SLR L1A1 STRAIGHT PULL

[Gil Boyd]

I suppose it lies in a multitude of small overcomable issues. Don't forget of course the Belgium FN was manufactured using metric dimensions, while all the components of the "inch-pattern" UK FALs were manufactured to a slightly modified design using British imperial sizes. When I look at that original video by the SAC the weapon was brought in to fire .308, when they assumed that was to be the NATO round.
Yes I can relate to perhaps the BB not doing what it should, but I think the issue is two fold:
1. The selection of the right round for the barrel
2. The barrel itself and the alignment to a round being placed into an expanding non discript barrel on these straight pulls, and thats why after so many rounds, the heat transfer is magnified and "parts" expand, where a more efficient casing on a round would prevail.

Simply put, its a compatibility issue, when you see the progress of the straight pull in this country and the way some RFD's have tackled it, or is it the lack of gas inertia to overcome the initial unlocking of the bolt toggle from the locking shoulder, as they are not working as the original gas operated designs intended them to.

Am I addressing an issue we all have after a number of rounds going through the weapon as it is configured here as a Straight Pull?? A time lapse camera with the top cover removed would solve it as Peter L suggested!!!

[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!

[mrclark303]

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........

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

I do have the info on that meeting somewhere Gil and Peter, need to look it out ... The outcome of decision was to allow the first importer of these SP rifles (Anglo Custom) to go ahead and bring them in under Sec1 of the firearms act.

Until that point I believe it was not allowed, due in part to a small caveat placed within the 1988 Firearms amendment, designed to ensure people didn't find a way to circumvent the new laws and keep their AR15/L1A1/AK's etc by having them rendered Straight pull.

20 plus years after the fact, this was no longer an issue. Added to this, around the year 2000, Imbel Fals were imported in small numbers by Sabre Defence, built as straight pull rifles, the only thing they lack is a ported barrel!
Some of the first rifles even had pistons and springs fitted (most subsequently removed by RFD's over the years quite rightly), as this was part of the standard build, so the factory just fitted them.

Taking these Imbel rifles into account, it was realised that the L1A1 is effectively the same rifle, the HO therefore agreed to allow L1A1's to be built up, using modified original and new components, providing reasonable steps had been taken to ensure they couldn't be easily returned to a functioning semi automatic rifle.

Following on from this original Anglo Custom agreement, came Suffolk rifles, Tony (is that a police siren I hear) Buckland and a few others, last, but by no means least we have Gils new rifle, part of what I feel will be the last of the breed to be built up in the UK.

All the L1A1 SP builders went about modification to prevent conversion to Semi Automatic in different ways and barrels were either new, or "re-purposed" NOS barrels, with sufficient meat on them to machine to profile.

We have also seen SP M1 Carbines, Garands and M14's among others appear over the last 6 years or so, some all new build (M14 for instance) others using original parts kits.

Your comments on cycling single shot rendered L1A1's in for work without issue is very interesting Peter. Regarding military CHS, you are spot on, the Proof Houses require a different spec that in itself can cause some serous cycling issues too.

[Gil Boyd]

Some of those who did supply these from memory and keeping an eye on the thread over the years was:

Anglo Custom
Suffolk Rifles
Imbel
AR Buckland
Lufdeftech
Mervyn Young NI
Enfield Guns

Few other RFD's whose names escape me, probably long gone like a few on that list.

The below answer is what was given to Anglo Customs in the day no date I'm afraid unless someone else has it:

ANGLO CUSTOM L1A1

The Home Office has formally, through FELWG and ACPO, classed our
L1A1 SLR as unquestionably Section 1. The adaptations to the bolt and
carrier mean not only that it could not be converted to S5 use but that the
fact it was submitted for formal approval means all Police Authorities will
be informed as part of ACPO's guidance.