1903 and 1903A3 barrel identification and interchangeability

[Rusty.303]

G'Day all,
I am little confused about a 1903rifle I own, whilst trying to find out a bit about this rifle it has been mentioned that it has a 1903A3 barrel on it.
Can someone with more experience please help confused me.
What are the differences between 1903 and 1903A3 barrels?
Can a 1903A3 barrel be modified to suit a 1903 and is this a common fix?
The barrel is marked behind the rear sight RA 5/44, under this it is marked P and just in front of the rear sight collar it is marked XA72.
Thanks

Information

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[Mike D]

Seen it done before. Not common. Question is, has it been properly done? I think I have heard that the A3 barrel is a little larger round where it meets the receiver, and would have to be turned down for the fixed rear sight base to fit. The FRSB was pinned in two seperate locations. Not easily done.

[Kirk]

Are you saying a A3 barrel has already been mounted on your 1903 receiver, that a M1903 fixed base for rear sight plus a front sight have been installed? As Mike D mentioned, this has been done but not commonly. The key thing is that it has been properly mounted and that it head spaces OK. Functionally, the two types are identical.

[Rusty.303]

G,Day Kirk
I am unsure if the rifle has an 03 or 03A3 barrel fitted, the rifle has the 03 front and rear sight.
I ask the questions to try and identify what I have as I do not have a clue.
What is the go with the two pins mentioned in relation to the 03 rear sight collar.
I can identify the cross pin, where is the second pin?, is it used to index the sight collar to barrel.
Apart from the 03 sight collar do the 03 and 03A3 barrels maintain the same profile, I ask this as I should be able to notice any funny business where the barrel profile meets the front of the rear sight collar.
Thanks again

[Calif-Steve]

This was not done by the US Army. Strictly a recent job. A good gunsmith can do this conversion. But not USGI at all.

[Mike D]

To get technical, the FRSB has a base pin and a base spline. The base pin prevents longitudinal (forward and back) movement. It is located at the front of the FRSB on all but very early rifles (Blue arrow). The FRSB was pressed on, pinned, pin ground flush, then parked or blued. This makes the location sometimes hard to see.

The "undercut" (Red arrow) is used to index the FRSB to the barrel, and then the barrel assembly to the receiver. Think I got that right?

The base spline (Green arrow) prevents the base from turning on the barrel. A hole is drilled between the barrel and base and can't be seen with the barrel installed on the receiver. It is usually in the 1 o'clock position, though sometimes at 11.

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[e7insalemva]

Hi Rusty:
I'm a little familar with Springfields. What name is on your receiver? Remington turned out several thousand 1903's on Springfield's machinery when they took over from them and stamped
"Remington" on both the receivers and barrels, as well as other parts. The original Springfields had both front and rear sights on the barrels. If you have an original Springfield, check the
serial number to see if it is above 800,000. Rifles manufactured below that serial number are supposed to be dangerous to fire due to brittle receivers and bolts. The 03A3 Springfields have
rear sights mounted at rear of receiver. Hope this helps some........

[Rusty.303]

G'Day and thanks to both Mike D and e7insalemva for the reply.
The rifle concerned is a Rock Island Arsenal, Ser 382136, the barrel is marked RA 5/44 P and XA72, the bolt is marked R and the rear sight parts are marked R.
Here are a couple of pictures of what I have,
Thankyou

[Chuckindenver]

1903 barrels were all 4 groove. and contured for a rear sight base to fit tightly.
1903A3 barrels came both 2 , 4 and 6 groove, most had a heavey conture in the chamber area so that a rear sight base wont slid over.
early Remington A3 barrrels will have the rear sight base conture..until Feb 1943 i belive was a cutoff...
A3 barrels will be marked RA {Remington} SC smith Corona, and have WW2 dates, and have a different type of front sight base.
can it be done? sure...but why?
look at it this way.
a new A3 barrel will still set you back 150.00 plus, then you have to pay a good gunsmith to turn the barrel down to fit the rear sight base, and refit the front base,
then pay to have the barrel installed, and hope it indexes correctly, as you will loose the witness mark when the barrel is turned down.
so youll have more then 300.00 invested in a wrong barrel that may or maynot shoot well, and it wont be the correct barrel for the rifle.
if a guy is patiant, you can find a good new or used 03 barrel complete with a rear sight base for 200.00
youll still have close to 300.00 in the job, but at least it will be done right with the right parts...
anything worth doing, is worth taking your time, and doing it right.
pictured barrel is a replacement 2 groove, Remington 1903A3 barrel, that was installed by someone other then the military,,,, notice the nice black paintjob to cover boo boos