OAL Gage

[Outdooroffice]

I need some help with my OAL gage. I have a Remington 700 300 win mag. I am going to start reloading once I can get the correct OAL. I can consistently measure 3.498 or 3.499. Well the Sierra manual calls for 3.340 max length. WHAT AM I DOING WRONG? I cannot get this measurement to save my life. PLEASE HELP

Thanks
Larry J

 

[wmdron]

Larry, Which OAL gauge are you using ?

 

[fredhorace77]

Im just guessing here according to what little u have wrote. Screw ur seating steam in further in ur die or turn the whole die itself in further.

If ur using the rod with a case screwed on and u put a bullet in to to measure oal in ur chamber u may be getting the distance where the bullet is engaging the rifling. Sammi specs would of course be further in than ur measurement

 

[Preacher]

Are you measuring to the tip of the bullet or to the Ogive ?
To the tip will show a lot of variables, you'll need to measure to the Ogive for the measurements you'll need..
OAL is also going to be different in each chamber, so you really need to check your particular chamber to get a exact fit for your OAL in that barrel......
The Sierra manual don't know your OAL is for sure, so you need to find out for yourself..

 

[fdshuster]

Larry: The Sierra manual, and all others, state the over-all-length of the loaded round as a reference only.
That was the O.A.L. of the round(s) that were tested, and they determined that the load used is safe when loaded to that length.

If the round is seated shorter or longer, pressures could increase, and that's what you are responsible for determining. One of the reasons why we are told to start "low" and carefully work our way up, when increasing powder charges.

Use the Hornady chamber O.A.L. gauge, find the measurement from the case head to the bullet ogive with the bullet touching the lands, then seat them to whatever length you want. I personnally start off with a jump of .020", then will try .010" and finally just touching. And, of course, when doing this I'm looking for the smallest group sizes, further adjusting as necessary.

 

[Outdooroffice]

I am using the Hornady OAL gage with the 30 cal. case and 180 gr Serria BTHP. I think I may be having some issues with Lawyer safe chambers and not match grade barrel made just for my caliber.

Fdshuster - the jump you speak of at .020, would it be best if I start at the .070 or .050 mark and go from there since I am using a factory barrel.

Thanks for all the help

 

[fredhorace77]

its actually got nothing to do with so called lawyer safe chambers (there is no such thing)...all factory chambers are made to sammi specs...all loads listed in a manual use sammi specs. on their demisions...

and as far as where to start...start your bullet at the sammi spec demision and then move it out .010 at a time while looking for accuracy..eventually if you keep moving it out it will contact the rifiling

 

[fdshuster]

fred: While I agree with most of what you said, the freebore dimension is not subject to SAAMI specs. The manufacturer can make it any length they want.

An example would be the Savage rifles chambered in 6BR. If you choose a slow twist barrel ( 1-12?) you "should" get a relatively short throat for the short, lightweight bullets.

If you want the faster 8 twist, then you can expect the throat to be longer to accomidate the 105 to 108 ( and in some cases, even heavier/ longer) bullets.

Of course there have been times when someone got a slow twist barrel with a really long throat, or vice versa.

The reason I spec my own chambering reamers, cut to the dimensions I want, but with a factory rifle you do not have that option.

Larry: I would suggest you get your bullet seating depth established, in relation to the contact point in the leade/throat and write that length down for future reference. Seated to touch may leave you with the bullet just barely contacting the case neck, or even falling out, if it's a really deep throat. If that happens then you will have to jump the bullets, you have no other choice. The good news is a lot of rifles and cartridges are not critical on seating depth & may do very well with even a lot of jump.

And in my previous post I forgot to add: The cartridge over-all-length that is given in the loading manuals is the length that was used when they established the feet per second velocity and c.u.p. numbers. Change the seating depth & those f.p.s. & c.u.p. numbers would be invalid.

 

[rocketron]

one thing no one talked about is if your feeding it from a magazine.

seated to touch the lands may be to long to feed from one.

 

[Outdooroffice]

I will be shooting one at a time. I am going to start my OAL at 3.325 and go from there. Should I increase at .005 or .010? Also how many rds/groups should I shoot of each measurement?
Thanks
Larry J