto on who is the barrel (blank) manufacturer ?

[The Profit Joseph Sith]

A standard brill bit is single margin as in one flute, double margin is like a single margin but with two flutes. One on the leading edge one on the trailing edge of the spiral. A zero margin has no flutes what so ever... They ONLY cut on the front end "point" of the bit. Exactly like modern day gun drills. From what I understand the zero margin bits used to be used for these processes instead of the modern day style and zero margin bits are still commonly referred to as "gun brill bits" though the true technical name is a zero margin.
I am familiar with modern day gun drills and have seen many a barrel made. I figured that's what you were referring to but I wanted it clarified.

Hole drilling can be pretty scientific.
And I get the feeling you might be thinking I was referring to wire edm. Which maybe I'm wrong but I was referring to the kind that uses an electrode underwater to sorta peck the material away much like milling with a bit. Just using errosion. I do agree that you'd want a relief hole anyway though to allow the gasses out. I've heard they do make barrels by edm process though. I think EFK is one of them if I remember correctly.

[jurassic]

I had a Remington Model Seven that looked exactly like your picture only I did not know what was wrong with the rifle until several boxes of ammo had been shot trying to sight in. It sprayed bullets everywhere , and drove me mad thinking my scope had something loose inside. Needless to say that rifle went back to the gun store.

[jebs]

A standard brill bit is single margin as in one flute, double margin is like a single margin but with two flutes. One on the leading edge one on the trailing edge of the spiral. A zero margin has no flutes what so ever... They ONLY cut on the front end "point" of the bit. Exactly like modern day gun drills. From what I understand the zero margin bits used to be used for these processes instead of the modern day style and zero margin bits are still commonly referred to as "gun brill bits" though the true technical name is a zero margin.
I am familiar with modern day gun drills and have seen many a barrel made. I figured that's what you were referring to but I wanted it clarified.

Hole drilling can be pretty scientific.
And I get the feeling you might be thinking I was referring to wire edm. Which maybe I'm wrong but I was referring to the kind that uses an electrode underwater to sorta peck the material away much like milling with a bit. Just using errosion. I do agree that you'd want a relief hole anyway though to allow the gasses out. I've heard they do make barrels by edm process though. I think EFK is one of them if I remember correctly.

Sith,

Yes, they would be referred to as zero margin in that usage of the terminology. They only cut on the front.

Oh goodness no, I would never confuse the Wire EDM with the Plunge or Sinker EDM. I have ran both since the early '80s, with thousands of hours on each. The pre-existing hole would have to exist for two reasons...
1) In a deep thru-hole like a barrel, you would have to pull the swarf thru from top to bottom in order to maintain accuracy - Any attempt to force flushing from the top to bottom will make the 'trode wander off of a true vertical path
2) DC Arcs would be the death-knell to a barrel bore - These are best prevented by pulling from the top to the bottom

Although an interesting concept, it could never catch on or surpass the mainstream usage of conventional gun drill bits. What would kill it would be the time required to complete the burn from top to bottom, and the problem of maintaining a fresh electrode that would have to be within 0.0001" runout for at least 3" of length & mounted on something about 18" long. It could be done, but as you said, it would be too cost-prohibitive & the gun drill would win the race. The only justification I could see for it would be if you wanted a barrel made out of M-2 at 63 Rc. or Ferrotec or DC53. (I am glad someone else other than me is doing it - I would not want that headache) .

EDIT: Ah, I just went & checked out the EFK website. It looks like they specialize in match-grade barrels for pistols. That length is short enough
to be done with a 'trode, but I would think they still conventional drill or gun drill the barrels & then do the riflings by what they are calling electro-chemical laser rifling. That seems to be quite different from conventional plunge EDM. They probably do the porting by conventional EDM - You can throw quite a few bucks at end mills required to cut the ports, or you can choose to throw your money at graphite for electrodes.

[Texas]

Yes.. but why should doctors have all the fun
Jebs welcome aboard.
Are the "gun drills" to which your referring zero margin bits? As in spiral ground with no flutes, probably carbide tipped?
Just curious. Boeing uses them fairly often. Not fr deep hole though. I have been looking for a supplier ever since. They can be very handy. I think Pacific made them but don't sell them to the public.

I'm certainly no expert, but wouldn't edm bored holes be the most accurate In every dimension over boring? I'm sure it wouldn't be the most cost effective or timely process but just curious. I used to make carbide bits for swift tool. FWIW. I have a feeling that's how they cut their coolant passages through the inside of their end mills. How else would you cut spiral passages through carbide blank accurately? There's alot of cool things EDM can do.

Here are what we used to make barrels up to 45 inches. http://www.sterlinggundrills.com/pri...ngle-flute.php

We used a Nagel long bore drill with the barrel turning one direction and the drill turning another. It would bore three barrels at a time.