Determining Headspace ETC... ETC

[nf1e]

Well, I guess that's that then.
Back to the loading bench tho old fashioned way.
Some live in a very lonely world by choice.

[togor]

Is that a Canadian joke?

If not I have been doing it wrong for over 50 years my friend. This is a critical measurement that is easily checked with proper equipment. There is chamber headspace measurement and cartridge headspace measurement. I like to set my cartridge headspace .004 under chamber headspace for auto-loaders and a little tighter for bolt rifles.

Headspace = distance between the bolt face and a datum line (determined by SAAMI) where the front of the cartridge rests on its shoulder when the bolt is closed.

This.

I have a G43 with very long headspace. Brass is resized .30-06 resized to 7.92x57mm. Resize long to the chamber by adjusting the height of the resizing die in the press. Seems obvious enough.

[nf1e]

Can't make it so easy, everyone would want to join the foray. Maintaining the mystique should be left to the most creative minds that like to ruin everything with technical interpretations that only a few could possibly understand, and normal folks could care less. I just like things as they appear to be, not as they truly are.

[lyman]

This.

I have a G43 with very long headspace. Brass is resized .30-06 resized to 7.92x57mm. Resize long to the chamber by adjusting the height of the resizing die in the press. Seems obvious enough.

many moons ago I was a true believer,
set to SAAMI spec, and if a firearm failed headspace then part it out, rebarrel, etc etc , it was toast,
whoa is me, etc etc


then, when I started reloading (not quite as many moons ago, but a good while ago) I learned different,

load safe, watch for pressure signs, enjoy

[fguffey]

This.

I have a G43 with very long headspace. Brass is resized .30-06 resized to 7.92x57mm. Resize long to the chamber by adjusting the height of the resizing die in the press. Seems obvious enough

. Togar, The difference in length between the 8MM 57 and the 30/06 from the datum/shoulder to the bolt face is .127” (+/- a few.) I understand the instructions for forming 30/06 cases to 8 MM 57 cases start with “All you got to do is etc. etc.”, after that the honesty of the reloaders goes out the window.

I have formed thousands of 8MM57 cases from 30/06 cases because; after the forming die is paid for 8MM57 cases cost me seven cents each. Without the forming dies the cost goes out of sight. Without the forming die the cases look as bad as roll your own cigarettes.

I have long chambers; because I have no phobia about ‘the datum’ I determine the length of the long chamber from the shoulder/datum to the bolt face. After determining the length of the chamber from the shoulder to the bolt face I adjust the forming die to off set the length of the chamber when forming cases; as we (all should know) after forming the case must be sized for final fit. I have asked many times where the .002” die adjustment come from did.

And I always ask how can a reloader miss when the parent case is .127” longer than the case being formed from the shoulder of the case to the case head? This questions has cause many reloaders to have sagging shoulders and a reseeding hair line. Not my fault. In the beginning I used .003”.

F. Guffey

[togor]

I do this:

1. Rough cut about 3/16" off the .30-06 case neck.

2. Anneal the area around the shoulder with my plumbing torch.

3. Lube the cases. A heavy lube seems better than One Shot for this.

4. Put my 8x57 sizing die in the press. I use a feeler gauge between the bottom of the die and the top of the shell holder to increase distance from case head to the shoulder.

5. Trim with the length adjusted to include feeler gauge blade of choice.

Beyond that just load and shoot normally. A G-43 being a hard to replace item my loads are on the light end, and I put a restrictor in the gas piston throat (a steel blind rivet works great).

I'm probably doing it wrong but when I pull the trigger, the cases aren't asked to stretch much during obturation.

[lyman]

I do this:

1. Rough cut about 3/16" off the .30-06 case neck.

2. Anneal the area around the shoulder with my plumbing torch.

3. Lube the cases. A heavy lube seems better than One Shot for this.

4. Put my 8x57 sizing die in the press. I use a feeler gauge between the bottom of the die and the top of the shell holder to increase distance from case head to the shoulder.

5. Trim with the length adjusted to include feeler gauge blade of choice.

Beyond that just load and shoot normally. A G-43 being a hard to replace item my loads are on the light end, and I put a restrictor in the gas piston throat (a steel blind rivet works great).

I'm probably doing it wrong but when I pull the trigger, the cases aren't asked to stretch much during obturation.

slightly of topic,

have you thought of installing a shooters kit on that G43?

[togor]

slightly of topic,

have you thought of installing a shooters kit on that G43?

I did and actually did some business with Rob (good guy), but for as little as I shoot this gun, the rivet option gives me a nice impulse reduction. I forget the size I use but the effect is that the bolt picks up the next round but doesn't bang hard against travel limits.

[lyman]

I did and actually did some business with Rob (good guy), but for as little as I shoot this gun, the rivet option gives me a nice impulse reduction. I forget the size I use but the effect is that the bolt picks up the next round but doesn't bang hard against travel limits.

what kind of lifespan are you getting out off the rivet?

[togor]

what kind of lifespan are you getting out off the rivet?

No deformation in version #2 after 25 rounds. Version #1 had the flange deforming to the conical shape of the piston throat. The difference was the length of the rivet. I trimmed back #2 to about 1/4" (roughly half the length), so the pressure drop across the restrictor is reduced. By folding back the shaft at the blind end (after a crosscut), it makes for a friction fit in the piston. This is not service grade but again for as little as I shoot the gun it is fine. It may not go out again for 3 years. G43s are tough on brass in extraction so before shooting again I'll have to make more anyways. Some parts do get swapped out for shooting, and IMO the best way to store it is with the bolt disassembled and the springs relaxed. It works for me. The ZF-4 is dialed in now so that 38gr of Varget with a 200gr HPBT gives decent groups. It's a fun day when it goes to the range.

[fguffey]

4. Put my 8x57 sizing die in the press. I use a feeler gauge between the bottom of the die and the top of the shell holder to increase distance from case head to the shoulder.

Redding sells shell holders that increase the deck height of the shell holder, I have never found it necessary to use the Redding Competition Shell holder because I adjust the die off the shell holder with a feeler gage. After making the adjustment I secure the die to the press with the lock ring.

F. Guffey