Barrel Threading

[SWShooter]

Here`s how these guys do it https://www.youtube.com/watch?v=JV6jTZzsNBw

[nthnmunky]

Nice video. I'd love a lathe and milling machine etc.

[Big Al]

The guy wouldn't be getting my business, I lost interest when he clocked the barrel up on the outside diameter rather than the bore, I guess cutting the crown perpendicular to the bore isn't of significance to him.

[SWShooter]

The guy wouldn't be getting my business, I lost interest when he clocked the barrel up on the outside diameter rather than the bore, I guess concentricity to the bore isn't of significance to him.

 

I doubt it makes any difference with a muzzle break which is what he fitted , this clip shows how far out barrels can be https://www.youtube.com/watch?v=7duvo7XLWIs

[Danpd]

 

I doubt it makes any difference with a muzzle break which is what he fitted , this clip shows how far out barrels can be https://www.youtube.com/watch?v=7duvo7XLWIs

 

It certainly does make a difference.

[SWShooter]

 

It certainly does make a difference.

 

Do explain , if the bullet makes no contact it will still affect the flight path?

[Big Al]

 

Do explain , if the bullet makes no contact it will still affect the flight path?

 

If the threads are cut after clocking the outside of the barrel rather than the bore then there is no guarantee that the crown will cut perpendicular to the bore, as such the bullet will lose the support of the rifling at different times, this will make the bullet yaw and accuracy will suffer.

[baldie]

Unbelievable.

 

A fantastic video of exactly HOW NOT to thread a muzzle. Its completely irrelevant what is getting screwed onto it, clocking the barrel O/D and not the bore is completely wrong, and totally unsafe.

[bradders]

I'll bet you all that that's how most barrels in the world are threaded, with few detrimental side effects

300 million guns in America, they aren't all custom match rifles you know

[andybrock]

I'm not a machinist but shouldn't he be using a coolant / lubricant when threading etc or don't you need to?

[gbal]

I'll bet you all that that's how most barrels in the world are threaded, with few detrimental side effects

300 million guns in America, they aren't all custom match rifles you know

The modal best selling rifle currently made in USA is probably the AR15 223 clone ( even in the Obama Barracks).

 

"Custom bench rest class rifles" are probably about (a decent 100Yard BR group)% of sales.

 

gbal

[Ronin]

Have to agree this is a glaring example of how not to....

 

Barrel "clocked" on the OD - how far out from the centre of the boreline is the O/D of the barrel ?

 

Who knows but its usually .010" - .030" even on good "quality" barrels

 

So the centre of bore line of the brake is immediately off centre of the bore of the barrel.

 

Usually one would clock off the O/D of the barrel to get the OD of the brake the same and "seamless"

 

So now, unless the brakes bore is massively over bore size there will be a difference in pressure as the gasses and bullet pass through the brake, affecting accuracy detrimentally.

[Big Al]

I'll bet you all that that's how most barrels in the world are threaded, with few detrimental side effects

300 million guns in America, they aren't all custom match rifles you know

 

Im sure you are right bradders in respect of general accuracy but if your paying for custom shop work then I would expect the bore to be clocked, all other things being equal it certainly wouldn't make the rifle less accurate.

 

The whole concept of working tolerances and how they ultimately affect accuracy is something that interests me but something you can find very little information about. We have all seen guys showing clocked chambers with zero run out but nobody seems to know exactly how much run out you can get away with whilst still having a precision rifle, that would also apply at the other end with the crowning. A perfectly perpendicular crown that is badly cut for example will be less accurate than one cut properly and clocked on the outside of an average barrel I would guess.

 

My impression is that many gunsmiths dont really know exactly what lesser tolerances will still produce a high standard of results and as such just strive for near perfection with the attitude that it wont do any harm.

[Ronin]

Lesser tolerances = shoddy work = inaccuracy

 

If the jobs isn't 100% then it isn't going out of my workshop.

[Big Al]

Lesser tolerances = shoddy work = inaccuracy

 

If the jobs isn't 100% then it isn't going out of my workshop.

 

No, that isn't correct Im afraid.

 

Lesser tolerances than some of the stuff Ive seen gunsmiths claim doesn't mean you get an inaccurate rifle. There are plenty of factory rifles that shoot very well indeed with less than perfect concentricity and tolerances. The likelihood is that the quality of the barrel itself is what lets it down in terms of competing with the true custom builds and much less to do with the tolerances used in its manufacture. This 'anything less than 100% isn't leaving my workshop' is just marketing jargon from people who more often than not haven't worked in real engineering.

 

I worked in high precision engineering and served my time in a very highly skilled environment within the medical sector, do you think we worked to +/- 0 all the time and anything less than that was shoddy work? - everything has workable tolerances, some are just smaller than others. The point Im trying to make here is that there will be a perfectly workable tolerance that will produce a highly accurate rifle and it will be way bigger than the 0.0005" I see so many people talk about, yourself included.

 

I would have far more respect for you as a gunsmith if you were able to tell me at what point accuracy starts to suffer due to the widening of tolerances and then by how much, rather than to say anything less than 100% wont be the most accurate. Clearly we all know less than 100% will still create a rifle capable of very high levels of accuracy. I also know that its very unlikely you always work to 100% - I would construe 100% as engineering perfection, with all due respect if your suggesting you or your machinery are capable of achieving this every day then you are kidding yourself and those who believe you.

 

Ive said this to you before, I respect anyone who tries to do a job to the best of their ability and if you want to spend lots of time getting the clocks to read as near to zero as you can then again I respect you for that. I also respect the fact that clearly you have built rifles for guys that are very accurate. I would however suggest that this probably had more to do with high quality component selection than engineering perfection? I accept your trying your best to get as close as you can to perfection, whether or not this really matters is the point in question?

 

 

To describe working to lesser tolerances as shoddy is naive.

[Big Al]

Duplicate post removed.

[Offroad Gary]

Whats wrong with chinese lathes?

[Ronin]

Fair comment you have raised the point before.

 

 

The fact is I do not advertise for work - so really it makes no difference to me if I get work or not.

 

 

If I have the time to conduct a test if what makes a difference to accuracy, then i'll try to, but it wouldn't hold much water as it would be neither scientific or would I have the time or finances to spend on doing several so an "average" of when tolerances impart a negative effect on accuracy.

 

I believe the definitive tome on what affects accuracy is Harold Vaughns book - rifle accuracy, the facts - there is a great deal of relevant information there.

 

 

For what its worth when I say if I'm not 100% happy with an item , it doesn't leave my workshop, I mean that everything is done to my expectations (which are high) this includes next to 0 run out when setting up barrels in the lathe, machining to size, threading to spec, chambering to as low a run out as possible etc etc etc

 

 

I dont charge a great deal for my work, I don't need the extra money, so its not an advertising speil as you kindly suggest it is and for the record I worked for an engineering company for a number of years which worked within the nuclear industry.

 

 

If you want a rifle that shoots consistently accurately, id suggest you wouldn't find it from something which the chamber has excess headspace, eccentric tenon alignment and a offset crown (as I've seen on several factory and other guns)

 

You may find the rifle shoots occasionally well "minute of deer" perhaps, if thats your thing, I prefer to have something I've the confidence in to know has been put together well and has everything in place to shoot accurately and consistently.

[243ack]

+/- 0 just isn't attainable.

All dimensions should be specified with a tolerance.

Machines are not perfect, nor are the electronics controlling them, or the operators programming them.

[Ronin]

Sorry,

 

you're saying isn't not possible to machine a barrel tenon to a specified diameter.....

 

1.0625" dis the standard diameter for most remington base actions (both custom and those from the "big green") - you're saying its not possible to machine to that size....?

 

Ive just (literally) machined a tenon for a tikka the diameter for the tenon is .998" diameter and .987" long, both measurements are exact recorded on Mitutoyo digital equipment - with calibration certificates

 

 

Are you saying that these measurements are not correct....and its impossible to work to ?

[243ack]

Ronin - if the previous was aimed at me - then yes: I am saying it is impossible to machine to an absolute dimension. If three decimal places is your idea of 'asolute' then OK - and I'm sure it is more than adequate for two century old devices.

I would suggest, though, that for some modern disciplines (not riflecraft), 3 places would be considered quite rough!.

[The Gun Pimp]

Interesting discussion. Just what matters - accuracy-wise?

 

Undoubtedly, the most proven accurate rifles are the short-range 6PPC benchrest rifles. If factory rifles can be as accurate - why don't we see them in the winner's circle?

 

In 20 years shooting benchrest, I've seen a familiar progression - newby comes along with a factory rifle, tunes his load, learns to shoot in the wind and eventually consistently shoots under half MOA. After a couple of seasons, our shooter wants more - so rifle is fitted with a custom barrel and groups shrink even more. If he's still hungry, he goes for an all-out 6PPC custom gun - wow, now he really has an accurate rifle and he knows how to use it - he stands in the winner's circle.

 

Yes - we can discuss what makes an accurate rifle and how much the odd thou. here and there really matters but, you will only get that 'one holer' if everything is spot-on. There is no room for 'near enough'.

 

However, you can occasionally get that 'one in a million' factory rifle. I remember 'Bald-headed Gordie' and his 308 Remmy 1000yd BR gun, Laurie's 204 Savage, Stu Benson's 1000yd Remmy, 'Foxing tonight' and his 6.5 AI - to name but four.

 

Yes - I know there will be the "I've got a factory rifle that shoots quarter MOA all day long..." OK - put up or shut up - come and show us in competition. There's a hell of a difference plinking away and turning in the odd good group, to sitting down in a BR match and doing it there and then in seven minutes.

[Ronin]

Ronin - if the previous was aimed at me - then yes: I am saying it is impossible to machine to an absolute dimension. If three decimal places is your idea of 'asolute' then OK - and I'm sure it is more than adequate for two century old devices.

I would suggest, though, that for some modern disciplines (not riflecraft), 3 places would be considered quite rough!.

 

 

Pretty much negating your argument with the comment above then.

 

The barrels are set up to run at or as close to zero run out as I am able to before and during the machining process (that means I check and just if necessary at each stage)

 

Its not in a temperature controlled environment using laboratory equipment.

 

The product I and several others who post on here and rifle builders who don't but are based in the UK create is more than "adequate" to produce repeatable, consistent accuracy.

 

 

The original post is an ideal demonstration of "how not to"

 

If you or some other posters would be happy with that persons idea of machining your barrels, then I'm sure the chap will happily take your coin.

[Laurie]

Yes - I know there will be the "I've got a factory rifle that shoots quarter MOA all day long..." OK - put up or shut up - come and show us in competition. There's a hell of a difference plinking away and turning in the odd good group, to sitting down in a BR match and doing it there and then in seven minutes.

 

 

 

............. and doing it five times in the course of a day's competition over a maybe seven hour period, the times and range / weather conditions not chosen by the shooter but dictated according to the squadding arrangements and working through the relays.

 

If it's a good factory rifle with good handloads it'll be fun and competitive in class, but as Vince says the very carefully built custom BR guns are in a different league. I've got to say that I find the implication of some posts on this topic that you can go out and buy a load of quality components and have them 'smithed' by some chancer who knows jacksh*t about precision gunsmithing and cares as little ludicrous. There are plenty of high-spec rifles around that don't perform.

 

Whether there is a benefit in getting the tolerances down from where we are now to the micron level is a legitimate debatable point. Every construction activity has a point of diminishing or zero returns. The best gunsmiths may well be there now.

[1967spud]

Interesting discussion. Just what matters - accuracy-wise?

 

Undoubtedly, the most proven accurate rifles are the short-range 6PPC benchrest rifles. If factory rifles can be as accurate - why don't we see them in the winner's circle?

 

In 20 years shooting benchrest, I've seen a familiar progression - newby comes along with a factory rifle, tunes his load, learns to shoot in the wind and eventually consistently shoots under half MOA. After a couple of seasons, our shooter wants more - so rifle is fitted with a custom barrel and groups shrink even more. If he's still hungry, he goes for an all-out 6PPC custom gun - wow, now he really has an accurate rifle and he knows how to use it - he stands in the winner's circle.

 

Yes - we can discuss what makes an accurate rifle and how much the odd thou. here and there really matters but, you will only get that 'one holer' if everything is spot-on. There is no room for 'near enough'.

 

However, you can occasionally get that 'one in a million' factory rifle. I remember 'Bald-headed Gordie' and his 308 Remmy 1000yd BR gun, Laurie's 204 Savage, Stu Benson's 1000yd Remmy, 'Foxing tonight' and his 6.5 AI - to name but four.

 

Yes - I know there will be the "I've got a factory rifle that shoots quarter MOA all day long..." OK - put up or shut up - come and show us in competition. There's a hell of a difference plinking away and turning in the odd good group, to sitting down in a BR match and doing it there and then in seven minutes.

WELL PUT