Pre bore the chamber results?

[Edd]

For starters I am not young and the gentleman in question has been a machinist for 30 +years and runs some high dollar equipment think 6 figures plus. The company he works for builds precision parts.

They do not let guys that don't know what they are doing run machines like that or build precision parts on them with million dollar contracts on the line.

You are assuming a lot that you can straighten that hole better than the barrel maker who made it who more than likely has better tools, gauges, and so on our you would be making your own barrels.

How do you know it is off in the first place? Sure all bores curve but you what looking at 3 to 5 inches or less in depth from when they started the hole to just about any throat out there.

You are going to tell me a high quality barrel maker in this day and age does not have that hole in that short of a distance dead nuts? Really?

Pre boring was designed for one reason so a gunsmith could save on reamer wear period.

If its the end all be all why is a guy like Robert Gradous not doing it?

Let me guess Robert does not know that a hole can be straightened right?

Like I said the theory is flawed you are assuming the bore is already off so you need to go in and line the chamber up to it.

If you are really convinced that hole is off why chase the hole than run a boring bar? Why not just start with the boring bar and skip the drill bit?

You are also assuming you are not getting any tool deflection because of light cuts but your cross feed does have any deflection or the boring bar or tool holder right?

I did not learn from a rifle builder I learned from a machinist and shooter who has done really well in the shooting world and guess what he does not pre bore either.

So you want to pre bore go for it. You want to chuck it up in a 4 jaw and just dial the throat in and never mind the wobble on the back half, Cut the threads and chamber knock yourself out.

But do not try and tell me its more accurate than dialing in the throat and breach in and then running a reamer in because the results I see and thousands others see doing it this way speak for itself.

I don’t think you understand the complete process. Drilling and pre-boring allows a third point to be dialed in. If the muzzle and the throat are dialed in, the back end of the barrel will not be. After the drilling and boring, it will be.

 

[urbanrifleman]

Sir, I believe only a very few on this forum could fit in Jackie's shoes.

I certainly am not taking anything away from his skills which seem to be incredible. I hope no one thinks otherwise.

 

[WSnyder]

I don’t think you understand the complete process. Drilling and pre-boring allows a third point to be dialed in. If the muzzle and the throat are dialed in, the back end of the barrel will not be. After the drilling and boring, it will be.

You can only align two points at a time not three. By drilling and boring you can bring the breech in alignment with throat and muzzle. By doing that you can now have three points in alignment but you didn't dial it in using three points (unless you got really lucky on that barrel ).

In my quick skimming of his (dakor) method he is aligning the throat and breech (in such a short section there is likely little runout) and allowing the muzzle to be where it is. Similar methods are used often and are well known.

 

[jackieschmidt]

You can only align two points at a time not three. By drilling and boring you can bring the breech in alignment with throat and muzzle. By doing that you can now have three points in alignment but you didn't dial it in using three points (unless you got really lucky on that barrel ).

In my quick skimming of his (dakor) method he is aligning the throat and breech (in such a short section there is likely little runout) and allowing the muzzle to be where it is. Similar methods are used often and are well known.

^^^^^^
Most know that is exactly how I establish my chambers in my barrels

If the ID’s of barrels were dead straight, this would all be a moot point. But they are not. So that leaves the craftsman options as to how he will establish his third point, (that being the chamber), truly straight with two other predetermined points.
I agree, many do use what is commonly referred to as the “Gordy Method” where you true a short section of the barrel at the chamber end in two points. This does give you, more or less, a straight hole that the reamer will follow.

But it also creates a problem. What to do with that muzzle end that might be pointing in gosh knows what direction. Many “clock” the barrel so it is pointing up, some say down is better. (No one says sideways).

I just avoid all of that. I true the muzzle, core out the chamber with a drill, then reach in with an indicator and indicate the first thing the bullet “sees” as it leaves the case mouth. That’s two points dead straight with each other. I then single point bore the drilled hole on the same taper as the case within a predetermined size for finished reaming. That’s the third point. I then establish the best chamber possible and work everything else off of that.

This is jus standard machine shop practice.

 

[dakor]

^^^^^^
Most know that is exactly how I establish my chambers in my barrels

If the ID’s of barrels were dead straight, this would all be a moot point. But they are not. So that leaves the craftsman options as to how he will establish his third point, (that being the chamber), truly straight with two other predetermined points.
I agree, many do use what is commonly referred to as the “Gordy Method” where you true a short section of the barrel at the chamber end in two points. This does give you, more or less, a straight hole that the reamer will follow.

But it also creates a problem. What to do with that muzzle end that might be pointing in gosh knows what direction. Many “clock” the barrel so it is pointing up, some say down is better. (No one says sideways).

I just avoid all of that. I true the muzzle, core out the chamber with a drill, then reach in with an indicator and indicate the first thing the bullet “sees” as it leaves the case mouth. That’s two points dead straight with each other. I then single point bore the drilled hole on the same taper as the case within a predetermined size for finished reaming. That’s the third point. I then establish the best chamber possible and work everything else off of that.

This is jus standard machine shop practice.

I use a viper fixture since the viper is the one that taught me how to chamber and thread a barrel. I use a rod with a bushing on it to dial in the throat and breach to less than 2 tenths runout. I do not care what the muzzle is doing as it has no effect on what I am doing.

This worked for Bob and It works for me.

I can already hear the backlash about this but I only time a barrel if its fluted and I am matching the flutes with the stock line.

Other than that its a complete waste of time and has no effect on anything.

That bore is not going to be in xyz position by the time the bullet leaves.

Barrels like arrows flex in every direction when they are fired. There are plenty of slow motion videos like this one showing this.

So that barrel is moving all over the place as that bullet travels down the bore.

Putting the barrel so the curve is a certain way makes no difference because it is not going to be aligned the way you had it when the bullet starts its way down.

Add a brake or Supressor on the end and the flex increases.

 

[jackieschmidt]

I use a viper fixture since the viper is the one that taught me how to chamber and thread a barrel. I use a rod with a bushing on it to dial in the throat and breach to less than 2 tenths runout. I do not care what the muzzle is doing as it has no effect on what I am doing.

This worked for Bob and It works for me.

I can already hear the backlash about this but I only time a barrel if its fluted and I am matching the flutes with the stock line.

Other than that its a complete waste of time and has no effect on anything.

That bore is not going to be in xyz position by the time the bullet leaves.

Barrels like arrows flex in every direction when they are fired. There are plenty of slow motion videos like this one showing this.

So that barrel is moving all over the place as that bullet travels down the bore.

Putting the barrel so the curve is a certain way makes no difference because it is not going to be aligned the way you had it when the bullet starts its way down.

Add a brake or Supressor on the end and the flex increases.

The late Gene Bukys chambered his barrels using exactly the same method. Heck, all he ever did was win a a World Championship, the Supershoot, and shoot his way in to the Benchrest Hall of Fame.

 

[dakor]

The late Gene Bukys chambered his barrels using exactly the same method. Heck, all he ever did was win a a World Championship, the Supershoot, and shoot his way in to the Benchrest Hall of Fame.

Look up Bob Pastor aka "The Viper" and his shooting achievements. Then take a look at the F Class rests and other things he made. Top Notch shooter and Machinist.

Plus the box of Voodoo chicken bones to rub on the barrel when you are done to make it shoot are on another level.

So keep on chambering the way you like, pre boring is about like climate change its a cult. You are either in or out of that cult and no matter what amount of facts or other processes that are presented to the person in said cult its always going to be if you are not doing it this way you are doing it wrong.

So when I use the process I use and even my sporter weight hunting rifles are consistently printing well under half MOA at 100 yards, 500 yards and so on I am going to stick with said process.

The most important part that validates what I am doing is 95 percent of my customers are repeat customers, I build rifles for guys that compete some who even belong to this site and others that just shoot/hunt again some that are on this site.

 

[LVLAaron]

So, you learned one way, only do it one way, tell everyone else they're wrong, and insist the other guys are in a cult? lol. k.

 

[urbanrifleman]

So, you learned one way, only do it one way, tell everyone else they're wrong, and insist the other guys are in a cult? lol. k.

I'm not sure which person you are talking about, because it seems to fit a lot of people.

 

[dakor]

I'm not sure which person you are talking about, because it seems to fit a lot of people.

Not correct, I have pre bored before as a test. I found no benefit to it at all other than like Dusty mentioned increasing the chance of making a mistake. That with the fact you are making a lot of assumptions about the bore that you cannot prove but feel you have to correct it.

Than add in the fact that I have spoken with about a dozen or so smiths who use the pre bore process when I was looking at going that route and everyone of them has said in the conversation it saves on reamer wear.

One of those is a popular one on this very site.

I do my research and try things before I make a decision or have an opinion.

That's why I posted in the first place it was said in here that pre boring is the most accurate way to cut a chamber and that is not correct. Like I said before you want to pre bore by all means pre bore but do not say its the most accurate way to do something because its not.

I know guys that cut chambers between centers that have good results. Hell I even met a guy that worked for a big arms company that when they chamber their 50 cal bmg's they are between centers and when the reamer engages they open the steady rest and let the reamer float the bore. Their rifles shoot so what does that tell you?

 

[butchlambert]

Not correct, I have pre bored before as a test. I found no benefit to it at all other than like Dusty mentioned increasing the chance of making a mistake. That with the fact you are making a lot of assumptions about the bore that you cannot prove but feel you have to correct it.

Than add in the fact that I have spoken with about a dozen or so smiths who use the pre bore process when I was looking at going that route and everyone of them has said in the conversation it saves on reamer wear.

One of those is a popular one on this very site.

I do my research and try things before I make a decision or have an opinion.

That's why I posted in the first place it was said in here that pre boring is the most accurate way to cut a chamber and that is not correct. Like I said before you want to pre bore by all means pre bore but do not say its the most accurate way to do something because its not.

I know guys that cut chambers between centers that have good results. Hell I even met a guy that worked for a big arms company that when they chamber their 50 cal bmg's they are between centers and when the reamer engages they open the steady rest and let the reamer float the bore. Their rifles shoot so what does that tell you?

Not much Sir!

 

[urbanrifleman]

Not correct, I have pre bored before as a test. I found no benefit to it at all other than like Dusty mentioned increasing the chance of making a mistake. That with the fact you are making a lot of assumptions about the bore that you cannot prove but feel you have to correct it.

Than add in the fact that I have spoken with about a dozen or so smiths who use the pre bore process when I was looking at going that route and everyone of them has said in the conversation it saves on reamer wear.

One of those is a popular one on this very site.

I do my research and try things before I make a decision or have an opinion.

That's why I posted in the first place it was said in here that pre boring is the most accurate way to cut a chamber and that is not correct. Like I said before you want to pre bore by all means pre bore but do not say its the most accurate way to do something because its not.

I know guys that cut chambers between centers that have good results. Hell I even met a guy that worked for a big arms company that when they chamber their 50 cal bmg's they are between centers and when the reamer engages they open the steady rest and let the reamer float the bore. Their rifles shoot so what does that tell you?

Oh I think you are directing your comments at the wrong guy. I believe there are lots of ways to chamber. I'm not in a cult.

 

[LVLAaron]

Not correct, I have pre bored before as a test. I found no benefit to it at all other than like Dusty mentioned increasing the chance of making a mistake. That with the fact you are making a lot of assumptions about the bore that you cannot prove but feel you have to correct it.

Than add in the fact that I have spoken with about a dozen or so smiths who use the pre bore process when I was looking at going that route and everyone of them has said in the conversation it saves on reamer wear.

One of those is a popular one on this very site.

I do my research and try things before I make a decision or have an opinion.

That's why I posted in the first place it was said in here that pre boring is the most accurate way to cut a chamber and that is not correct. Like I said before you want to pre bore by all means pre bore but do not say its the most accurate way to do something because its not.

I know guys that cut chambers between centers that have good results. Hell I even met a guy that worked for a big arms company that when they chamber their 50 cal bmg's they are between centers and when the reamer engages they open the steady rest and let the reamer float the bore. Their rifles shoot so what does that tell you?

I think we all stopped listening when you said we can't bore a straight hole.

 

[Cloudrepair]

Not correct, I have pre bored before as a test. I found no benefit to it at all other than like Dusty mentioned increasing the chance of making a mistake. That with the fact you are making a lot of assumptions about the bore that you cannot prove but feel you have to correct it.

Than add in the fact that I have spoken with about a dozen or so smiths who use the pre bore process when I was looking at going that route and everyone of them has said in the conversation it saves on reamer wear.

One of those is a popular one on this very site.

I do my research and try things before I make a decision or have an opinion.

That's why I posted in the first place it was said in here that pre boring is the most accurate way to cut a chamber and that is not correct. Like I said before you want to pre bore by all means pre bore but do not say its the most accurate way to do something because its not.

I know guys that cut chambers between centers that have good results. Hell I even met a guy that worked for a big arms company that when they chamber their 50 cal bmg's they are between centers and when the reamer engages they open the steady rest and let the reamer float the bore. Their rifles shoot so what does that tell you?

When you pre bored for your test did you dial in the breach and throat or the muzzle and throat ?

 

[Edd]

Some people focus on how close to perfect their work can be. Others focus on how far from perfect is good enough.

This applies to many types of work, not just chambering barrels, and will never change.

 

[Greg Y]

You can skin a cat with a knife, air compressor, torch.....

Pre drilling followed by single pointing assuming your system of zero indication is satisfactory and no additional stress is induced has no real potential to induce deviation.

A ream started perfectly into the bore in the above barrel without any material removal will simply follow the path of least resistance.

We discussed earlier in this thread the importance of the drill being ground on center.....because it will deviate. (Hence the single point to clean it up) If your ream is ground perfectly and you induce no flex, have no chip weld, have a square push, sharp tool and good luck.....you should have great results too.

The idea of bashing a pre bored hole is mind blowing to me. Drill a half inch hole and look at the size of chip it pulls. Look at the chip migration...it's a huge chip that flows well.

Now do the same with a chamber reamer.....chip load gets critical in no time.

Drills are cheap and easily re ground.....reamers, not so much.

There's just a zillion reasons why it makes sense.

The fixturing to me is simple, you either do it to indication or you just jump right to centers and save the time.

 

[dakor]

Some people focus on how close to perfect their work can be. Others focus on how far from perfect is good enough.

This applies to many types of work, not just chambering barrels, and will never change.

Not sure who that is directed to but if its to me you are very wrong.

 

[boltfluter]

I have discussed this very topic with a couple machinists one who works on some high level parts.

Both agreed the process is flawed and a waste of time. If you want to pre bore by all means pre bore do what works for you.

If it was the end all be all method why are not all rifle builders using it?

There are many many smiths that are not doing it and their rifles are winning matches.

With the results I see with my rifles on paper I will just stick with running the reamer start to finish.

By design, a reamer is designed to finish a hole, not drill one! This is the most basic of machine shop knowledge, as in machining 101. You need to find some smarter friends. Lol!
Paul

 

[Cloudrepair]

When you pre bored for your test did you dial in the breach and throat or the muzzle and throat ?

I asked this question for a good reason.
Your machinist friend must have known how you dial in your barrel's because that is the only reason I believe he would say that because it wouldn't make a difference if you dial in the throat and the breach.
Other then saving the reamer
If you trested the drill and bore method only dialing in the breach and throat then you wouldn't see the difference.
Now do one with the throat and muzzle without drilling and bore method and see what happens

 

[Lucky Shooter]

I use the much discussed method of drill, taper bore etc because
I'm confident and comfortable with it. This yields good results considering my skill levels and machine quality. I don't pretend to think this is the best method for all----you play your game and I'll
play mine. BTW, I don't oppose learning improved methods.

@butchlambert has raised the question----why use a pilot bushing
if you taper bore ? Somehow I picked up early on that the bushing
helped support the skinny end of the reamer.

I'd appreciate any in-depth comments about the use of a bushing.

A. Weldy