SMLE Key Holes on target today

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The_Champ

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I got a bit of a surprise when my SMLE began to key hole with factory ammo today. The culprit was PPU FMJ.

As best can recall I have shot S&B(FMJ & Soft Nose), PPU Soft Nose, Remington, and Winchester ammo through that rifle. All of it has show not the slightest hint of key holing.

Today with the PPU FMJ at 50 yards the bullets were full on travelling sideways.

I measured a few of the bullets and they are all the diameter they ought to be. Today is shot S&B FMJ fine.

I pulled one and laid it next to a S&B FMJ. The PPU certainly has a more exaggerated shape and less of the bullet would be engaged in the rifling.

Color me surprised.
 
Have you gone to a longer bullet or less velocity? Those factors are related to bullet stability too.

A bullet long enough to be a problem seems unlikely as milsurp stuff is usually longer than factory.

Have you slugged your bore? If it's oversized maybe you were getting lucky with the previous undersized bullets and these are a different construction that isn't as forgiving.
 
vagrantviking said:
Have you gone to a longer bullet or less velocity? Those factors are related to bullet stability too.

A bullet long enough to be a problem seems unlikely as milsurp stuff is usually longer than factory.

Have you slugged your bore? If it's oversized maybe you were getting lucky with the previous undersized bullets and these are a different construction that isn't as forgiving.
Click to expand...

As per their website stats, PPU and S&B FMJ rounds have almost identical velocity. Likewise when I pulled the bullets, length is nearly identical, but the boat tail on the PPU is more exaggerated.

Haven't slugged the bore, no.
 
I heard once that the SMLEs like the flat based bullets. Not sure if there is any truth to this as I haven't ever tested it but it's worth looking into.
 
but the boat tail on the PPU is more exaggerated.

THAT's your problem.

Go to a flatbase bullet and the keyholing likely will disappear.

Enfield rifling is 5 grooves, lands and grooves EQUAL width, DEEP grooves.... and it is 1 turn in 10 inches LEFT-hand. It demands a lot of sealing in a small space on the part of the bullet. That's the bad part. It is also the REASON that the Army stayed with a flatbase slug for rifle use for the entire period the LE was our front-line rifle. Boat-tails were made originally for EXTENDED RANGE fire with Vickers guns and were never intended for rifle use.

The GOOD part is that, using flatbase bullets, an Enfield-rifled barrel can run up to 22,000 rounds before it hits the "worn out" stage.... and that's with Cordite Mark I. Modern powders are cooler, so your barrel should last longer.

Also, it was found by actual test that, even though the BORE is .303" and the LANDS are .004", making the theoretical projectile diameter .311", accuracy was ALWAYS better with bullets to the UPPER limit of tolerance, which was .312".
 
smellie said:
but the boat tail on the PPU is more exaggerated.

THAT's your problem.

Go to a flatbase bullet and the keyholing likely will disappear.

Enfield rifling is 5 grooves, lands and grooves EQUAL width, DEEP grooves.... and it is 1 turn in 10 inches LEFT-hand. It demands a lot of sealing in a small space on the part of the bullet. That's the bad part. It is also the REASON that the Army stayed with a flatbase slug for rifle use for the entire period the LE was our front-line rifle. Boat-tails were made originally for EXTENDED RANGE fire with Vickers guns and were never intended for rifle use.

The GOOD part is that, using flatbase bullets, an Enfield-rifled barrel can run up to 22,000 rounds before it hits the "worn out" stage.... and that's with Cordite Mark I. Modern powders are cooler, so your barrel should last longer.

Also, it was found by actual test that, even though the BORE is .303" and the LANDS are .004", making the theoretical projectile diameter .311", accuracy was ALWAYS better with bullets to the UPPER limit of tolerance, which was .312".
Click to expand...

Thanks smellie. Always good to be reminded of the basics!
 
smellie said:
but the boat tail on the PPU is more exaggerated.

THAT's your problem.

Go to a flatbase bullet and the keyholing likely will disappear.

Enfield rifling is 5 grooves, lands and grooves EQUAL width, DEEP grooves.... and it is 1 turn in 10 inches LEFT-hand. It demands a lot of sealing in a small space on the part of the bullet. That's the bad part. It is also the REASON that the Army stayed with a flatbase slug for rifle use for the entire period the LE was our front-line rifle. Boat-tails were made originally for EXTENDED RANGE fire with Vickers guns and were never intended for rifle use.

The GOOD part is that, using flatbase bullets, an Enfield-rifled barrel can run up to 22,000 rounds before it hits the "worn out" stage.... and that's with Cordite Mark I. Modern powders are cooler, so your barrel should last longer.

Also, it was found by actual test that, even though the BORE is .303" and the LANDS are .004", making the theoretical projectile diameter .311", accuracy was ALWAYS better with bullets to the UPPER limit of tolerance, which was .312".
Click to expand...

Mine are all better with .312 than with .311 bullets.
 
Most ex-service rifles have digested a diet of mixed cordite and nitro ammunition.

Cordite burns very hot and is the cause for throat erosion.

As Mr. Smellie noted, boat tailed bullet loaded ammo was intended for use in machine guns.

A boat tailed bullet in a rifle with a worn throat (they all wear) will experience blow by and gas cutting of the throat which will exacerbate the problem.

A flat based bullet will obturate into the lead (pronounced leed) and into the rifling. ie the kick in the bullet's arse will make it swell to engage the rifling.

I rarely buy factory ammo, but when I do, I use it for plinking to get the empty brass, then I reload it to suit the individual rifle.
Each rifle will have a recipe with a sweet spot for bullet diameter, weight, powder and load. Hand loading is a hobby in itself.
What works well in one rifle might work like crap in another.

Seems you have discovered your rifle's preference in brand of ammo.
 
Last edited:
Newbie question here... Are both the No.1 and No. 4 equally prone to this tumbling of boat tail bullets? Or is this behaviour more typical of the No.1 rifles? Thanks in advance!
 
Now that is a very good question and opinions vary.

Provided that the No.1 is set up for Mk.VII ammunition, the barrel should in theory, behave much the same as any No.4 with regards to the conditions that make key holing. Bore and chamber dimensions are very much the same, same barrel length, but a different weight barrel. The rifling on a No.1 is five groove left. On a No.4 it can be 2 or 5 groove left hand twist or six groove right hand (I think).

Check behind the rear sight (or occasionally in front, or both) on your No.1 for markings stamped in tiny letters in the top of the barrel. HV for high velocity (sights calibrated for Mk.VII ammo) and SC for a short cone lead (for the pointed bullet).

I said in theory, but bear in mind that...... In theory, 'in practice and in theory' are the same. In practice, 'in theory and in practice' can be markedly different!
 
englishman_ca said:
Most ex-service rifles have digested a diet of mixed cordite and nitro ammunition.

Cordite burns very hot and is the cause for throat erosion.

As Mr. Smellie noted, boat tailed bullet loaded ammo was intended for use in machine guns.

A boat tailed bullet in a rifle with a worn throat (they all wear) will experience blow by and gas cutting of the throat which will exacerbate the problem.

A flat based bullet will obdurate into the lead (pronounced leed) and into the rifling. ie the kick in the bullet's arse will make it swell to engage the rifling.

I rarely buy factory ammo, but when I do, I use it for plinking to get the empty brass, then I reload it to suit the individual rifle.
Each rifle will have a recipe with a sweet spot for bullet diameter, weight, powder and load. Hand loading is a hobby in itself.
What works well in one rifle might work like crap in another.

Seems you have discovered your rifle's preference in brand of ammo.
Click to expand...

Thanks for a very informative post...!
 
Thanks x2! One learns new things everyday.

Edit:
I have a No. 4 Maltby 1944 (FTR 1954) that shoots the S&B FMJ rather well. I now need to pull one bullet to confirm whether the base is flat or boat-tailed...
 
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