Trimming question

[Texas Solo]

Simple question...why?
I got the tool from Sinclair to measure my chamber for this purpose. Chamber measures 2.045 from bolt face to what I'll call the "brass stop" point. That's the point in chamber where the case mouth reaches as far as it's going to go.

So, given that dimension of 2.045", why would it be desirable to trim to 2.005? After initial trimming to 2.005", my twice fired brass measures 2.015 after FL sizing. Seems to me that making it shorter would only lead to a carbon ring.

What am I missing here?

 

[stool]

not a thing...
you are correct....
trim to your chamber and do not look back..just mark them well for which rifle and what length.
if you trim every time...you can trim real close and make the possibility of a carbon ring almost not possible..

 

[Martin52]

Is this a factory or custom set up ?

Martin

 

[Texas Solo]

Is this a factory or custom set up ?

Martin

Savage #12 with Shilen Select match 1/10 26" 308 Standard 308Win chamber

 

[Martin52]

OK, on that basis I would let them grow but no longer than 2.025/2.030 to leave adequate clearance, but not too much clearance that would otherwise assist a carbon ring forming.

It is longer than I would have thought but my own experience with custom actions indicates 2.020/2.025 and trim length 2.005/2.010

Martin

 

[fguffey]

So, given that dimension of 2.045", why would it be desirable to trim to 2.005?

It is not desirable, I want my cases to cover the chamber, problem, no one knows the length of the chamber "from bolt face to what I'll call the "brass stop" point. there is no reason for not knowing. Same for deterring the length of the chamber from the shoulder to the bolt face, no excuse. A reloader that is familiar with case forming, their press, different dies and shell holder can form cases to determine the length of the chamber "from bolt face to what I'll call the "brass stop" point".

Then there are chambers that are long from the shoulder to the bolt face, I have one chamber that is field reject length +.002", when forming cases for that chamber I add .016" between the shoulder to the head of the case, To keep up with covering my chamber with the case I add .014" to the length of the case "from bolt face to what I'll call the "brass stop" point".

F. Guffey

 

[Texas Solo]

So, given that dimension of 2.045", why would it be desirable to trim to 2.005?

1) It is not desirable
2) no one knows the length of the chamber "from bolt face to what I'll call the "brass stop" point.
3) there is no reason for not knowing.

F. Guffey

So far, we all seem to agree that trimming to the factory spec is not always best.

Mr Guffey....I agree with #1 & #3 above, but don't understand your #2. I certainly do know my spec, which is what brought up this topic to begin with. Or did you mean to say that most people don't know or care to look?

 

[fguffey]

Or did you mean to say that most people don't know or care to look?

Two out of three is not bad, forgive, don't know are care? My opinion, it is about 'how', the standard answer is 'do a chamber cast'. Trimming a case to length is conditioning/automatic. I have built wildcats, in the process the case shortened from the mouth of the case to the case head .045", others .035". Some wildcats have short necks, when forming the cases the case got longer from the shoulder to the head of the case meaning the loss in length was in the neck. Most settle for short cases, I used longer cases, for wildcat chambers based on the 30/06 I use 280 Remington cases. The 280 Remington case is longer than the 30/06 by .051". The extra length comes in handy when a 30 Gibbs chamber is used. The neck is .217" long. Some believe the 300 Win Mag has a short neck, the neck on the 300 Win Mag is about .265" long.

Many reloaders trim the length of the case with total disregard for the length of the chamber from the shoulder to the head of the case. The Wilson case gage measures from the datum to the case head and from the datum to the mouth of the case.

F. Guffey

 

[Texas Solo]

Thanks for that clarification. Now I get your point.

 

[artbosco]

Simple question...why?
I got the tool from Sinclair to measure my chamber for this purpose. Chamber measures 2.045 from bolt face to what I'll call the "brass stop" point. That's the point in chamber where the case mouth reaches as far as it's going to go.

So, given that dimension of 2.045", why would it be desirable to trim to 2.005? After initial trimming to 2.005", my twice fired brass measures 2.015 after FL sizing. Seems to me that making it shorter would only lead to a carbon ring.

What am I missing here?

Trim brass 10/1,000ths [.010"] off the chamber length for safety, and another 10/1,000ths [.010"] for growth.

What does your reamer's dimensions drawing tell you the about the length of the chamber? You do have a drawing, right?

 

[stool]

no way....
that leaves 15 thou to start a ring..that is factory spec clearance...not custom at all.
trim every time and go real long....avoid carbon build up.
i would do .007 -.005.....you have to trim every time and keep an eye on single shot growth.

OK, on that basis I would let them grow but no longer than 2.025/2.030 to leave adequate clearance, but not too much clearance that would otherwise assist a carbon ring forming.

It is longer than I would have thought but my own experience with custom actions indicates 2.020/2.025 and trim length 2.005/2.010

Martin

 

[stool]

do not go off the PRINT go off the actual CHAMBER.
.020 is silly in a custom bbl with handloaded ammo....
trim every time, log actual growth per shot...

Simple question...why?
I got the tool from Sinclair to measure my chamber for this purpose. Chamber measures 2.045 from bolt face to what I'll call the "brass stop" point. That's the point in chamber where the case mouth reaches as far as it's going to go.

So, given that dimension of 2.045", why would it be desirable to trim to 2.005? After initial trimming to 2.005", my twice fired brass measures 2.015 after FL sizing. Seems to me that making it shorter would only lead to a carbon ring.

What am I missing here?

Trim brass 10/1,000ths [.010"] off the chamber length for safety, and another 10/1,000ths [.010"] for growth.

What does your reamer's dimensions drawing tell you the about the length of the chamber? You do have a drawing, right?

 

[Ackman]

Simple question...why?
I got the tool from Sinclair to measure my chamber for this purpose. Chamber measures 2.045 from bolt face to what I'll call the "brass stop" point. That's the point in chamber where the case mouth reaches as far as it's going to go.

So, given that dimension of 2.045", why would it be desirable to trim to 2.005? After initial trimming to 2.005", my twice fired brass measures 2.015 after FL sizing. Seems to me that making it shorter would only lead to a carbon ring.

What am I missing here?

You're not missing anything. With saami chambers it's not desirable. People trim needlessly because they don't know any better, and read too much stuff written by others who don't know any better.