Running a Reamer in deep

[swd]

If your chamber is .100” longer than a BR go gage the FB has me moved that same amount.

 

[tom]

Everybody is right! But technically Dusty is more righter, lol. The free bore section is indexed off the end of the neck cut, so it would end up a .104" free bore, long necked(chamber neck), but the brass will still be around the same length, 22 brx. The touch point for the bullet would in fact be .100" further away from the bolt face however. But the bullet base would still sit properly if it was to begin with as a 22 br.


Tom

 

[Dusty Stevens]

If your chamber is .100” longer than a BR go gage the FB has me moved that same amount.

And so has the shoulder, neck and fb- therefore the fb is exactly the same, since it stayed at the same point in front of the case mouth. The reamer hasnt changed but the shoulder is farther from the boltface and the case is larger at the base.

 

[swd]

The effective free bore that the cartridge case see’s is longer if run the reamer in long and to me that’s where the rubber meets the road.

If you need say a zero FB chamber and you run in a zero FB reamer in an extra .100” farther down well sure it’s still zero to the chamber but that doesn’t do you any good if you actually need a normal zero FB chamber.

The next time a customer needs a zero zero FB chamber and your only reamer is a .104” just run in a neck reamer in an extra .104” after you cut the chamber and tell him it’s zero FB and see how that works out. Same way of thinking in my opinion.

 

[Dusty Stevens]

The next time a customer needs a zero zero FB chamber and your only reamer is a .104” just run in a neck reamer in an extra .104” after you cut the chamber and tell him it’s zero FB and see how that works out. Same way of thinking in my opinion.

We didnt say anything about neck reamers. Sure i can make the neck longer and fb shorter with that. I can also extend the fb with a throating reamer. Here is what you were saying at first- if i run this reamer in .100 deeper would you agree the fb is exactly the same? Would you agree the case neck is exactly the same length? Would you agree the body will be .100 longer and larger at the base according to case taper?

 

[xswanted]

I think I’ll just do a 22 Dasher. That sounds easier.

 

[swd]

All the cartridge cares is where the bullet sits in the case in relation to where the bullet can touch the lands. If you run the reamer in .100” deeper the bullet sits .100” farther out of the case (if it can) to get to the lands.

What your saying is yes you have artificially kept the same free bore.
BUT in reality the gun now sees a longer free bore after tuning it in long.

 

[Bamban]

SWD,

Please educate this newbie. I have a reamer that has 0.100 freebore. If I were to run the reamer + 0.100, are you telling me my freebore is now 0.200? Where is the end of the neck after running the reamer +0.100?

 

[Dusty Stevens]

SWD,

Please educate this newbie. I have a reamer that has 0.100 freebore. If I were to run the reamer + 0.100, are you telling me my freebore is now 0.200? Where is the end of the neck after running the reamer +0.100?

Exactly what hes saying.
In my world Bullet still touches the lands with the base in exactly the same point in the neck. Freebore is the same, but yes the bullet is .100 farther from the boltface- but thats not freebore

 

[swd]

I guess you have to ask yourself what the purpose of free bore is and why it is or isn’t there and how you want to define it.

 

[hoz53]

All the cartridge cares is where the bullet sits in the case in relation to where the bullet can touch the lands. If you run the reamer in .100” deeper the bullet sits .100” farther out of the case (if it can) to get to the lands.

What your saying is yes you have artificially kept the same free bore.
BUT in reality the gun now sees a longer free bore after tuning it in long.

But wouldn’t that be the first time you fire the case and then it would form itself to the chamber and you would have FB same as reamer? Wouldn’t the shoulder of the unfired case be .100 away from the chamber shoulder?

 

[Dusty Stevens]

The Effective free bore the cartridge sees has changed. But I’m all done explaining this. Do it however you please.

How has the freebore changed is what we’re asking? Im just trying to understand. The freebore is at a farther point from the boltface but freebore is measured from the case mouth so effectively its still the same.

 

[Dusty Stevens]

But wouldn’t that be the first time you fire the case and then it would form itself to the chamber and you would have FB same as reamer? Wouldn’t the shoulder of the unfired case be .100 away from the chamber shoulder?

Yes

 

[hoz53]

Yes

That’s what I thought and it seems like brass wouldn’t last long blowing it out that far.

 

[holstil]

Wouldn't matter if you ran the reamer in 3"
The free bore remains the same relative to the neck. Your just making a longer chamber, base to shoulder.
I think the confusion is steming from the parent brass not reaching the new neck line. You would need to form the brass from a longer parent to maintain the new neck length.
In essence cutting a longer chamber using same brass will lengthen the distance the bullet needs to extend from brass to touch lands, but that's because the brass is now too short. Is why a dasher has .100 shorter neck but .100 longer shoulder from base. The total length of brass is same.
Your both right!

 

[DaveTooley]

you know I respect you about as much as anybody but im having a hard time seeing what yall are seeing here. if what you say is true then that means the case mouth stops moving forward, the fb does keep moving forward along with the body and shoulder. so everybody that has posted here has reamers stopping certain points but other points moving forward. ive drawn a diagram and everything and I just cant see how a case mouth stops but the shoulder keeps going.

Dusty
I think we're talking chamber length vs cartridge case length. Chamber(shoulder and throat) moves forward but the case mouth stays at the same location for a given base cartridge.

 

[Dusty Stevens]

Dusty
I think we're talking chamber length vs cartridge case length. Chamber(shoulder and throat) moves forward but the case mouth stays at the same location for a given base cartridge.

But if you take a 6br reamer, run it in an extra .100 the case mouth moves forward as well. Not talking about a brx reamer where the mouth would stay but shoulder move forward, the br reamer would keep the same neck

 

[DaveTooley]

You're correct the chamber does move forward. I never said it didn't.
I always thought case and cartridge meant the same thing. The chamber is the chamber not a "case".