L8 and Sterling/Charnwood 7.62 conversions- Harmonics and Mathematics

[tbonesmith]

Have you looked at "The ladder method" of load development. Fast and effective. Google it.

[villiers]

Also worth remembering is that the Sterling conversions were never a military option and never trialled at any stage either, As for the Charnwood conversions, well................................... The least said the better but somewhere in the world there might be one with a happy owner

Me? My Charnwood No. 5 in .308 (in the right hands ... certainly not mine) is very accurate indeed. Although (I´m shamed to admit) it´s been Acraglassed. But like my other No. 5 in .303, it seems to be a lot better at 300 metres that at 100.

[Rusty.303]

I have owned two No4 .308 conversions,
The first rifle is a Savage with the Sterling .308 conversion and what I believe to be a standard profile barrel.
The second rifle is a Longbranch with a Lithgow .308 conversion and a heavy barrel.
I am not an expert on the different bedding techniques, however both these rifles appear to be floating for at least the front half of the barrel.
Both these rifles shoot very mediocre with mild loads.
I wish this wasn't the case however as the load gets to the point where it's hot both of these rifles shoot with much greater accuracy.
Cheers

[enscien]

Re the Sterling barrel, an example I checked some years ago (about 40!) had bore diameter 0.298" and groove diameter .3092 to .3095" by slugging (a bit on the high side). 6 groove rifling with a 1 in 12" twist.
I believe that some research was carried out at the Royal Military College of Science, Shrivenham 40 years or so ago on barrel vibrations and people would certainly have looked at improving the accuracy of the Sterling/L8 barrels by adjusting the bedding: it is a matter of tracking down the trial reports.

[xa-coupe]

Have you looked at "The ladder method" of load development. Fast and effective. Google it.

I have done a search and understand the principle.. have you used it? If it really works as easy as it sounds it will save heaps of time and ammo to my usual method of taking heaps of rounds to decide if a powder/projectile combo is any good or not.

[Longshaor]

Perhaps this is just the engineer in me, but given that there's a mathematical formula for determining barrel harmonics, is there a comparable formula for round harmonics?

[Mk VII]

The one I had was a twist rate of about 1:10.5, and it would not shoot M80 ball equivalent worth a damn. Only with reloads with a 180/190gn bullet did the groups shrink dramatically. This was with Fulton's 'New Zealand' bedding, as I recall.

[Peter Laidler]

The thing I learned about bullets and the associated harmonics is that whatever happens thereafter to the bullet, it's first exposure to the outside world (or life outside the case), even before it hits the atmosphere, is travelling up the vibrating bore of the rifle, accellerating (and not even at a steady or constant rate either.....) as it does so. That barrel, what it does and the way it moves dictates everything the bullet does. Not an scienmtifically EXACT statement I agree, but one at the forefront of how Armourers, as opposed to ballisticians think

[newcastle]

Question here. Why were the DCRA barrels so accurate then? were they a different profile from the 303 barrels? my DCRa without any special bedding is very accurate and to all intents and pruposes looks identical to a 303 apart from the lack of bayonet lugs.

[Thunderbox]

Question here. Why were the DCRA barrels so accurate then? were they a different profile from the 303 barrels? my DCRa without any special bedding is very accurate and to all intents and pruposes looks identical to a 303 apart from the lack of bayonet lugs.

Isn't your DCRA centre-bedded or free-floated?