Bolt interchangeability

[6thMARDIV]

How safe is it to randomly interchange bolts between '03's without head spacing ? I saw this done on a couple of rifles at a WW1 Re-enactment this weekend. They were of course shooting blanks.

[mhb]

It isn't 'safe' at all...

because there is no way to know that the wear on either of the receivers or bolts is the same - and you may be sure that nearly all 1903 receivers and most of the bolts are worn to some extent - nor that either of the original assemblies were within the proper range of headspace in the first place.
Remember that the bolts were selectively fitted in rebuild when the barrel was not replaced, and that, any time the barrel was replaced (or in new manufacture), the chamber was reamed to be within tolerance with the selected bolt, which might be new or used.
It is also true that receivers and bolts, new or used, were gauged to determine whether they were within permissible tolerance ranges before they were assembled, and that those parts which did not pass gauging were scrapped, but hardly anyone assembling 1903's these days has the means to do more than attempt to keep headspace within the proper limits with available parts.
At this late date, all that most users can do is check that headspace is correct in existing rifles, and change bolts or rebarrel to keep them so - otherwise, all bets are off.
Interchanging bolts without checking headspace, even for arms used only with blanks, is bad practice.
mhb - Mike

[Johnny in Texas]

I quick check method to check headspace on '03 rifle is to remover the firing pin assembly from the bolt it just unscrews and remove the extractor.. Then using a new factory live round and a small piece of note book paper put the live in the chamber with the small paper just smaller than the case head stuck to it with saliva or what ever you have not glue. then install the bolt and slowly start to close the bolt with a very light touch. You should feel resistance before the bolt closes or about half closed is best. If it closes do not fire the rifle. This is just a quick method see if it is close or over.

[mhb]

Well...

since the average piece of paper measures .003" - .004", the maximum cartridge headspace (longest permissible cartridge case) is on the order of +.001", and the minimum to maximum permissible variation ('Go' to 'No Go') is .006" in the rifle, not to mention that the 'Field' gauge is .010" over the minimum (and is used only to determine when the headspace has become too long for military serviceability), that is a pretty rough test.
Indeed, any error (closing on the combination suggested) would likely be on the safe side, but would not actually demonstrate that the headspace was unsafe or excessive. Better to stick with the proper gauges.
mhb - Mike

[dave]

Glad to see someone else state that a 'field gauge' is not acceptable as "safe" indication. I have had many arguements over this! I have read (may have been Hatcher) that if rifle closes on a 'field' gauge it can be used till it can be returned for repair. Thats why its called a field gauge---to be used only when you are stuck in the field and may need a rifle!

[chuckindenver]

Go...should close easy and smooth
No go..should not close....hinse the term NO GO.
Field Reject...should not close. the term REJECT comes to mind.
likely most bolts in good working order should swap rifle to rifle, however, a No go gauge should be used.

[fguffey]

[QUOTE=mhb;303071]because there is no way to know that the wear on either of the receivers or bolts is the same - and you may be sure that nearly all 1903 receivers and most of the bolts are worn to some extent - nor that either of the original assemblies were within the proper range of headspace in the first place.
--------------------------------------------------------------------------------------------------------------------

Mot true, a more true statement would go more correctly when stated

It is possible for me to remove a bolt from a chamber with a know chamber length and measure the effect it had on head space then order another bolt that had a greater ability to off set the length of the chamber from the the shoulder of the chamber to the bolt face, PROBLEM! Finding someone else that could measure a bucket of bolts to determine which bolt would off set the length of the chamber as in decrease the length of the chamber or increase the length of the chamber.

A few years back a shooter, reloader builder of period correct military rifles was building a period correct 1911 Rock Island 1903 rifle, he was making every attempt to work with a 1903 Forum, then the word ‘head space’ came up, then it became a dysfunctional 03 forum, anyhow, I purchased a mill from him about that time. We loaded it and rounder up a few related pieces. Then the subject of head space came up, I informed him “THIS IS YOUR LUCKY DAY”. I informed him I could check the length of the chamber three different ways, all I needed to was time to check his walls, benches and tool boxes for tools, sure enough, he had a feeler gage and the ammo he was going to use to test fire the rifle with.

I checked the effect the chamber was going to have on his new, minimum length/full length sized cases, the difference between the length of his chamber and the length of his cases was .0075, in the perfect world that number would have been .005”. He wanted to reduce the .0075. Not a problem, he did not have less than 70 bolts, I offered to test all of them, I offered to return home and measure my bolts (without his rifle), I have no less than 35 03 type bolts. Back to ‘problem’, his Rock Island was to be period correct, that meant he needed a straight handle. He did not have another straight handle, I do/did not have a straight handle, I assured him I did not have a bolt that would correct .0025” head space, I had already measured them. The same man building the period correct rifle recorded all the information from my bolts and then added to a data base.

NOW? He has at least 5 straight handle bolts that he acquired from other collectors/builders.

F. Guffey

Length of the chamber from the shoulder/datum to the bolt face, the case does not have a head space designation, only a case length from the datum to the head of the case.

[fguffey]

Again, the 03 is unique, Springfield did not build the design into the rifle, it was an accident, Hatcher did not notice it, but the bolt on the 03 is limited when moving to the rear, the bolt stops when the bolt lugs make contact, that is the same for all rifles, difference? The 03 bolt, not by design, moves forward, to limit the forward movement the proud owner can chamber a round,, OR! a head space go-gage OR! a no go-gage.

Again, not by design, the 03 has an exposed 3rd lug with a gap between the front of the rear receiver ring and the back of the lug, the gap is less with the old bolts than the newer 03A3 bolts, to determine the difference in length between the chamber and and case length seat the bolt to the rear and measure the gap, then push the bolt forward and measure the gap again, the difference in the two gaps with the head space gage(s) or case chambered equals the difference in length between the case and chamber in thousandths.

It is not necessary to be the first to post “When checking head space? remove the firing pin assembly and and extractor” Removing the firing pin assemble and extractor is not necessary.

F. Guffey

[mhb]

fguffey:

I think you're getting wrapped around the axle on points that have nothing to do with the original question: is it safe to interchange bolts among 1903 rifles.
My answer was no, and I gave some of the reasons why that is so for the average user(s) - what a knowledgeable person can do with the proper equipment and parts is another matter.
Later, someone posted a rough method of testing headspace, which I also commented on.
My comments on the state of wear on existing receivers and bolts are correct: I've assembled, rebarreled and worked on a large number of 1903 rifles of all vintages and types. I have the means to measure any and all of the critical dimensions of the receiver and bolt, and have some of the original Ordnance gauges and tools and enough parts to assemble a number of complete rifles with either brand-new or used parts (though I do not currently have a spare new receiver, I have had several spare parts and sales receivers in the past).
I have also encountered bolts with enough wear to the locking lugs to permit the safety lug to bear on the receiver, though the minimum clearance is specified as .004" - such bolts should be scrapped, because that is a known unsafe condition, and even though the safety lug might be ground shorter to restore the clearance and a new barrel might be installed and correctly headspaced by gauging, the worn lugs permit even more of the cartridge head to be unsupported beyond the chamber mouth, which is an unsafe condition. I've also found receivers with lug seats worn enough to permit the safety lug of a new bolt to contact the receiver - that is why Ordnance required a field test bolt be used to gauge receivers returned for rebuild, and scrapped any which failed gauging. To assemble a rifle with a severely worn receiver and bolt is asking for trouble, and no gunsmith who knows better should ever do such a thing - even though it may be possible to make it pass headspace gauging perfectly. No mechanical assembly will withstand infinite service and wear without accumulating stress and dimensional changes, and many of the remaining 1903 receivers and bolts have been used and abused far beyond what Ordnance would have permitted. Then, falling into the hands of less scrupulous commercial dealers, they have been re-finished, reassembled and sold to the unwary and unknowing - most of whom never experience any real trouble - through luck. Sooner or later, luck runs out. If you know better than to depend on it, you should tell those who don't yet know, but have the sense to ask the right questions, the facts they need. Then they can decide what to do without having to rely on their luck alone.
I used the term headspace with regard to the cartridge because the rifle must be adjusted to function safely with the permissible variations in cartridge length from the datum point to the head of the case, and, as that length is not fixed (as it cannot be in large-scale manufacture), wanted to explain why the cartridge case is not really a suitable substitute for a proper gauge.
And, finally, I try hard to respond to questions I know the answers to in the simplest terms, rather than responding with a core dump to demonstrate whatever else I know - however interesting such information may be to me, it doesn't really help clarify the original issue. And if more information is needed or wanted, the original questioner can ask for it.
mhb - Mike

[fguffey]

mhb, You do not owe me an explanation, I read your response, I read your rational, I understood everything you posted. You on the other hand are not under any obligation nor is there is demand on my part for you to make any attempt to ever try to understand what I said.

The first 20 bolts I pick up and installed as a replacement bolt will not change the length of the chamber from the shoulder to the bolt face .001”, if I needed a bolt that has an effect on the length of the chamber I could call and ask, if there was anyone that knew how to measure the bolts effect on the length of the chamber. That leaves me to driving to Irvine and or Grand Prairie with my measurements to compare measurements with two sources of bolts in the Dallas/FT, Worth area.

I understood the question, “Dangerous?” One more time, it does not have to be, ignorance is dangerous, ignorance is ‘not knowing’. Nothing drives me to the curb, nothing locks me up, just because the bolt closes the light does not have to go out. The bolt on an 03 will not close on a 280 Remington case, but! if it did ATTEMPT closing the bolt on a 280 Remington case I would know the chamber on the 03 is at least .046” longer than a 30/06 chamber. If I did chamber a 280 Remington case in a 30/06 chamber and the bolt lacked .046” CLOSING I WOULD KNOW THE 30/06 CHAMBER WAS GO-GAGE LENGTH.

Because I am a case former/reloader, with presses and dies, including forming dies, all with threads I can use a 280 Remington cases to form 30/06 cases, I know, with all the 30/06 cases around, why would anyone form 30/06 cases? Simple, I can form 15 cases with 15 different lengths from .000 (minimum case length) to +015” longer that a minimum length/full length sized case. Back to the coveted head space gages, they come in 3 sizes, first is the go-gage, .005” longer than the minimum length case, the no go-gage .004” longer than the go-gage (.009” longer than the minimum length case), then there is the field (reject) gage, it is .014” longer than the minimum length/full length sized case, .009” longer than the go-gage, .005” longer than the no go-gage. Then we go back to Hatcher, he moved the shoulder forward .070”, he had a difference in length between his chamber and case of .075”, mhb, if you are keeping up that is .060” beyond the field reject gage. DANGEROUS? Hatcher knew when he started the case could not stretch that far. Back to dangerous and not knowing. and ‘it does not have to be that way.

And the standard from a forum reads like this “Purchase extra bolts just in case the head space? (length of the chamber from the shoulder/datum to the bolt face) is not correct, AND there is a chance you can get lucky with one of the extra bolts”.

F. Guffey

[fguffey]

The man I purchased the mill from, he had a box of go, no and beyond gages, he took them out and handed them to me, and I ask????? “You know the bolt closes on the go-gage?” “You know the bolt will not close on the no go-gage?” “You want to know the length of the chamber in thousandths?” Again, the length of his chamber was .0075” longer than a minimum length case, he had a new, over the counter, unfired box of 20 Remington ammo, we checked the length of his new ammo from the shoulder to the head of the case, total spread .0005” and that ‘my friend? is better than his box of head space gages. Then to explain the box of gages, the man that gave them to him measured the gages and proclaimed “I can do better than that!”

Back to “driving me into the curb” A go-gage can be converted to a go to infinity-gage, but, there just does not seem to be anything beyond talking about it.

F. Guffey

[mhb]

fguffey:

What we have here is a failure to communicate.
I addressed you directly because you took exception to something I posted in clarification of one of the responses to the original question which started this thread.
I believe my answers to that original post were concise, accurate, and sufficient to satisfy the original poster's need for information, and that the added comments on the suggested ad-hoc headspace test were appropriate, also.
Having carefully re-read (again) all that you have contributed thusfar, I have to say that I can find no added value to the original discussion - neither can I determine what pertinent points (if any) you were trying to make. I believe there is no point in continuing this particular exchange.
And, FWIW, I do have a copy of Hatcher's Notebook - but none of Hatcher's experiments under controlled conditions can be taken as an indication of assured safety to the average shooter who controls few, if any, of the many variables in the arms and ammunition he uses.
If you still feel it necessary to continue with this thread, please address your remarks to one of the other posters: I have nothing further to add, and no interest in argument for its own sake.
mhb - Mike

[daveboy]

Interesting....

[Tom]

Hey guys, on my hunting rifles (1903A3) the bolts are nicely modified for the scopes. The bolts "origin and vintage" cannot be seen because of the handle change. They could even be pre 1918, I'll never know. I recheck the headspace now and then. It is always good with the go and no-go gauges. No worries??

FGuffey said that an 03 bolt has a different measurement on one of the lugs, than the same lug on an 03A3? I would like to determine the original bolt type, from this measurement, if you could explain how to go about this. Thanks Tom.

[mhb]

The 1903 and 1903A3 bolts...

are functionally interchangeable. The dimensional difference referred to is the clearance allowed between the safety lug and the rear receiver wall: in the 1903, the minimum permissible clearance is .004". The A3 bolts were manufactured to give a much larger clearance at the same point, but, in neither case should the safety lug ever contact the receiver wall - it is only intended to prevent the bolt from being blown rearward out of the receiver in the event both forward locking lugs fail (and does serve somewhat to steady and guide the bolt in its movement).
In addition, the A3 bolts are generally much more roughly machined, and have an area of visibly smaller diameter around the safety lug as a result of simplified machining, while 1903 bolt bodies are smooth for their full length.
If you have any doubts about the bolts in your rifles, some photos should allow them to be identified (roughly) as to original type, as would any markings remaining on the bolt handle root or safety lug.
mhb - Mike