SLR L1A1 STRAIGHT PULL

[muffett.2008]

Well you can't blame it on gas

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[Gil Boyd]

Peter,
If you are baffled I am sure the rest of us are too.
Let me try these Winchester .308 145gn out on it, as I think its a round/case issue where the neck has been shimmed on the new barrels, could be wrong!

[Peter Laidler]

............the neck has been shimmed on the new barrels,

I don't understand that bit Gil. The first answer we/I need is as per thread 16

[skiprat]

When the Aussies made their single shot manually operated target L1A1's they positioned the new cocking handle on the back of the carrier (by the rat tail rivet).
The British straight pull use the original cocking handle position, putting pressure on one side at the front of the carrier.
With all the parts been used(and old) is the act of cocking imparting twist to the carrier adding extra friction?

Is the cartridge/chamber preventing easy extraction, or is it the carrier.
If I remember correctly (its been 30+years) the carrier should be free to move rearward for about 3mm before contacting the unlocking cams on the breach block, pulling UP on the breach block , so the rear of the carrier (where the cam surfaces are) is forced down, also as the cocking handle is pushing from the front of the carrier there will be some effort to rotate the carrier in it's rails adding even more friction.
If the cocking handle is at the rear top of the carrier (as the Aussies did) the cocking action would lift the rear of the carrier, reducing any rotation.

[Gil Boyd]

Could it be down to the bolt locking against the shoulder with the pressure and also sticking of the case in the chamber, with no gas force to help extract and unlock???
Ammo pressure and choice of ammo I submit is crucial.
With lower pressure cartridges such as the 7.62 x 39mm or .308 145 gr. Lets see when I next attend the range.

[mrclark303]

When the Aussies made their single shot manually operated target L1A1's they positioned the new cocking handle on the back of the carrier (by the rat tail rivet).
The British straight pull use the original cocking handle position, putting pressure on one side at the front of the carrier.
With all the parts been used(and old) is the act of cocking imparting twist to the carrier adding extra friction?

Is the cartridge/chamber preventing easy extraction, or is it the carrier.
If I remember correctly (its been 30+years) the carrier should be free to move rearward for about 3mm before contacting the unlocking cams on the breach block, pulling UP on the breach block , so the rear of the carrier (where the cam surfaces are) is forced down, also as the cocking handle is pushing from the front of the carrier there will be some effort to rotate the carrier in it's rails adding even more friction.
If the cocking handle is at the rear top of the carrier (as the Aussies did) the cocking action would lift the rear of the carrier, reducing any rotation.

Andy, excellent points, I know a chap who shoots one of the single shot Lithgow rifles in the US (pic of said rifle attached) and he doesn't report any issues.

At the end of the day, these rifles were designed to have a steel piston strike the top the carrier and with said 3mm of moment in the BC giving a suitable sharp pull on the BB to unstick the case.

Gil, you will I am sure find your rifle improves with use and chamber cleaning, I only get the very occasional issue with my two rifles now, mostly, they both shoot just fine if fed their preferred diet GGG.

The rubber mallet gathers dust in my range bag, I am glad to say...

[Peter Laidler]

Mmmmmm. I'm not sure that the position of the c/handle will have an adverse effect on the hard extraction issue Skippy, But owners COULD satisfy our curiosity by slightly rounding or putting a small radius on the rear RIGHT hand edge of the runner of the BBcarrier (the BBC). That would eliminate any tendency of the rear right side to jamb up caused by a tendency to rotate and therefore friction.
I am inclined to believe that it is a barrel issue. I say this because when we tested certain* rifles on the layer we fired them with the gas plug rotated so that there was no gas (or need for gas). And they worked just fine. The 'new' rifles with new-made barrels simply do not allow the BB to lift and while doing so, the top surface of the BB face rocks slightly, rotating about its fulcrum and let the extractor just tweak the case, loosen it and then........ THAT IS PRIMARY EXTRACTION. If you ain't got that, what follows is, er...... no extraction
What I need to know is this.......... Rifle will not extract or eject. Does the BBC move slightly rearwards or is that solid too? Are all the rifles to the UK MoD CHS spec. Or is this some dodgy proof house spec or some home builders spec or other enthusiastic amateur spec?

Clarkie, your thread 24, para2 is not really relevant because by the time the piston strikes the BBC, the bullet has left the barrel, the pressure has subsided to a safe level (there will be a bit of course but basic physics tells us that gas vents immediately). So what you are faced with is exactly what the piston is faced with when it imparts its energy.

* rifles that came in with non gas related problems or just accuracy testing were fired without gas. It saves cleaning afterwards.....

Oh, yes...., an afterthought. It would be a very simple matter to eliminate the cocking handle position querie. Just knock out the PIN, axis rod from the BBC and insert a short steel bar. Length of nylon cord around both sides of rod, fire rifle and pull rod and BBC rearwards. That is cycling the BB and BBC directly and centrally - as per the piston. If it is perfect, that's the problem and answer. If not, back to the drawing board but another querie answered and eliminated

[Gil Boyd]

Peter,
I am waiting for the ACPO guidelines on L1A1 Straight Pulls as issued a number of years ago, but I am certain they had to conform to a specified specification laid down to conform to be able to be sold as Section 1......anybody got a copy they can put up, and have I got that right?

[Peter Laidler]

I don't think that it was an ACPO matter Gil;. I believe that it was a HO decision based on the definition of 'assembling new component parts* into what is a new weapon'. The component parts that were the subject of this decision were the proofed or load bearing parts had to be either new or never having been used in, or formed part of a firearm in the UK in the past. That's because the law relates to within the UK and not anywhere else. More to it than that but............ Not an ACPO matter. No doubt they were hopping up and down like frogs on fire at the decision but there you go........

[Gil Boyd]

Peter,
Absolutely right, Home Office but through ACPO Firearms Committee to ensure Forces Licensing knew what they had coming in the day!