30-6 Posted July 11, 2013 Report Share Posted July 11, 2013 Cutting a long story shortish, i finally got round to cleaning the rimfires lr and hmr for the first time. Lr zeroed back well with no bother. Hmr however was a problem. I fitted a new trigger spring (no shim) and it felt much nicer (i gave it a good test with a rubber mallet, scope off), but could not get better than a beer mat grouping at any range. After 137 rounds using a sand bag type rest on the bonnet of vehicle, i gave up and nearly run over it in frustration. Went home and put my thinking cap on. Thinking all i had done, i suspected diss-assembling the moderator (sak) could have the answer, and when i looked down the exit hole it had fouling with a definite streak where i assumed the bullet had been clipping. I put a rubber o-ring between the barrel and moderator, so when tightened it put the moderator 1/2 turn (180%) to where it originally tightened to. Re-zeroed and now grouping on the outside edge of a 25 mm bull at 100 yds. I have now put little white paint marks so the moderator will go back the same every time with the marks lining up to the top of the barrel. So, is it acceptable to "shim" a moderator, or do people open up the exit hole of the moderator ? Or what would others have done in that scenario ? Went out tried it in the field a day later. 1st rabbit 82 yds, 2nd 51 yds, 3rd 101 yds, 4th 76 yds, all aiming on. All head shot, off a tripod while standing. Also might add after reading on here about removing moderator while gun is in cabinet, i know do this as the end of the barrel is black with fouling (shows up as gun is CZ STYLE nickel plated). Please give me any views / opinions. CHEERS Quote Link to comment Share on other sites More sharing options...
fieldwanderer Posted July 12, 2013 Report Share Posted July 12, 2013 Was the bullet catching just the internals of the moderator? If so, I'd do away with the "0" ring and try to figure out what had changed inside the mod and how I could put it right. What you've done, I can't see it being a problem really except if the moderator gets knocked and doesn't return itself to central (because the rubber ring can obviously be squashed slightly which will allow the moderator to be pushed in any direction slightly which then puts it at an angle to the bore if you see what I mean) a metal washer would be better but I'd much rather fix the cause than the symptoms. Quote Link to comment Share on other sites More sharing options...
Underdog Posted July 12, 2013 Report Share Posted July 12, 2013 Sounds like the barrel is not threaded square! Is your cleaning rod straight? If so build it up with tape in two places and introduce it down the barrel and look for eccentricity at the moderaters muzzle. U. Quote Link to comment Share on other sites More sharing options...
Dekers Posted July 12, 2013 Report Share Posted July 12, 2013 (edited) :hmm: Perhaps I missed something, you stripped the mod and rebuilt it wrong, why didn't you just take it apart again, clean it and put it back together properly? Edited July 12, 2013 by Dekers Quote Link to comment Share on other sites More sharing options...
30-6 Posted July 12, 2013 Author Report Share Posted July 12, 2013 I think the bullet was only clipping the exit hole of the moderator, there was a triangular shape grey streak up the side of the exit hole, so not the internals. I only put the o-ring on because that's what i had to hand, like you say a solid spacer is better. The o-ring is 2.5mm thick and compresses to 2mm, so i have a friend making me a 2mm nylon spacer, which should tighten up ok. After watching many tutorials and topics on here, i used a bore guide, dewey rod and patches / nylon brush / shooters choice solvent, and a LOT OF CARE whilst in a gun cradle. I only dry brushed the moderator with a stiff nylon brush. I didn't re-build it wrong, not even i could put a sak back together incorrect. What i meant was when re-assembled the outer tube was not necessarily in exactly the same place to the baffles as when it came off. Now i have marked the different pieces so that when it comes apart again it will go back in the same position. So is adding a spacer ok, or open up the exit hole on the moderator or what ? Quote Link to comment Share on other sites More sharing options...
Beretta28g Posted July 12, 2013 Report Share Posted July 12, 2013 Hmm id be suspicious, and id be wanting to find the actual cause of this rather than botching a repair Quote Link to comment Share on other sites More sharing options...
al4x Posted July 12, 2013 Report Share Posted July 12, 2013 yup exactly if it worked fine before cleaning it is a problem somewhere, if its clipping the mod then that is not good at all and it needs looking at by someone who does know. Quote Link to comment Share on other sites More sharing options...
dadioles Posted July 12, 2013 Report Share Posted July 12, 2013 (edited) The sak moderator is pretty simple and I cannot see how you could take it apart, clean it, and then put it back together wrongly. Have you ever clumsily cross threaded it onto the barrel? Some people are more "sensitive" to this than others! The sak has a bore for .22 so there is extra clearance when used for .17 hmr. There should not be any possibility of clipping. In my view any attempt to "shim" a moderator is a recipe for disaster and should never be done, ever! You should be able to unscrew the moderator before the gun is stored in a cabinet and replace it without any issues of zero. It sounds to me as though you either have a badly threaded barrel or a faulty moderator and you need to get to the bottom of it quite urgently as the problem will not just go away. Try 5 shots at a target (50 yards will do) with the moderator removed (ear protection would be a good idea). That will at least prove that your rifle works accurately. Aim all five shots at the centre of the target, they will not be on zero and that does not matter. It is a tight group that we are looking for. They will be off zero because the balance of your rifle will have changed, no moderator means different barrel weight and harmonics. Also see if your barrel is still free floating as having removed it from the stock to change your trigger action it may be back in a slightly different place. The tension of the screws can also make a difference. This has nothing to do with clipping the moderator of course. Hopefully you will get tight groups with the moderator removed (at 50 yards off a bipod you should cover all 5 shots with a 1p coin). That leaves you to discuss the thread and moderator with whoever sold you the rifle. Edited July 12, 2013 by dadioles Quote Link to comment Share on other sites More sharing options...
Beretta28g Posted July 12, 2013 Report Share Posted July 12, 2013 I regularly remove my mods without a problem , are you sure all the threads were tight as that can cause problems if their not. Also did you leave any oil/cleaning products in there? Quote Link to comment Share on other sites More sharing options...
30-6 Posted July 12, 2013 Author Report Share Posted July 12, 2013 Yeah i did try un-moderated, it did seem better but still not good enough, but saying that the recoil did seem to make the gun jump. One thing i remember is when i had the .22lr and a silver finished sak both new, it screwed on easily, but when i had the .17hmr with another sak black finished both new, it screwed on very tight. When i pointed this out to the RFD, he said it was the "coating" on the threads of the moderator, it does seem free now though so perhaps he was right. What i think i need to do is try the silver sak off the lr on the hmr to see if all shoots well. Quote Link to comment Share on other sites More sharing options...
al4x Posted July 12, 2013 Report Share Posted July 12, 2013 slack threads would cause a problem Quote Link to comment Share on other sites More sharing options...
dadioles Posted July 12, 2013 Report Share Posted July 12, 2013 Yeah i did try un-moderated, it did seem better but still not good enough, but saying that the recoil did seem to make the gun jump. There is not a lot of recoil with an hmr. You should be getting very tight groups at 50 yards. If not, back to square one, check free floating barrel and all the other standard stuff, including different makes of ammunition, as something is not right. One thing i remember is when i had the .22lr and a silver finished sak both new, it screwed on easily, but when i had the .17hmr with another sak black finished both new, it screwed on very tight. When i pointed this out to the RFD, he said it was the "coating" on the threads of the moderator, it does seem free now though so perhaps he was right. Although that is plausible it does perhaps give a clue, badly threaded? cross threaded? how tight is "very tight"? If it feels "free" now it may be just that you have effectively cut new off-centre threads in a badly aligned sak. The sak is softer than the barrel so if this is what has happened you may be lucky and have a bad sak and an undamaged rifle. Can you not try the sak off the .22 as they are all the same? What i think i need to do is try the silver sak off the lr on the hmr to see if all shoots well. Yes, or at least see how it screws on. Never force a screw thread. Quote Link to comment Share on other sites More sharing options...
Dekers Posted July 12, 2013 Report Share Posted July 12, 2013 (edited) slack threads would cause a problem But if the barrel thread shoulder was true, and the mod screwed tight to it this should align it straight. It would have to be incredibly slack for this not to be the case. Something odd is going on here! Edited July 12, 2013 by Dekers Quote Link to comment Share on other sites More sharing options...
welshwarrior Posted July 12, 2013 Report Share Posted July 12, 2013 This does not sound right to me and I don't like the sound of shimming a mod. Try the other SAK but strip the black one to as you make spot something not quite right. Quote Link to comment Share on other sites More sharing options...
njc110381 Posted July 12, 2013 Report Share Posted July 12, 2013 I really can't see how you could get a Sak back together wrong? All the baffles are in one piece with the end cap is threaded to fit the barrel? I can't figure out how stripping it will change anything? If the mod was cross threaded at some point a rubber washer would not help alignment. If anything it would buffer any effect that the shoulder would have on straightening things up - I think that would make it worse? I think you've tightened the action screws badly when you put the gun back together. Check the free float of the barrel by running a piece of paper between the barrel and stock, and also re-check the screws. Also check the scope mounts as you've had them off too. Are they all tight and how they should be? Quote Link to comment Share on other sites More sharing options...
dadioles Posted July 12, 2013 Report Share Posted July 12, 2013 (edited) If (how certain are you?) your bullets are clipping the exit hole of the mod, bearing in mind the exit hole is .22 which leaves lots of clearance for .17, then either your mod is faulty or your barrel thread is faulty. Nothing else is relevant. Putting a washer or nylon spacer over the end of the barrel thread is a completely daft and dangerous idea, don't even consider it. As Dekers said, "if the barrel thread shoulder was true, and the mod screwed tight to it this should align it straight". Maybe you have misdiagnosed the problem and the bullet is not clipping the mod. If that is the case there are a whole load of basic checks for you to do. As I said, if the bullet is genuinely clipping the moderator you need professional advice from a good gunsmith as either your moderator is faulty or your barrel thread is out of true. It would not take much of a knock to distort the fitting. If you remove the bolt and look down the barrel with the mod fitted, does it all look straight? If you pass a cleaning rod through the barrel from the breech end and through the moderator does it all seem to line up? Edited July 12, 2013 by dadioles Quote Link to comment Share on other sites More sharing options...
shaun4860 Posted July 12, 2013 Report Share Posted July 12, 2013 All depends on which mod you want to shim, Zapp or Cranfield I would think are a no no Beardo and Dunkeld are up for it so i've heard Steve B is from Wales, make your own mind up Thats me on the norty step now methinx Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.