Pre-bore and pusher.

C

Curious

New member
Ive read a couple of comments on forums from guys who ditch the pilot bushing while using this method and they are getting good results, the idea seems to be to stop the pilot from influencing the reamed as it follows the pre-bore and they also dislike the idea of the bush rubbing up the rifling right where the bullet will touch.

Can anyone speak from first hand experience of this?
 
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I've done it several times on long cases where the bore is crooked enough that the spot where the pilot will end up runs true but the part where it first enters the rifiling has some run out and I get good results. Sometimes I ream to almost full depth and then put the pilot on.
 
ndh78 said:
I've done it several times on long cases where the bore is crooked enough that the spot where the pilot will end up runs true but the part where it first enters the rifiling has some run out and I get good results. Sometimes I ream to almost full depth and then put the pilot on.
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Thats interesting, thanks.

When you say good results, do you measure these and if so how good is good?
 
If you use an accurate dial indicator like an Interapid and a stylus long enough to reach the point in the to-be cut chamber where the bullet will intersect the bore and closely dial in that part, and you prebore the chamber base taking all the curvature out at that point, then use a floating pusher and a snug fitting pilot you will end up with an accurate and to proper size chamber.


,
 
JerrySharrett said:
If you use an accurate dial indicator like an Interapid and a stylus long enough to reach the point in the to-be cut chamber where the bullet will intersect the bore and closely dial in that part, and you prebore the chamber base taking all the curvature out at that point, then use a floating pusher and a snug fitting pilot you will end up with an accurate and to proper size chamber.


,
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Well said and very true. :)
 
JerrySharrett said:
If you use an accurate dial indicator like an Interapid and a stylus long enough to reach the point in the to-be cut chamber where the bullet will intersect the bore and closely dial in that part, and you prebore the chamber base taking all the curvature out at that point, then use a floating pusher and a snug fitting pilot you will end up with an accurate and to proper size chamber.
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My question was regarding any advantages or disadvantages in ditching the pilot bush Jerry, have you ever tried this method?
 
Curious said:
My question was regarding any advantages or disadvantages in ditching the pilot bush Jerry, have you ever tried this method?
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If the barrel is a 5C type barrel, it's pretty important to use a fairly tight bushing. Something to do with the canted land will sometimes try to induce chatter if the pilot doesn't fit well. I'll go along with what Jerry states. It's worked well for me a long time. Been using basically the same system for chambering barrels since 1991. Tried all the other methods, but always come back to an indicated bore at the throat and boring the body to rough out the chamber.
 
Butch Lambert said:
Bill, I think he has been directed there earlier. He wants you to school him first hand! Possibly can't comprehend the links.
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Wow, I guess forum spirit is dead among some then?

Take some time to think about this Butch.

A guy puts a random compilation of thoughts about chambering into a document and then guys like you just link newbies like me to it because you can't be arsed to talk it through again, your not interested in a way that I get the answer Im looking for in a more direct and efficient manner, you call it 'first hand schooling', I call it being helpful. If you can't be bothered to engage with me then why say anything at all, just let it slide by?

Steering me to a document that Ive looked at a few times is pointless, if I had got the information I wanted in a way I understood then I would not have been asking the question. There may be lots of great info in that compilation but seriously, have you tried reading through it all from the perspective of a novice? - I will assume no is your answer! If your stale in terms of forum contributions the why be a smart arse and spoil it for me? Forums are about sharing information in many different ways, directing to stickies every time is just plain lazy and counter-productive so I end up frustrated and I walk away.

You win big guy.
 
Curious said:
My question was regarding any advantages or disadvantages in ditching the pilot bush Jerry, have you ever tried this method?
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I wonder? Why "try" a chamber without using a pilot bushing when I have one available? At best it might give a good chamber but also it might not??? If you use a snug fitting pilot on the reamer the merge point at the freebore and leade will create the best fit and that is what the bullet needs to start its journey down the barrel without any in-bore yaw.

.
 
Curious said:
Ive read a couple of comments on forums from guys who ditch the pilot bushing while using this method and they are getting good results, the idea seems to be to stop the pilot from influencing the reamed as it follows the pre-bore and they also dislike the idea of the bush rubbing up the rifling right where the bullet will touch.

Can anyone speak from first hand experience of this?
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The pilot bushing can't follow the prebored hole. If you indicate in the throat area, as I do and use a floating pusher, I want the reamer aligned as quickly as possible, that means using a bushing. I use flush coolant and have never had an issue with marring the finish on the lands.
 
Curious said:
Wow, I guess forum spirit is dead among some then?

Take some time to think about this Butch.

A guy puts a random compilation of thoughts about chambering into a document and then guys like you just link newbies like me to it because you can't be arsed to talk it through again, your not interested in a way that I get the answer Im looking for in a more direct and efficient manner, you call it 'first hand schooling', I call it being helpful. If you can't be bothered to engage with me then why say anything at all, just let it slide by?

Steering me to a document that Ive looked at a few times is pointless, if I had got the information I wanted in a way I understood then I would not have been asking the question. There may be lots of great info in that compilation but seriously, have you tried reading through it all from the perspective of a novice? - I will assume no is your answer! If your stale in terms of forum contributions the why be a smart arse and spoil it for me? Forums are about sharing information in many different ways, directing to stickies every time is just plain lazy and counter-productive so I end up frustrated and I walk away.

You win big guy.
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You type a lot, but haven't said anything. Didn't mean to piss in your Post Toasties.
 
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Curious said:
There may be lots of great info in that compilation but seriously, have you tried reading through it all from the perspective of a novice? - I will assume no is your answer! If your stale in terms of forum contributions the why be a smart arse and spoil it for me? Forums are about sharing information in many different ways, directing to stickies every time is just plain lazy and counter-productive so I end up frustrated and I walk away..
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Here is a response from a novice.

Besides the tremendous help I got from Butch, I printed and put that compilation in a binder and read it I don't remember how many times, I even took it with everywhere I went and read it any chance I had; in flight, at the airport, break time from the grandkids, at the hotel after shooting in matches, etc. It was overwhelming at first, I am kind of slow, but what was written in the whole binder made more sense later the more I read it. I tried the different approaches others wrote about, turned a bunch of shot out barrels into buckets of chips. Lots of good information, but after testing other procedures, I found out my lathe, my cutters, and my set up are not the same as anyone else's, I better learn how to use what I have to achieve the same results. I suppose I was not afraid to try and fail and just dove right into it, and learned a lot, and still learning. Now, even after cranking over a couple of dozen barrels I still consider my skills to be in the crawl phase compared to the gentlemen on this forum.

I don't know what machining background you have, I started from nothing, l had to learn the very basics of running a lathe and a mill. I spent many hours sometimes almost all night trying different things. Ignorance is bliss.

It is a journey, enjoy the ride.
 
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You asked Butch for anything you might read on the subject. I had no indication you had read the sticky I referenced or that you had been directed there before. That document contains a lot of good information. I see nothing wrong with directing someone to a sticky (that's why it's there). Maybe if you had noted you had read the document and had questions others might find time to discuss your questions.

You might feel the forum participation is somewhat dead which may be true. You have to understand that after many many years of these very questions followed by some of the heated bickering that ensues has taken a bit of the motivation to share out of quite a few.

As to your question: I basically do what Tooley and Sharrett have stated although I doubt I do what either of them do exactly. I indicate the throat, use a bushing and pre-bore. I am confident in my pre-bore method and could probably do without a bushing but I feel why do that if I have a bushing available? I feel the bushing will help to insure the throat is where it is supposed to be as the chamber is nearing completion. Inspecting with a borescope I have yet to have a misaligned throat. I have not experienced bore damage or marking of the bore from using a properly fitted pilot bushing. In the end it all comes out the way I want it so I do what works for me and not necessarily what works for others. I also try to keep an open mind and I'm certainly not above trying something new now and then.
 
Reamer flex is a real issue and I wouldn't ever ream a bored out chamber without a good fitted bushing.
Mike I have also experienced the chatter issue on a 5c or 5r barrel. I also use a snug bushing, and I use tap majic extra thick cutting oil. the Tap Magic extra thick is like glue. Its kind of a pain to clean up but it works for me. I hate 5r/ 5c barrels, and I always do my best to steer my customers away from them. The 5 grooves are also harder/ if not impossible to indicate directly off the bore like I like to do with a standard 4 groove barrel. For the life of me I have no idea why they are so popular. They are though!! Lee
 
My experience with 5R barrels is limited to Bartlein .308" and .264" 5R barrels, I have had no issues or difficulties with indicating or chambering them.
 
How many of the responders "taper bore" when they say "pre bore" ?

I see a potential issue with a taper bore and a bushing.,2 surfaces trying to guide the reamer.
 
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