Barrel cleaning versus accuracy

[ColinR]

Different problem here. I was at Orion shooting an AI AW 7.62 a few weeks back. Started shooting handloads that group to <.5 of an MOA at 100yards and everything was working well. Then shot 20 or so Malaysian tracers, which although high at 740 yards compared to the 170 grain Lockbase were spot on for windage. I then went back to the handloads and they were all over the place. Checked tightness of scope mounts and moderator, all tight. Tried to zero at 100yards and some shots were off the card. Suspected something was wrong with the scope, so checked it with a collimator and wound the scope up and down, left to right and it returned to the starting position (S & B PMll 5 - 25) Therefore assumed nothing wrong with the scope. Gave up for another day. I have cleaned it to within an inch of its life with CR2 and will try again when I next go to Orion later this month. I have another PMll which I will try but I feel this is not a scope problem. I am wondering if a baffle has come loose in the moderator an ASE Utra, so will try with a muzzle brake instead. I cannot believe the barrel has shot out during this session - its had only about 3.5K through it and I guess its got to be good for 7 - 8K. Otherwise at a complete loss as to this accuracy problem. Do the Tracers leave any nasty residue - the bullets are sealed with a pitch like compound - which could cause this complete loss of accuracy?

[snayperskaya]

Different problem here. I was at Orion shooting an AI AW 7.62 a few weeks back. Started shooting handloads that group to <.5 of an MOA at 100yards and everything was working well. Then shot 20 or so Malaysian tracers, which although high at 740 yards compared to the 170 grain Lockbase were spot on for windage. I then went back to the handloads and they were all over the place. Checked tightness of scope mounts and moderator, all tight. Tried to zero at 100yards and some shots were off the card. Suspected something was wrong with the scope, so checked it with a collimator and wound the scope up and down, left to right and it returned to the starting position (S & B PMll 5 - 25) Therefore assumed nothing wrong with the scope. Gave up for another day. I have cleaned it to within an inch of its life with CR2 and will try again when I next go to Orion later this month. I have another PMll which I will try but I feel this is not a scope problem. I am wondering if a baffle has come loose in the moderator an ASE Utra, so will try with a muzzle brake instead. I cannot believe the barrel has shot out during this session - its had only about 3.5K through it and I guess its got to be good for 7 - 8K. Otherwise at a complete loss as to this accuracy problem. Do the Tracers leave any nasty residue - the bullets are sealed with a pitch like compound - which could cause this complete loss of accuracy?

Just a thought but have you checked the action screws, if they have come loose that would cause problems accuracy-wise.If you are normally getting <.5 MOA then it's nowhere near shot out and certainly not as a result of a handful of tracer.

I've shot 54r tracer out of the Dragunov at Sennybridge and the barrel has been no dirtier with the tracer than it is with standard light ball.....then again the tracer I have doesn't ignite until it gets 80-100m out, is that the same with the 7.62x51 tracer you were using?.

[ovenpaa]

The AW is bonded and screwed to the chassis so I very much doubt that is the problem. I would say give it a very good cleaning and go back to your standard 170LB load and see how it performs with and without the sound moderator.

[ColinR]

[quote="snayperskaya]"[/quote
Just a thought but have you checked the action screws, if they have come loose that would cause problems accuracy-wise.If you are normally getting <.5 MOA then it's nowhere near shot out and certainly not as a result of a handful of tracer.

I've shot 54r tracer out of the Dragunov at Sennybridge and the barrel has been no dirtier with the tracer than it is with standard light ball.....then again the tracer I have doesn't ignite until it gets 80-100m out, is that the same with the 7.62x51 tracer you were using?.[/quote]

These are the tracer you very kindly identified for me a few months ago from the headstamp as being of Malaysian origin. They light up with a red trace at around 3-400 yards, so aren't burning in the barrel. Good point re: action screws. I now need to check if the plastic side plate screws on the AI are set to a torque value and if so to what before removing (Ovenpaa help) likewise the action screws. Thanks for the advice.

[ovenpaa]

Colin, the side plates (Skins) screws are M4 from memory and are purely to keep the crap out of the insides and make it look like a rifle... Inside is a 1" Box section chassis that is welded together. Do not attempt to check/remove or adjust the action screws unless the receiver is flopping around relative to the chassis (Doubtful at best, I have never, ever come across an AW receiver that was loose) If they are loose get on to Sporting Services or Accuracy International who will advise you accordingly.

From memory the chassis skins screw torque is 1.5Nm so do not over tighten them. You may find evidence of rust, this is normal as they are carbon steel. I have swapped out a couple to A4 stainless in the past however they are a bright finish.

[ColinR]

Colin, the side plates (Skins) screws are M4 from memory and are purely to keep the crap out of the insides and make it look like a rifle... Inside is a 1" Box section chassis that is welded together. Do not attempt to check/remove or adjust the action screws unless the receiver is flopping around relative to the chassis (Doubtful at best, I have never, ever come across an AW receiver that was loose) If they are loose get on to Sporting Services or Accuracy International who will advise you accordingly.

From memory the chassis skins screw torque is 1.5Nm so do not over tighten them. You may find evidence of rust, this is normal as they are carbon steel. I have swapped out a couple to A4 stainless in the past however they are a bright finish.

David, Firstly sorry for hijacking your post, not intended; just relating what might be another cleaning/accuracy problem. Needless to say I am very grateful to you for sharing your knowledge so generously. I will try all the other options before investigating the action integrity. As you say this is an unlikely cause and given the rifle was shooting fine previously I am sure any deterioration in accuracy would have been noticed earlier. It is clearly one of the following: barrel fouling, loose baffle in Moderator, some disconnect in the scope, barrel. Unfortunately I did not eliminate all of these on the last outing - it was raining and I was getting annoyed, so discretion being the better part of valour I gave up and resorted to the .338 lm which I am learning to love. I have reduced the charge of N165 from 88.5 grains to 86 grains behind the 250 grain Lockbase and it has become a different animal. Surprisingly I find the recoil softer with the muzzle brake than with the moderator, but it never was that much of a problem with such a heavy bit of kit. I am at Orion in a couple of weeks so I will give the AI AW 7.62 a complete shake down and hopefully come up with a solution. Thanks again, Colin

[snayperskaya]

The AW is bonded and screwed to the chassis so I very much doubt that is the problem. I would say give it a very good cleaning and go back to your standard 170LB load and see how it performs with and without the sound moderator.

Ah I see, these modern chassis systems are a mystery to me

So if they are bonded is it a major job to remove the action from the stock?.

[DOGGER2UK]

The action is permanently bonded to the chassis with epoxy(white line) and 4 bolts. As Ovenpaa said the bolt on sides are there to give you something to hold on to.

[ovenpaa]

David, Firstly sorry for hijacking your post, not intended; just relating what might be another cleaning/accuracy problem.

Not a problem, it is an interesting hijack

The AW is bonded and screwed to the chassis so I very much doubt that is the problem. I would say give it a very good cleaning and go back to your standard 170LB load and see how it performs with and without the sound moderator.

Ah I see, these modern chassis systems are a mystery to me

So if they are bonded is it a major job to remove the action from the stock?.

The receiver sits on four spacer washers/shims designed to maintain a precise gap between the receiver base and the chassis. The gap is filled with an industrial adhesive and the two parts can be separated with some heat. To assemble in simple terms clean the surfaces, replace the shims and screws and apply new adhesive and torque to the required setting. The sequence and procedure is detailed in the armourers notes.

The earlier AW and AE Chassis were fully welded however the later chassis do have some parts pinned and bonded such as the rear vertical that supports the butt pad.

[Swamp Donkey]

Different problem here. I was at Orion shooting an AI AW 7.62 a few weeks back. Started shooting handloads that group to <.5 of an MOA at 100yards and everything was working well. Then shot 20 or so Malaysian tracers, which although high at 740 yards compared to the 170 grain Lockbase were spot on for windage. I then went back to the handloads and they were all over the place. Checked tightness of scope mounts and moderator, all tight. Tried to zero at 100yards and some shots were off the card. Suspected something was wrong with the scope, so checked it with a collimator and wound the scope up and down, left to right and it returned to the starting position (S & B PMll 5 - 25) Therefore assumed nothing wrong with the scope. Gave up for another day. I have cleaned it to within an inch of its life with CR2 and will try again when I next go to Orion later this month. I have another PMll which I will try but I feel this is not a scope problem. I am wondering if a baffle has come loose in the moderator an ASE Utra, so will try with a muzzle brake instead. I cannot believe the barrel has shot out during this session - its had only about 3.5K through it and I guess its got to be good for 7 - 8K. Otherwise at a complete loss as to this accuracy problem. Do the Tracers leave any nasty residue - the bullets are sealed with a pitch like compound - which could cause this complete loss of accuracy?

So, let me get this right, it shot fine, then you put some nasty tracer through, that have a filthy bituminous sealant, then immediately afterwards, it shot like s*** ?

The only thing that changed was the ammo.

That you know has a nasty dirty bituminous type sealant, that goes down the barrel, that now won't shoot well, because its crudded up with bitumen.

Tracer is supposed to be for machine gun use, where accurate fire is a disadvantage, preferring a larger cone of fire for better suppressive fire, so nobody would generally give two hoots if it caused groups to open up, if they even noticed that it was happening.

Clean it. Its the only logical answer, nothing else would have made that difference that rapidly.

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