Shooters Forum banner

Tuning a rebuilt SMLE #1 Mk 3

4776 Views 19 Replies 9 Participants Last post by  gunho1954
I recently had a SMLE #1 Mk3 rebuilt. The rifle is a bit of a blitzer with parts ranging from 1915 on up to the 20's. The barrel is from the 50s and was still in the grease when I bought it. I am currently looking for any info on armorers State-side that know this rifle. My gunsmith did an excellent job getting the rifle put back together, but I am questioning the head space on it. He doesn't work on 303s and probably only did what he did since I am a friend of his son.

When I finally got it to the range, the first shot was with Remington factory loads and I had total case separation. After clearing the broken shell I returned to the range with handloads I worked up (174gr Woodleigh on top of IMR 4064 @ 4 different weights & 215 gr Woodleigh on top of 35 grs of IMR 4064). The rifle fired without breaking any shells, but all but one had high primers and a few pierced primers. Granted these were all unfired Winchester brass.

I just want to find somebody that knows these guns well enough to give it a once over before I sink the money into the headspace gauges & firing pin gauge to check it myself.

1 - 3 of 20 Posts
If memory serves that rifle used something like five different bolt heads of different length to achieve the correct headspacing. Suspect you would need to measure the distance between breach face and bolt head then order the correct bolt head length required for headspace.. Likely would have too locate a source for those bolt heads--possibly Numrich Arms.
Good advice!

This is still .303Brit, right? Make your own headspace guage: cut a small piece of soda can into 3 disks the diameter of the case rim. Now try one stuck on a sized case - you can use grease to hold it in place while you attempt to close the bolt. Now try two at once, then three at once while you attempt to close the bolt. Each shim is approximately .004" thick, so you can tell "how far off" the headspace is by adding shims until the bolt is difficult to close. My No.4MkI will barely close on one shim.

Also, since you reload, you can custom-size your brass to alleviate headspace by partial sizing as follows:

1. Expand the necks of new brass to 8mm or so.
2. Back your sizing die out at least one full turn.
3. Size a case & try in your rifle.
4. When the case will chamber, screw die in an additional 1/8th turn and lock it down.

I notice you're using premium bullets - I'd recommend cast bullets to fire-form cases, or lighter loads using bulk bullets like Remingtons. Also if it fails the "three-shim-test" by easily closing - straight to a gunsmith!
See less See more
the headspace system is fine on a mauser,but on a 303 the extractor groove is cut to the shoulder specs.if you turn .005 to 008" off the shoulder,to effect headspace,your groove will not line up--hence the a,b.c.d.bolt heads on a 303 as cited by"hailstone"who was all ready on to it. hope this helps.this is not the only way to get correct headspace.
I never said "turn off" anything. Please read my post before replying to a "headspace-check" post with a "barrel setback & timing" post. Thank you.
This is the point I was trying to make. Fireforming a case in a rifle of this type with excessive headspace does nothing to solve the headspace problem. The originator of this thread had a factory round let go in his rifle. That tells me there is a serious headspace problem that should be seen to before shooting it again.


I agree - that's why he needs to know how far off headspace is. As I said - "if it fails the 3-shims check" - straight to the gunsmith!

I'm thinking it'll fail the test. But section some solid-webbed brass sometime and see just how far up from the rim the solid part is. Divide that distance in half & that's how far a straight case can be "formed to fit." A tapered case like the Brit? Maybe 1/3rd that depth. I personally like to stay within 1/4 or less, i.e. "3 soda-can-shims" or less.

Ya'll do what you want. And "when in doubt - go to a reputable 'smith!"
1 - 3 of 20 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.