Head spacing problem… 250 Savage barrel.

[hunter540]

I head spaced my 250 Savage with the Go gauge and when checked with the No Go the bolt still closed… with some resistance but not a lot.

I rechecked to see that the barrel was screwed in and snug to the Go gauge and fired some test loads to measure the brass. Un-fired cases measure 1.556" and Fired cases measure 1.563" for an overall length growth of .007". I believe that the cases are stretching too much, and the growth should be limited to .002' or .003"

So I measured my PTG gauges with my Stoney Point headspace gauge.

The PTG Go Gauge measures 1.561 and the PTG No-Go Gauge measures 1.561. One of them has to be wrong. I'm guessing that it is the Go Gauge that is wrong due to the amount of stretch when case is fired.

I looked up the SAAMI Specs online and they call for 1.572" +.0005" to the Datum line and .347" diameter at that point. I'm not getting that at all.

I've measured gauges and brass with the Stoney Point headspace gauge, No. B .350". The difference between the .347" and .350" may result in the differences in the measurements to the datum line.

So, I took an unfired case and added a piece of tape to the base (adding .002"), and I'm thinking of using that as the Go Gauge, and check the No Go length with the No Go gauge. Then re-check the stretch of the brass.

Am I on the right track?

[devildogandboy]

i had a problem with an PTG go guage before, i think it was do to quality control not paying attention. i bought it from Midway and when it arrived, it had the green stripe around it but etched on the side of it, it had no-go printed on it. Midway said they had it happen before and to return it, don't take any chances and i did return.
i buy forsters when i can now!

[airaddict]

Im sure if you call PTG they will make it right since it could be unsafe to use.....or if u have access to.someone with a lathe they could shave off a few thousands off the head of the gage to bring it to spec.

Brian

[johned]

Is there a reason you don't use a cart to set the head space?

I often see bench shooters "bumping" their bolt the last half of closing into full battery. Their brass is obviously just a few thousandths longer than the chamber. Given that head space is set by the shoulder to the base I guess that neck stuff isn't in the mix....correct? Even if they were sizing the neck less than full length, as is their practice, the brass should slip right in even if the neck wasn't re-sized and the brass wasn't reloaded. Where does the resistance come from? The brass has always been reloads that I have noticed.

Thanks,

John

[bsekf]

I always save a few fired preped brass to use as a gauge. You can move the shoulder while adjusting, so be gentle. I prefer my custom brass to a one-size- fits-all guage.

BR guys sometimes have to beat the bolt open too. They march to a little different drummer and their results show it. You can learn a great deal from their technique. However you do not want a press fit when you chamber a hunting round. BR guys don't have to worry about being charged by a irate horay marmot while reloading.

[hunter540]

The bolt resistance was from the no go gauge... I think the no go is slightly longer than the go gauge... but so slight that it I can't see the difference on my caliper, and not enough difference to stop the bolt from closing. My reloads fed fine, and fired fine. I think I have excessive headspace right now and need to tweak the barrel in a bit to eliminate some of the brass stretch. That's how I came up with the idea of using an unfired case + .002" to headspace with. I want to minimize the brass stretch to extend the reloading life of the brass. Maybe I should use the go gauge as the no go gauge.

[Blue Avenger]

I want to minimize the brass stretch to extend the reloading life of the brass. Maybe I should use the go gauge as the no go gauge.

Then take a couple of your over-sized just fired cases and full length size it in your die. Then use the case to head space for minimum growth. If you want to protect your self from pushing the soft shoulder, you could fill it with epoxy.

[hunter540]

Then take a couple of your over-sized just fired cases and full length size it in your die. Then use the case to head space for minimum growth. If you want to protect your self from pushing the soft shoulder, you could fill it with epoxy.

Good Idea! The epoxy filled case sounds a lot less flexible than a piece of tape on the base. I'll try that.

Thank you,

John

[stangfish]

I am at a loss as to what you are measuring.......or what deminsions you ar referencing. Here is a link to the SAAMI dwg of the 250 Savage.
http://www.saami.org/pubresources/cc_drawings/Rifle/250%20Savage.pdf

If your headspace is wrong and it is long it will show at the datum.... at the shoulder. Yes overall length will change but The number you quoted is not a 250 savage dimension. What tool are you using to measure the "length" with and from "Where to Where" are you measuring it.

[hunter540]

I am at a loss as to what you are measuring.......or what deminsions you ar referencing. Here is a link to the SAAMI dwg of the 250 Savage.
http://www.saami.org/pubresources/cc_drawings/Rifle/250%20Savage.pdf

If your headspace is wrong and it is long it will show at the datum.... at the shoulder. Yes overall length will change but The number you quoted is not a 250 savage dimension. What tool are you using to measure the "length" with and from "Where to Where" are you measuring it.

I googled the SAAMI Specs and my reference (p.159) shows 1.5792+.0005 and .347" diameter. Your reference top diagram shows 1.5792-.007 and .347" diameter. The bottom diagram shows X 1.5892 Max and 1.5792 Minimum. I don't know why there is a difference… but I'll swap out my reference for yours. Both refer to the datum line about halfway down the slope of the shoulder. Both reference 1.5792" as minimum.

I used the Stoney Point (Now Hornaday) gauge No. B .350" listed as the correct one for the 250 Savage.
I didn't measure to verify the opening in the gauge itself… but it should be close enough for comparisons.
This will read from the base of the brass to the datum line on the shoulder.

http://www.cabelas.com/tools-accessories-hornady-lnl-headspace-kit-body-1.shtml?WT.tsrc=CSE&WT.mc_id=bingcashback&WT.z_mc_id1=740263&rid=40&mr:referralID=41179de6-c435-11e1-ac63-001b2166c2c0

[barthowes]

did you first measure the hornady comparitor with bushing, then set your caliper to subtract that measurement. I felt like such a noob when I first used it and got a number way over acceptable headspace.

[stangfish]

The PTG Go Gauge measures 1.561 and the PTG No-Go Gauge measures 1.561. I was wondering how you got your dimensions not the source of your dimmensions. My appologies.


So your gauge... both of your gauges are .011 to .018 short?

1.5792
- 1.561
-------
0.0182

Yikes!! I am not sure of the gauge lengths but the should fall within a very narrow range of tolerences that are close to the cartridges tolerences.

Also when you are using "unfired cases are they new or are they full length sized by you.

This is how my mind has worked out the barrel assembly process. I install the barrel running it up to the gauge where there is light contact between it and the chamber and bolt. I tighten the nut. This will stretch the tolerence a small amount. I retry the bolt with the go and then the no go. If everything is good I will try a piece of brass that is the size I will be using. It usualy goes. I then measure the case headspace. In your case it is 1.5722 - 1.5792. If the case falls under that dimension I know my die is set up wrong. Longer the same thing just the other way.


Now I fire some rounds and take it back and see how far much the case headspace has grown. (The overal length of the cartridge is not an ideal way to determine chamber headspace adjustment) I now adjust my die to bump the shoulder back a maximum of .001 if possible. You can make it bump .000 - .005 if you like. It is your brass and your gun but the principle remains the same.

Good luck and keep us informed. We will get this fixed.

Fish

[bigedp51]

I googled the SAAMI Specs and my reference (p.159) shows 1.5792+.0005 and .347" diameter. Your reference top diagram shows 1.5792-.007 and .347" diameter. The bottom diagram shows X 1.5892 Max and 1.5792 Minimum. I don't know why there is a difference… but I'll swap out my reference for yours. Both refer to the datum line about halfway down the slope of the shoulder. Both reference 1.5792" as minimum.

I used the Stoney Point (Now Hornaday) gauge No. B .350" listed as the correct one for the 250 Savage.
I didn't measure to verify the opening in the gauge itself… but it should be close enough for comparisons.
This will read from the base of the brass to the datum line on the shoulder.

http://www.cabelas.com/tools-accessories-hornady-lnl-headspace-kit-body-1.shtml?WT.tsrc=CSE&WT.mc_id=bingcashback&WT.z_mc_id1=740263&rid=40&mr:referralID=41179de6-c435-11e1-ac63-001b2166c2c0

Go back up and look at the SAAMI drawing, the top is the manufacturing tolerances for the cartridge case, a new cartridge case should be anywhere from 1.5792 to 1.5722 cartridge headspace

The bottom drawing is chamber tolerances and the circle X is headspace dimensions. The chamber minimum or GO is 1.5792, and Field Maximum is 1.5892, it gives no listing for a NO-GO measurement but its normally .003 to .004 longer than GO.

On average a full length resized case is approximately .002 shorter than minimum headspace or GO to ensure a resized case will fit any chamber.

NOTE: I have purchased new cases that were over .009 shorter than minimum headspace, so forget using a new unfired case as a headspace gauge. I would take Blue Avengers advice and use a full length resized case to set your headspace or get your gauge problems sorted out.

[hunter540]

I believe the short readings of the headspace is primarily the fault of the Stoney Point Headspace Gauge inserts themselves.

I checked my Forster 30-06 headspace gauges with the appropriate Stoney Point Headspace insert, and they too read shorter then the SAAMI specs. The inserts work for comparing the growth of brass between unfired and fired brass; for bumping the shoulders back on fired brass when resizing, even comparing the brass to the go gauges… but the numbers won't match up to the SAAMI numbers on the gauge itself. The Forster Go Gauge has 2.0487" stenciled on the side, and my comparator reads 2.03, difference of - .0187. Very close to the same difference on the 250 savage Go Gauge.

The comparator insert must be reading a different point on the shoulder.

For the 250 Savage I made a Go Gauge from fired brass re-sized to the length I wanted. (Recommended by Blue Avenger) and used that to headpiece the barrel. I used the PTG Go Gauge (which I think is too long since the PTG go and No Go Gauges were the same measurement per the Stony Point comparator.) as a No Go Gauge.

All of the new and resized brass feed easily… and if I did it correctly, there should only be .002" or .003" growth when I fire the rounds.

I received the PTG headspace gauges with the 250 Savage barrel I bought online, and I don't know if the previous owner noticed any difference. I'm going to contact PTG to get their recommendations. Till then, I'll be happy with it feeding the brass that I have.

[stangfish]

540. Look like things are good to go


The hornady gauge is a "comparator". Not a accurate deminsional inspection tool. It can wear and chage readings. It does however tell you how similar two or more items are to one another.

[stangfish]

hmmm posting issues

[hunter540]

540. Look like things are good to go


The hornady gauge is a "comparator". Not a accurate deminsional inspection tool. It can wear and chage readings. It does however tell you how similar two or more items are to one another.

Fish,

You're right. When I got the same length for the Go and No go... that started me down the path to the rabbit hole. The reason I got so far into the weeds was I couldn't believe the difference between the SAAMI Specs and the measurements I was getting.

Thank you,

John

[halfmile]

Use a fired case resized in your die and go shoot.

Send the gauge back and get them to measure it.

Life is too short.

HM

[okie2]

the best reply on this thread was from Blue Avenger.
He knows what he is talking about.
Do what he said and throw all your guages in the junk box.