250 Savage headspace gauge?

[ronniet]

I am working on a 250 savage checking the chamber, and I have a Forster Go gauge. It closes fine on the go gauge, and I was wondering how much longer a NO Go or a Field Gauge is than the Go? can adhesive tape be added to the end of the GO gauge to these lengths?
What it is with properly trimmed and resized brass the bolt is not wanting to close.
So I pulled the 100 gr. bullets from the dummies I was using, resized and checked 5 of them again and they went.
I then loaded one of the 100 gr. bullets to COAL again and the bolt failed to close, I then coated the bullet with Dykem and checked it and it seems there is no Free Bore at all, rifling starts at the case neck. Is it possible that somoni used a reamer that had no free bore? Rifle appears unfired.
Ron

[M-Tecs]

You can purchase reamers with no lead. These are used when you use a separate throat/lead reamer. http://pacifictoolandgauge.com/311-throat-and-neck-reamers

Min. headspace is 1.5792" and Max is 1.5892" https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

[ronniet]

You can purchase reamers with no lead. These are used when you use a separate throat/lead reamer. http://pacifictoolandgauge.com/311-throat-and-neck-reamers

Min. headspace is 1.5792" and Max is 1.5892" https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

that is .010 difference is that on the field gauge? I ran an endoscope into the chamber and it appears the rifling is right up to the front edge of the neck, I wonder what length of free bore should it have?
Ron

[Texas by God]

What kind of rifle? A paraffin chamber cast is easy to do to get a look at what's up. The .250 and it's little brother 22-250 have provided a lot of venison for my family. Great cartridge.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[M-Tecs]

that is .010 difference is that on the field gauge? I ran an endoscope into the chamber and it appears the rifling is right up to the front edge of the neck, I wonder what length of free bore should it have?
Ron

The free bore is in the SAAMI data page 77. https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

This is based on memory but the field gauge is max and the no go is .003" under so the go is .0" the no go is plus .007" and the filed is plus .010"

[ronniet]

Thank you M-Tecs I am getting .105 free bore from that SAAMI page is that correct?
Texas By God the rifle is a built '36 Mexican 98

[EDG]

The .105 is not a true parallel freebore.
Rather it is a tapered cone machined from .261 diameter to the .250 bore diameter.
More than half of the taper is the 3 degrees per side that cuts the .250 bore to the .257 groove diameter.
The 3 degree slope that over the leade angle on the rifling is .067 long. That is from the .257 dia to the .250 diameter
The 3 degree slope from .261 down to the .257 diameter is only .038 long.

So there is really almost no free bore there is only a tapered leade into the rifling.

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf


Thank you M-Tecs I am getting .105 free bore from that SAAMI page is that correct?
Texas By God the rifle is a built '36 Mexican 98

[ronniet]

The .105 is not a true parallel freebore.
Rather it is a tapered cone machined from .261 diameter to the .250 bore diameter.
More than half of the taper is the 3 degrees per side that cuts the .250 bore to the .257 groove diameter.
The 3 degree slope that over the leade angle on the rifling is .067 long. That is from the .257 dia to the .250 diameter
The 3 degree slope from .261 down to the .257 diameter is only .038 long.

So there is really almost no free bore there is only a tapered leade into the rifling.

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

I saw where the free bore was tapered at 3 degrees but had never seen one that was tapered, I did get the figure that it was .105 long from the drawing but I don't get the angle lengths that you stated just from this drawing?
The reamer that I was loaned to cut the free bore is a hand made reamer and although it was said it was for cutting the throat on a 250 it does have that taper on it, I have not used it as yet as it looked odd to me and I have yet to figure a way to
gauge how much I cut .
I will have to machine a bushing I guess that will ride against the barrel face locked with a set screw, set a known shim thickness against the front , set the screw and then remove the shim and cut till it touches the barrel and repeat?

[EDG]

The angle lengths are just the 3 degree angle as it cuts the height of the rifling from full height to zero.
You could draw it 10 times scale on quad paper or use trignometry.
Draw a right triangle laying on the long side opposite the hypotenuse. The 3 degree angle would be on your right.
The short side opposite the 3 degree angle would be on your left. The short side is (.261-.250)/2 = .0055 long. The long side is .105 long.
The depth of the rifling is (.257-.250)/2 = .0035 on each side. So you would have a smaller line opposite the 3 degree angle that represents the depth of the rifling of the bore on each side. The long leg of the smaller triangle is .067 long.
To better define it with words the start of the rifling just has a short lead in there is no free bore.
That design is very common with older designs.



I saw where the free bore was tapered at 3 degrees but had never seen one that was tapered, I did get the figure that it was .105 long from the drawing but I don't get the angle lengths that you stated just from this drawing?
The reamer that I was loaned to cut the free bore is a hand made reamer and although it was said it was for cutting the throat on a 250 it does have that taper on it, I have not used it as yet as it looked odd to me and I have yet to figure a way to
gauge how much I cut .
I will have to machine a bushing I guess that will ride against the barrel face locked with a set screw, set a known shim thickness against the front , set the screw and then remove the shim and cut till it touches the barrel and repeat?

[ronniet]

Thanks EDG you are correct, after I used the throat reamer I did a chamber cast with Cerrosafe and it was as you said, I could see it in the specs but not ever having to figure the taper and length I didn't know how, after you explained it its was all too clear.
Many thanks for your help, it turned out well.
Ron

[Deadeye Bly]

The SAMMi specs are for the 87 grain bullet the cartridge was introduced with. In a bolt action rifle where you can seat the bullet out farther and shoot 100 or 117 grain bullets you will need to throat the barrel to suit the bullet being shot. I'm a big 250 Savage fan and have several. Mine are throated to have the 100 grain bullets seated to the base of the neck. This gives additional powder capacity and lets me shoot 115 and 117 grain bullets also.

[ronniet]

Good to know, Thanks Ron