338 Fed Barrel Chambering Issue Followup

[mioduz]

Previously posted that I am having a hell of a time chambering a new barrel in 338 Federal

Utilizing .308 Gages
To summarize I chambered to where the go gage closes with no resistance and the NO GO locks up tite. Luckily I tested a peice of new Federal brand Ammo in the chamber before removal from the lathe. It would not close.
I can put the case in and out without any drag on the chamber

After messing around for what seams like an eternity, I could not get this action to chamber the live round (or a peice of pulled brass) without it closing on the NO GO gage.


I had enough of this BS, and measured my NO GO gage and the Loaded rounds Head space
Using a .420 bushing
the NO GO measures 1.604
The loaded round measures 1.6035
So my loaded ammo (and my my nogo gage have nearly identical head space length)
This explains why I cannot find a happy spot for the cartridge without exceeding the NO GO.

I assumed that the Ammo was out of spec or at very least on the VERY high end of acceptable

I referenced the SAMI Spec for 338 Fed Cartridge

Per the Print cartridge headspace dimension is 1.607-.007 (I read that as 1.6-1.607 is acceptable)

Multiple locations reference using a 308 gage set FOR .338

Looking at the sami spec I see that the 308 uses a .400 dia Datum for Headspace and the .338 uses a .420 Datum. I felt like that was kinda odd that they can share the same gage, with different datum points


Any advice?????

 

[Supersubes]

You had said that the cartridge would fit if you forced it. That means you're with .001-.002 of it closing. Run the chamber deeper .001 at a time until it closes. If you cant do .001 increments, do .002. If it closes with an additional .002 on it, and you run an additional .002-.004, all is well.

 

[mioduz]

You had said that the cartridge would fit if you forced it. That means you're with .001-.002 of it closing. Run the chamber deeper .001 at a time until it closes. If you cant do .001 increments, do .002. If it closes with an additional .002 on it, and you run an additional .002-.004, all is well.

The problem is the NO GO then fits. They have nearly the same head space measurement

 

[Supersubes]

Your nogo is clearly bad though, yes? Edit: i misread, nogo and cartridge are the same. My point stands though, you have out of spec gauges or ammo. You can chamber for the ammo, or buy new gauges and check again.

Is this a personal gun or customer gun?

 

[mioduz]

Your nogo is clearly bad though, yes? Edit: i misread, nogo and cartridge are the same. My point stands though, you have out of spec gauges or ammo. You can chamber for the ammo, or buy new gauges and check again.

Is this a personal gun or customer gun?

Customers

looking into the issue further using a .400 bushing my NO Go Gauge 1.630 however its etched 1.634 on side

 

[Supersubes]

Customers

looking into the issue further using a .400 bushing my NO Go Gauge 1.630 however its etched 1.634 on side

Can you get your hands on more factory ammo?

 

[mioduz]

Can you get your hands on more factory ammo?

lmao....thanks i needed a good laugh

i can tool around online and see what i can find, but per the sami spec if im reading this correctly, its all good

 

[Supersubes]

It’s in stock at Midway. If you can get any other ammo even with the same line, but different lot number, and you find that it’s the same size as what you got, chamber to the ammo. Customer not have any ammo? Virgin Brass?
And if customer is simply going to hand load this, leave it. He can size to fit the current chamber.

 

[mioduz]

It’s in stock at Midway. If you can get any other ammo even with the same line, but different lot number, and you find that it’s the same size as what you got, chamber to the ammo. Customer not have any ammo? Virgin Brass?
And if customer is simply going to hand load this, leave it. He can size to fit the current chamber.

Customer doesn't hand load, nor does he have any ammo as his house burnt down (why he wants a 338 fed is beyond me)

 

[mick243]

ok, its about 20 years or so since I last did this stuff for money....

BUT, back then your " NO GO locks up tite " would have been considered wrong, where I was working it was a case of "go" guage the action *must* lock effortlessly, "no-go" the action *must not* close/lock.


although the 338fed was made from 308 cases, there is the possibility that your 308 gauge set is wrong for the fed (I doubt, but possible) can you get a set of gauges for the fed?

have you used something like a case comparator to measure the difference between your gauges and the factory ammo?

 

[mioduz]

ok, its about 20 years or so since I last did this stuff for money....

BUT, back then your " NO GO locks up tite " would have been considered wrong, where I was working it was a case of "go" guage the action *must* lock effortlessly, "no-go" the action *must not* close/lock.


although the 338fed was made from 308 cases, there is the possibility that your 308 gauge set is wrong for the fed (I doubt, but possible) can you get a set of gauges for the fed?

have you used something like a case comparator to measure the difference between your gauges and the factory ammo?

Your description of go and no go is exactly what I am trying to achieve.


Yes I have compared them and all the measurements are in the first post of this thread

 

[mick243]

Your description of go and no go is exactly what I am trying to achieve.


Yes I have compared them and all the measurements are in the first post of this thread

duh - serves me right for not proof reading my comment!


but those measurements the ammo is shorter ( by about half a bees dick) than the gauge, yet the bolt closes on the gauge but not the ammo - something there sounds screwy, and my guess is that whoever cut the gauge (or the die the ammo was made in) was off in the shoulder angle ever so slightly compared to whoever cut the chamber reamer, with your comparator, can you measure the gauges and the ammo with smaller and larger than normal comparators? (because they can only measure datum lines and not the angles... but I'm thinking that the difference in length (according to the chamber) is at some other spot on the shoulder angle)

another possibility - measure the width of the case and the gauges at the actual shoulder, there is a very slim possibility that this might be where things bind up. another slim possibility is the neck of the chamber (neck a bit short compared to brass, brass a bit fat compared to neck etc)

have you coloured in a case with a sharpie to see where it rubs off when chambering?

as to your question of the difference in datum lines in the saami spec - yeah it shouldnt matter if the angles are precise, it might just have been what measurement guages the person writing the spec happened to use on the day OR they may have had a good reason for the difference (and we just dont know what it was) - but this might mean that the difference between 308 chamber gauges and fed chamber gauges matters. (does anyone here have both sets of gauges and can measure them at both 0.400 and 0.420 datums?)

 

[msgriff]

I don't know if this helps, but there's a difference between the Forster (1.634") and the PTG (1.635") NO-GO gauges when measured from the .308 datum (0.400"). I have also read that the Clymer NO-GO is1.636". Just noting the range between manufacturers.

 

[mioduz]

duh - serves me right for not proof reading my comment!


but those measurements the ammo is shorter ( by about half a bees dick) than the gauge, yet the bolt closes on the gauge but not the ammo - something there sounds screwy, and my guess is that whoever cut the gauge (or the die the ammo was made in) was off in the shoulder angle ever so slightly compared to whoever cut the chamber reamer, with your comparator, can you measure the gauges and the ammo with smaller and larger than normal comparators? (because they can only measure datum lines and not the angles... but I'm thinking that the difference in length (according to the chamber) is at some other spot on the shoulder angle)

another possibility - measure the width of the case and the gauges at the actual shoulder, there is a very slim possibility that this might be where things bind up. another slim possibility is the neck of the chamber (neck a bit short compared to brass, brass a bit fat compared to neck etc)

have you coloured in a case with a sharpie to see where it rubs off when chambering?

as to your question of the difference in datum lines in the saami spec - yeah it shouldnt matter if the angles are precise, it might just have been what measurement guages the person writing the spec happened to use on the day OR they may have had a good reason for the difference (and we just dont know what it was) - but this might mean that the difference between 308 chamber gauges and fed chamber gauges matters. (does anyone here have both sets of gauges and can measure them at both 0.400 and 0.420 datums?)

Bolt closes on the 308 GO gauge, right now is very tight on both the NO GO and Live Round (expected after taking measurements)

I plan on doing the Trig to verify that the .400 gage line on 308 vs .420 gage line on 338 fed lengths are coincident on the angled surface (for the different lengths of course)

 

[Edds]

What is the difference in the length of your GO vs NO-GO gauges?

 

[mioduz]

What is the difference in the length of your GO vs NO-GO gauges?

.004

 

[Edds]

If your measurements are accurate, your gauges are short.

The ammo should be somewhere between 1.600" and 1.607".

The chamber should be somewhere between 1.6025" and 1.6125".

The GO gauge should not be shorter than minimum chamber spec. The NO-GO should be shorter than the maximum chamber spec.

GO plus .004 is fine for a NO-GO.

Have you tried any 308 ammo in the chamber?