Help wanted from 45 2.1 about chamber/throat specs

[Ajax]

I have a new 2 groove 1943 dated 1903A3 barrel and i am wondering about the throat specs for using cast only and how do i figure the dimensions out. Your help will be greatly appreciated.

Andy

[45 2.1]

Are you going to barrel it as is or are you going to set it back slightly and re-chamber it? Two grooves can shoot very well as is without any work other than indexing/headspacing it correctly...... provided it is put together correctly. The NRA compiled a book involving all their articles and this book is on castpics. It has a full page table showing what boolit types that work in various rifling types (2, 4, 5, 6 etc groove rifles). A two groove likes the short body long nose type. Boolit body/nose size basically determines what you'll get in these.

You have the opportunity here to set the barrel back and put a match grade 308 chamber especially for cast in this. The two groove barrels are usually of excellent quality to warrant this.

Whether you choose the 308 or 30-06, you will need to pick what boolit you will be using. The 311299, 314299 or an equally suitable boolit would be good..... as long as it is not undersize to the barrel/throat dimensions used.

[Ajax]

It is only short chambered right now so it will need cut and head spaced. i want to go with the 30-06. I will look that book up and read it thank you for the information. After i read it i will come back and ask more educated questions. thank you .

Andy

[45 2.1]

You need to measure the chambers case neck diameter also. Even if short chambered, it could cause problems. An impact lead throat slug with the case shortened enough to extrude lead in front of the case would do fine, plus give you what was there for a throat now.

[Ajax]

It hasn't been chambered at all.



Andy

[45 2.1]

I've never seen one with no chamber cut before, but that is probably a good thing for you.
Here are the things you need to do:

1. Measure your supply of 30-06 case necks for wall thickness (a tubing mic works
well for that)
2. Decide what boolit you want to shoot, (it helps to have one that is 0.311 or just
slightly bigger on the bands).
3. Measure the body length of that boolit, its band diameter, the nose diameter and
the length of the parallel sided nose on it before it starts curving toward the meplat.
4. You need the land diameter (bore) of your barrel. You need that for the reamer
specs anyway.

Once you have those things we can start.

[Ajax]

sorry it is cut it needs finish reamed.
I will get the measurements for you.

Andy

[Ajax]

As far as molds go would this be a good one?

http://accuratemolds.com/bullet_detail.php?bullet=31-200L-D.png

Andy

[45 2.1]

As far as molds go would this be a good one?

http://accuratemolds.com/bullet_detail.php?bullet=31-200L-D.png

Andy

That depends entirely on whether or not the bore ride nose fits what you have. A short chambered barrel already forces you to follow what was laid out with little variance except for the leade. The few choices you have are to taper the throat if it is too small or match what is there if too large or set it back and fix everything. You need to check what you have... load some dummy cartridges up with boolits you have, magic marker the neck and boolit up and thumb seat it as much as possible to see whats there OR do a lead impact slug.

[Ajax]

I will when i have the barrel installed and decide on a finish reamer.


Andy