Rem 700 headspace issue

[WalterJones]

I'll try to address the questions without quoting everyone.

-The rifle is fairly accurate. Havent shot it in over a decade but I do remember it shooting right at or just a little better than 1 MOA with Sierra Match Kings.

-The 9 o'clock lug shows the most wear and the 3 o'clock lug the least.

-We did not disassemble the bolt before using the No Go gauge. From this point forward I'll visit a competent gunsmith, regardless if my range official is old enough to have carried a musket in the Revolutionary War

-I wish we had a Randall clone here in northern New Mexico, Randall built an AR for me way back in the day and it ia the most accurate AR I own.

[diver160651]

[ar15barrels]

2) how do you tell when a No Go gauge is really just a Maybe gauge?

Gauge nomenclature and uses are as follows:

GO: Minimum chamber length specification. (also usually happens to be maximum ammunition length specification).

N0-GO: Gauge made up by gauge makers to help gunsmiths check NEW guns.
NEW guns should NOT close on a NO-GO gauge.
Guns can wear BEYOND a NO-GO and still be shorter than the maximum spec.
There is no spec for what the length of a NO-GO gauge is.
Each gauge maker can decide what dimension to use.

FIELD: Maximum chamber length specification.
No gun should accept a FIELD gauge because the FIELD gauge is specified at the dimension where a chamber is considered to be too long to be safely fired.

These specifications and dimensions are all built around the use of factory ammo.
Ammo has it's OWN set of specs that when followed are supposed to produce a safe combination of total headspace clearance.

Reloading allows you to throw all these rules out the door because you can resize your cases to better suit specific guns.

[ar15barrels]

The reason I asked the brand is they dont all measure the same.
A Forester No Go is typically the mid range of saami spec.
So unless you can figure out what gauge you used you havent really any useful info.

Most NO-GO gauges are made to the mid-point of the minimum and maximum specs.
There is no specification called out for what a NO-GO gauge should be.
The NO-GO length is determined by the toolmakers.
I have headspace gauges in 0.001" steps from minimum to maximum for some chamberings.
I often use a GO+ 0.002" gauge as my no-go even though most chambers are going to be GO +0.004" as a typical NO-GO dimension for 0.473" cases or GO+0.003" for 0.380" case heads.

SAAMI headspace gauge specs start on page 224 of this PDF file:

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

Show me where any of them list a NO-GO spec...

[ar15barrels]

Randall who owns AR15 barrels has his websites in his signature line

He provides his costs for working on rifles... you asked what is a typical cost involved- your area and your smiths will charge different.

A 700 is a VERY easy action to tighten up the headspace.
There is typically 0.015" or more clearance between the bolt lug/nose and the back of the barrel.
Headspace is usually within 0.005" or less of minimum.
This means there is room to surface grind the recoil lug a few thousandths to tighten the chamber length closer to minimum.
That will let the barrel screw into the reciever further which effectively shortens the chamber length.

When I cut chambers, I strive to land between minimum and 0.001" longer than minimum.
That means that the bolt handle will drop on a minimum (GO) gauge, but not drop on a GO+0.001" gauge.

[ar15barrels]

-The 9 o'clock lug shows the most wear and the 3 o'clock lug the least.

This is normal in the right handed 700 design.
There is lots of slop between the reciever bore (typically around 0.703") and the bolt body diameter (almost always 0.695").
The cocking piece has an angled surface where the trigger holds the striker to the rear.
This force cams the bolt UPWARDS at the rear of the action.
Since the bolt is floating in the reciever with 0.008" clearance, the rear of the bolt will go all the way UP against the top of the reciever when it's cocked.
The bolt is around 5" long and the bolt lugs are about 1" diameter.
That's a 5:1 ratio.
For each 0.001" off center, the upper lug (9:00 lug becomes the upper lug when the breech is closed) lifts off the lug seat by 0.0002".
As we saw earlier, we have 0.008" total clearance.
Assuming that the front of the bolt sits in the middle of front of the receiver and the back of the bolt is all the way up, that's 0.004" offset or 0.0008" lug lifting off the receiver's lug abutment.

There are easy solutions to fix this problem that only require installing a couple setscrews in the action to reduce most of the bolt body tilt.
Another solution to to get a larger diameter bolt body.
This is usually done during a full blueprinting (truing) of the action.
Taking the bolt body clearance down to 0.0015" to 0.002" total gets rif of 3/4 of the lug lift off.
Then lapping the lugs under cocking piece tension gets rid of the rest, ensuring full contact of both lugs.

[divingin]

I have headspace gauges in 0.001" steps from minimum to maximum for some chamberings.

That's an interesting tidbit. Did you make these or buy them? Or have them made?

[Fjold]

Excess headspace is only an issue with factory ammunition. Reloaders adjust their sizing dies to fit their chambers.

[ar15barrels]

That's an interesting tidbit. Did you make these or buy them? Or have them made?

I bought them.
Brownells 079-308-000WB is a 308 family set which covers 243, 260, 7-08, 308, 338 federal and 358 winchester chambers.

[LynnJr]

You can also buy recoil lugs from Pacific Tool with 0.001 increment steps.