Filling the throat

[GREENCOUNTYPETE]

FILLING THE THROAT

I read about this , not something i am ready to play yet with but just for the heck of it i took a empty piece of brass and put a lubed boolit in it and seated it just far enough to get it slid in the chamber and then closed up the lever to finish seating the boolit

in did push it back into the brass , but it would seem that with the c309-170rf it doesn't touch the rifling till the crimp groove and it is .10 out of the case

and ejection is a definite issue over all length is 2.655 my rounds seated right to
the crimp groove are 2.555 these function well and are about as long as it will cycle out longer will feed from the magazine but they catch on extraction

is this an overly long chamber or is that normal.

[Baron von Trollwhack]

It doesn't matter on the question. It is impossible to answer with any certainty.

You have the rifle and it is chambered and now you know where one design of boolit touches the throat but won't work well extracting. You can obtain a few other designs and check their differences for possible use in the gun. BvT

[GREENCOUNTYPETE]

i suppose it only matters if it affects accuracy , it does make me think about trying the ranch dog design that would be interesting to try

so far it seems accurate enough with certain loads , and i have a lots of testing to do with it before i have explored this bullets possibilities with this rifle

[missionary5155]

Good morning
This much I do know with my rifles. A boolit that fills the throat will always shoot more acurately & lead less with smokeless powder without using any fillers.
All other considerations are second. If I cannot accurately hit what I am aiming at then I might as well throw rocks.
Mike in Peru

[MGySgt]

From Reading Verals book on Cast Bullet Shooting, he explains filling the Camber by shooting the bigest diameter bullet you can chamber - that way it starts straight into the lead and the rifling. (Yes all repeaters have the sam issue of COL)

If you are shooting a 30 cal and can chamber a boolit that is .312 or 313 - than use that diameter. Better seal and better accuracy.

How can you tell what the largest diameter is?

Fill a casing almost to the neck with soft lead.
Make a plug that you can then put in the casing and with the rifle pointed up (so the slug doesn't come out).
Put a rod down the barrel and use a big hammer (I use a 2 lb maul) I hammer the end of my steel rod until it quits moving.

Take round out now you have a chamber impression of your chamber. You may have to do this without the ejector as the round may be too long to come out the ejection port. If you pulled the ejector out first you can remove your bolt from the rear to get the round out.

Works for me - my 45/70 Marlins shoot .461+ boolits sub MOA with most boolits from 350 - to 460 grain.



The other way is just keep buying larger sizing dies until you get one that won't chambe and then drop back to the last one that did!

[1kshooter]

MGySgt,
would you not get the same thing by the diementions of a empty brass case that was fired in that gun with a full house load?

[MGySgt]

MGySgt,
would you not get the same thing by the diementions of a empty brass case that was fired in that gun with a full house load?

Nope - the casing springs back for easy extraction. Also you want the actual size of the chamber, throat and lead. The lead slug will give you that information.

Do you really need to do this - No -but if you want the best accuracy you can get - you do need to do something similar.

There is alway a product Cerosafe (spelling?) that you plug your bore just in front of the chamber/throat/lead then melt this stuff and pour into your chamber.

You use the largest diameter boolit you can that still alows the case to expand to release the projectile. And of course work through the action

[popper]

I did the same measurement with lasercast 170's in my 336. bullet was 0.10 longer than listed COL. Taper crimped as groove was 0.10 outside the case. Cycled fine, extracted fine. Didn't shoot too good, need .311 instead of .309. Thinking of getting some onion skin and PP these bullets.

[popper]

You can get the actual neck size by flaring an empty case incrementally until it won't chamber. You can do the same thing with the neck cut off (or a straight-waled case) to get chamber size, but that probably isn't very important.

[MGySgt]

Neck size is important - If the combination of boolit diameter and twice the case wall thickness is bigger that neck area of the chamber - it ain't gonna chamber!