Buddy brings over the M70 300 Win Mag pushfeed he bought "walking around" at a gunshow, wants me to adjust the creep out of the trigger. I notice that the number electropenciled on the bolt doesn't match the s/n on the reciever. It is a 100% Winchester PF factory bolt. Hmmm. It swallows a Forster No-Go headspace gauge (0.223) After messing around with some shims on the boltface I think the headspce is about 0.228. What do you think? I have shot some belted mags with excess headspace ,stretches the brass and decreases case life but they shot ok. Any help appreciated. Thanks, Russ Green.

If the gun were mine I would probably use only my own reloads that were headspaced on the shoulder for this particular gun. Even for the first firing. Sometimes factory belted rounds are close at the shoulder and sometimes they're not, and it can vary between brands. I would definitely be careful because head seperations are not fun.

BigRx

The chamber tolerance is .220" -.227". So .228" is just fine IMHO. I never measured a factory belted chamber that was in tolerance anyway.

Using a feeler gage with belted cases goes with the territory. Just set the FL die right and keep checking.

While your at working on that rifle do a drop test on the trigger work.

Others can make their own belted case headspace gage. Just put a dab of soft solder on the side of a case at the top of the belt, file it some, chamber it and then measure it.

Mags can be a little tolerant in headspace.
.003" is I would say right at the max I would shoot.

Make up some way way reduced loads and try it out.

-Spencer

quote:

Originally posted by Head Trauma:
Buddy brings over the M70 300 Win Mag pushfeed he bought "walking around" at a gunshow, wants me to adjust the creep out of the trigger. I notice that the number electropenciled on the bolt doesn't match the s/n on the reciever. It is a 100% Winchester PF factory bolt. Hmmm. It swallows a Forster No-Go headspace gauge (0.223) After messing around with some shims on the boltface I think the headspce is about 0.228. What do you think? I have shot some belted mags with excess headspace ,stretches the brass and decreases case life but they shot ok. Any help appreciated. Thanks, Russ Green.

There's NO F WAY, i would shoot that rifle as you have presented it.

Do you have a forester GO gauge?

generally, .005 is the MAX from go to no-go... and what you have described is TWICE that... .010....

that's HUGE...

cerrosafe and measure the chamber, if notthing else

jeffe

Oh crap.

Thanks for bringing that up Jeffe.

Please disregard my previous post, .010" excessive headspace is trouble.

I really would not even bother casting the chamber.

Take it to a gunsmith and have the barrel set back and rechambered.

-Spencer

quote:

Originally posted by jeffeosso:

quote:

Originally posted by Head Trauma:
Buddy brings over the M70 300 Win Mag pushfeed he bought "walking around" at a gunshow, wants me to adjust the creep out of the trigger. I notice that the number electropenciled on the bolt doesn't match the s/n on the reciever. It is a 100% Winchester PF factory bolt. Hmmm. It swallows a Forster No-Go headspace gauge (0.223) After messing around with some shims on the boltface I think the headspce is about 0.228. What do you think? I have shot some belted mags with excess headspace ,stretches the brass and decreases case life but they shot ok. Any help appreciated. Thanks, Russ Green.

There's NO F WAY, i would shoot that rifle as you have presented it.

Do you have a forester GO gauge?

generally, .005 is the MAX from go to no-go... and what you have described is TWICE that... .010....

that's HUGE...

cerrosafe and measure the chamber, if notthing else

jeffe

I don't agree. If he measured .228" and the chamber tolerance is .220" to .227" it's only .001" off!

I think it's safe and common.

Jeffe,

What do you say the chamber tolerance is?

If it turns out that it's not safe I would contact a Winchester service center for a free repair.

Savag99,
I think you are right but I stay out of most head space discussions and usually just take in the information.

Since the serial # is different on the bolt from the action, I doubt that Winchester will give you a free head space correction.

Savage99..

he says is swallows a NO GO...

that means it's excessive headspace...

say, well, that the nogo ga is a little short... which is +.005 from minimum... so, let's say it's .0035 rather than .005... the feeler ga is STILL .005 langer...

so, let's say (so it's easier to layout)
if the no-go is .005 longer than zero headpspace....

the current reading is DOUBLE that ...

and if it was a .0035 headspace, it's THREE TIMES acceptable..


here's my thoughts...

if .005 is too long,
.010 is WAY too long...

I don't make the rules, i just try to live within them.

*** i would not shoot this rifle and the followinig is NOT a shooting suggestion***


here's my thoughts if this rifle was fired... and reloaded...

first loading.. problably okay..
second loading (assuming partial sizing), probably okay
third loading... case seperation...

there's a reason that a go ga is okay and no-go means it's too big...

just my thoughts

jeffe

jeffe,

If this were basketball I would say that you have faked me out.

Since it's not basketball but chamber dimensions I use .004" over a Foster no go as my maximum for rimless cartridges. The greatest belted headspace that I own is .228" and it's also the tightest I have measured of two factory pre 64 M 70's with orginal bolts. These rifles work fine.

Savage99,
no faking was intended. If *I* cut a chamber that was .010 larger than ZERO i would have to setback and recut...

jeffe

Headspace can be pretty tricky.

Here are my rules in a perfect:

000 = GO

GO + 003 = Max safe shootable

NO GO (GO + 005) = Unsafe

NO GO + 005 = KABOOM!

To really measure reliable headspace, you need to use a brass case or a loaded round and then shim it up.

-Spencer

Here is Fosters page on headspace gages.
Headspace Gages
The best way to check your rifle chamber for safety.




Every gunsmith knows that proper use of a headspace gage is the most reliable way to test the length of a rifle chamber. "Headspace" is the distance between the face of the breech and the base of the cartridge when the action is closed, and excessive headspace can be dangerous as well as impair accuracy. For instance, unsupported brass fired in a rifle action with excessive headspace can rupture, allowing gas to blow rearward like a rocket exhaust. Because your safety is on the line, Forster Headspace Gages are made with painstaking care and exacting manufacturing standards to ensure accurate testing of your rifle's chamber.

Important Guidelines For Measuring Headspace:

If a rifle closes on a GO gage, the rifle chamber will accept any ammunition that is made within S.A.A.M.I. (industry standard) specifications.
If a rifle closes on a NO GO gage, the rifle chamber might have excessive headspace. Most gunsmiths chamber a rifle's headspace between the GO and NO GO dimensions.
If a rifle closes on a FIELD gage, rifle chamber is dangerously close to or already over the S.A.A.M.I. specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been repaired.
When checking headspace, a stripped bolt and removal of the firing pin will make it easier to feel the action closing on the gage. Some shooters are under the misconcenption that the headspace of a gun is fixed over the life of the firearm. Headspace can increase after repeated use of ammunition that causes too much pressure. Handloaders should routinely check headspace every thousand rounds.
Headspace Gages for Rimmed Calibers
Caliber GO
Length GO
Order no. NO GO
Length NO GO
Order no. FIELD
Length FIELD
Order no.
219 Wasp & Zipper .063†BG3030G .067†BG3030N .070†BG3030F
22 Sav. H.P., 25-35 .063†BG3030G .067†BG3030N .070†BG3030F
30-30, 32 Win. Sp. .063†BG3030G .067†BG3030N .070†BG3030F
32-40, 38-55 .063†BG3030G .067†BG3030N .070†BG3030F
22 Rimfire .043†HG22RimG .046†HG22RimN .049†HG22RimF
300 Mag. & all belted Mags .220†BG300MG .223†BG300MN .226†BG300MF
7.62 X 54 Russian - - .071 BG762RN .074 BG762RF
303 British .064†BG303G .067†BG303N .070†BG303F
30-40 Krag .064†BG3040G .067†BG3040N .070†BG3040F
30 Carbine 1.290†HG0030G 1.296†HG0030N 1.299†HG0030F



Headspace Gages for Rimless Calibers
Caliber GO
Length GO
Order no. NO GO
Length NO GO
Order no. FIELD
Length FIELD
Order no.
22-250 Remington 1.574†HG2225G 1.579†HG2225N 1.583†HG2225F
22 PPC 1.145†HGOPPCG 1.149†HGOPPCN 1.154†HGOPPCF
220 Swift 1.806†HG0220G 1.810†HG0220N 1.814†HG0220F
222 Remington 1.294†HG0222G 1.297†HG0222N 1.300†HG0222F
222 Remington Magnum 1.493†HG222MG 1.496†HG222MN 1.499†HG222MF
223 Remington* 1.464†HG0223G 1.467†HG0223N 1.470†HG0223F
243 Winchester 1.630†HG0243G 1.634†HG0243N 1.638†HG0243F
308 Winchester 1.630†HG0243G 1.634†HG0243N 1.638†HG0243F
358 Winchester 1.630†HG0243G 1.634†HG0243N 1.638†HG0243F
7mm-08 Rem. 1.630†HG0243G 1.634†HG0243N 1.638†HG0243F
1.630†HG0243G 1.634†HG0243N 1.638†HG0243F
244 Remington 1.777†HG0244G 1.781†HG0244N 1.785†HG0244F
250 Savage 1.579†HG0250G 1.583†HG0250N 1.587†HG0250F
6mmPPC 1.145†HGOPPCG 1.149†HG0PPCN 1.154†HGOPPCF
6.5 SKAN 1.831†HGSKANG 1.835†HGSKANN Not Available
6.5 x 55 Swede 1.779†HG6555G 1.785†HG6555N 1.789†HG6555F
257 Roberts 1.794†HG0257G 1.800†HG0257N 1.804†HG0257F
7mm Mauser 1.794†HG0257G 1.800†HG0257N 1.804†HG0257F
280 Remington 2.100†HG0280G 2.104†HG0280N 2.108†HG0280F
284 Winchester 1.810†HG0284G 1.815†HG0284N 1.817†HG0284F
25-06 2.049†HG3006G 2.055†HG3006N 2.058†HG3006F
270 Winchester 2.049†HG3006G 2.055†HG3006N 2.058†HG3006F
30-06 Springfield 2.049†HG3006G 2.055†HG3006N 2.058†HG3006F
8mm x 57 Mauser** 1.874†HG8x57G 1.880†HG8x57N 1.884†HG8x57F
* A special, longer (field reject) gage is available. Order No. HGO223R
**This gage is for checking current S.A.A.M.I. specified 19° shoulder angle. Some older rifles were chambered to 20° 48’. Special gages are available.



Headspace Gages (Go,NoGo,Field) $23.50/ea

Rimmed (Button) Gages (Go,NoGo,Field) $23.00/ea

Exception: 30 Carbine (Go,NoGO,Field) $29.50/ea


Gunsmith/Firearms Maintenance Tools & Equipment Price List

Savage99,
so, forestor says .220 go, .223 no-go, and .226 field ( If a rifle closes on a FIELD gage, rifle chamber is dangerously close to or already over the S.A.A.M.I. specified maximum chamber size)

then a .228 is probably bad, wouldn't you agree?

jeffe

Jeffe,

That information from Foster on the belted gages is new to me. From what it says I have to go with it.

I am at the information stage where I don't have a belted headspace gage but I have made soldered gages as I mentioned before. I also have the chamber drawings for the various belted magnum rounds and that's listed at .220" to .227" as I mentioned before. Finally the two pre 64 M70's that I have checked with my home made "gage" both measure .228" and these rifles have their original barrels and the chamber, shoot and reload fine within the context of the belted handloading reality.

If I were to chamber a barrel such as you do and have my name on it like you do I would go by what Foster writes and what you are doing of course.

What do the Foster gages really measure? Do you have a gage mic. or Jorgenson bocks and a surface plate? I was thinking of making a No Go and seeing if it got a different result from the soldered case gage.