Bolt Safety Lug Riding Against Shoulder

[NMC_EXP]

I've developed an interest in M1903 based vintage target rifles. There is one in a shop locally. It is a "high number" SA receiver, heavy aftermarket barrel in .03/06, international style stock. Just took a quick look and did not check the headspace.

I had one immediate concern: The bolt safety lug is bearing on it's shoulder in the receiver. I'm just a trigger puller, and not a rifle mechanic but what I've read says that by design there should be clearance between the bolt safety lug and the shoulder. If there is no clearance then the single safety lug is taking the bolt thrust rather than the two locking lugs. This is a safety problem.

Questions are:

(1) What are possible causes? - bolt and receiver set back due to heavy loads? Too much bolt lug polishing? Bolt swapping...etc?

(2) Is it fixable by swapping bolts?

I'm thinking if just the bolt locking lugs were set back due to heavy loads, swapping bolts might work.

If the receiver shoulders were set back or polished excessively, it is not fixable.

Opinions will be appreciated.

Regards

JIm

[dave]

I would check headspace and another bolt before I purchased it. If its "set back" from wear I would not want it

[purple]

If you are getting hard contact between the rear face of the safety lug and the receiver it will not be possible to get an accurate headspace reading with the existing bolt. You could remove enough metal off the rear face of the safety lug to establish some clearance and then check headspace with the existing bolt.

Could be that the lug seats in the receiver are set back to the point where contact is occuring on the rear of the safety lug. I'd also try checking headspace with a replacement bolt that does not have the safety lug in contact. If headspace is excessive on the "field" gauge, a field test bolt used with the "field" gauge will indicate if either the bolt lugs or the receiver lug seats are worn to the point of unservicability. If the field test bolt bolt does not close on the "field' gauge, a worn bolt is indicated. If the field test bolt does close on the "field" gauge, this will indicate either an excessively deep chamber or, more likely, worn bolt lug seats in the receiver.

[NMC_EXP]

If headspace is excessive on the "field" gauge, a field test bolt used with the "field" gauge will indicate if either the bolt lugs or the receiver lug seats are worn to the point of unservicability. If the field test bolt bolt does not close on the "field' gauge, a worn bolt is indicated. If the field test bolt does close on the "field" gauge, this will indicate either an excessively deep chamber or, more likely, worn bolt lug seats in the receiver.

I have a set of Forster headspace gages, but no field test bolt.

I did not know that a field test bolt could be used to distinguish between bolt and receiver wear.

If in fact worn receiver seats are the problem, does that make the receiver unserviceable (even with a new bolt and new barrel chambered to the bolt)?

Regards

Jim

[purple]

GPC is listing new field test bolts for $20.55, a pretty good bargoon. I don't know if there is a measurable limit of acceptable set back on the lug seats. The field test bolt, when used with the "field" headspace gauge, establishes an absolute go/no-go measurement on this though. I have a 1918 vintage hi number receiver which shows visible set back on the lug seats, but no contact with the safety lug of a bolt. I am looking at installing a new barrel and finish reaming it to set up proper headspace. Incidentally, the amount of minimum clearance stipulated between the rear of the safety lug and the receiver is .004.

[JOHN COOK]

I thought .003 was minimum clearance stipulated between the rear of the safety lug and the receiver. I think I saw a photo in Brophy showing a field repair kit with a .003 feeler gage to be used when checking in the field....

john

[chuckindenver]

try another bolt, you can use the standard Field reject gauge with your bolt...
No Go would be my choice to use.
should be a slight gap, usaully from bolt setback, from manual of arms use, opening the bolt hard against the ejector for arms inspection.

[purple]

FWIW a .004 thickness gauge for this purpose is cited in an article from the Army Ordnance Magazine July-August 1928 Vol. IX, No 49 which is titled "Overhauling the Service Rifle", by Lt J.E. McInerney. This article is re-printed in its entirety in the book, "Manufacture of the Model 1903 Springfield Service Rifle" by Wolfe Publishing Co. Inc. 1984. This book is a treasure trove of original manufacturing specs and processes for the M1903. Brophy's book also contains extracts from the McInerney article and does mention the .004 gauge as well.

[Emri]

" If the receiver shoulders were set back or polished excessively, it is not fixable. "


That is correct.

[Fred]

Don't do like I used to when just a dumb ass kid and whack the set back bolt lugs with a hammer on the end to expand them and then dress the overage slightly with a file and emery until it head spaced right. And this was done on my early 05 dated barrel, solid hand guard, no stock bolt rifle with the 4 digit numbered receiver. Always check those receivers if you change bolts. You never know who did what to a rifle! Yea, I used to shoot it too back in the day, in the early 70's.

[JOHN COOK]

Purple, you are correct, it is .004 not .003. I had it marked in Brophy and read it again . I was interested in that measurment and Fred Guffy responded to a question I posted several years ago.

Thanks for correcting me,
john

[NMC_EXP]

Thanks to all for the excellent info.

Sounds like I need to scrounge up some more books.

Think I'll pass on this rifle.

Regards

Jim