rich1985 Posted September 2, 2015 Report Share Posted September 2, 2015 Any one have any ideas as to why my HMR grouping is getting worse and worse. When I first got it and for a good few years after I could put the bullet holes touching at 100 yards and now the group is about 3.5 inch at 100 yards, I have fired about 10 to 12 thousands rounds through it. I thought it could be ammo so I gave a box to a mate and all was fine. Thanks Quote Link to comment Share on other sites More sharing options...
malkiserow Posted September 2, 2015 Report Share Posted September 2, 2015 Shot out maybe? Have you had a good look at the bore? maybe use a bore-scope if possible Quote Link to comment Share on other sites More sharing options...
ozzy518 Posted September 2, 2015 Report Share Posted September 2, 2015 As above but also check your moderator if you have one fitted. Mates rifle threw rounds all over the place. He had a collapsed baffle Quote Link to comment Share on other sites More sharing options...
Mutiny Posted September 2, 2015 Report Share Posted September 2, 2015 Have you cleaned it? Quote Link to comment Share on other sites More sharing options...
kent Posted September 2, 2015 Report Share Posted September 2, 2015 Either thr bore needs attention via a real good clean or the barrel is eroded or corroded Therr is also yhe possibilty of bolt faults or need for servicing Quote Link to comment Share on other sites More sharing options...
rich1985 Posted September 2, 2015 Author Report Share Posted September 2, 2015 Yeah I have cleaned it, stripped it right down, I did wonder about moderator being at fault, I will take it off and have a shot with it, if I can't get it sorted there's only 1 thing for it I will have to buy a new 1. Quote Link to comment Share on other sites More sharing options...
Underdog Posted September 2, 2015 Report Share Posted September 2, 2015 Have you a tendency to leave the mod on? Quote Link to comment Share on other sites More sharing options...
billytheghillie Posted September 2, 2015 Report Share Posted September 2, 2015 Have you a tendency to leave the mod on? Do you store your guns with mod off? and if so why? Quote Link to comment Share on other sites More sharing options...
MrDaveO84 Posted September 2, 2015 Report Share Posted September 2, 2015 As soon as I've finished shooting I take the mods off my rifles and always store them separately. Not sure of the exact chemistry but something in the burnt powder can react in the mod to make water vapour. So if you leave the mod on your rifle your effectively letting water drip down the barrel and on the crown which is not good Quote Link to comment Share on other sites More sharing options...
billytheghillie Posted September 2, 2015 Report Share Posted September 2, 2015 Thanks for reply, MrDave. Quote Link to comment Share on other sites More sharing options...
MrDaveO84 Posted September 2, 2015 Report Share Posted September 2, 2015 No worries mate, can't remember where I read that. I've talked to gunsmiths though who have had to remove moderators which have been left on rifles and effectively rusted together. Quote Link to comment Share on other sites More sharing options...
Vince Green Posted September 2, 2015 Report Share Posted September 2, 2015 You say you have cleaned it but how have you cleaned it? with copper remover? Quote Link to comment Share on other sites More sharing options...
kennett Posted September 2, 2015 Report Share Posted September 2, 2015 I'm a heathen, and even I take the mod off my hmr when I put it away, as said it is something to do with water vapour and "stuff" eating the Crown. Quote Link to comment Share on other sites More sharing options...
henry931 Posted September 2, 2015 Report Share Posted September 2, 2015 Try a copper and possibly a carbon remover - bore tech do specific ones If you leave the mod on then yeah, the last few inches of rifling are probably screwed In that case maybe the barrel can be shortened to get to some better rifling Or new barrel (is it worth it/possible on a hmr?) or rifle Quote Link to comment Share on other sites More sharing options...
Underdog Posted September 2, 2015 Report Share Posted September 2, 2015 During combustion, pretty much any combustion, water is produced. Yes the elements that make water are present in the propellent that drives your bullets. The rapid expansion in a cold moderator encourages this vapour to instantly condense on the interior surfaces. Eventually this finds its way to the crown. A damaged crown will give poor grouping. This is the chief reason I don't use mods on non lubricated bullet rifles like the hmr. Hornet is especially bad for leaving water vapour in the bore without a mod on! One single most preventative measure if one is not going to remove their mod every time is an oiled patch on returning home followed by a dry one just before leaving home next time out. Quote Link to comment Share on other sites More sharing options...
henry931 Posted September 2, 2015 Report Share Posted September 2, 2015 All I know is I sniffed the threaded end of a mod once, after I took it off a 223 that had just been fired, and am never doing it again Quote Link to comment Share on other sites More sharing options...
kory1986 Posted September 3, 2015 Report Share Posted September 3, 2015 (edited) Any one have any ideas as to why my HMR grouping is getting worse and worse. When I first got it and for a good few years after I could put the bullet holes touching at 100 yards and now the group is about 3.5 inch at 100 yards, I have fired about 10 to 12 thousands rounds through it. I thought it could be ammo so I gave a box to a mate and all was fine. Thanks Are you using the same optic try a different optic it may be the sight at fault not the rifle try a different one I had seen it many times before when blokes grouping starts getting massive a lot of the time it's the optic that's damage not the rifle Edited September 3, 2015 by kory1986 Quote Link to comment Share on other sites More sharing options...
Savhmr Posted September 3, 2015 Report Share Posted September 3, 2015 During combustion, pretty much any combustion, water is produced. Yes the elements that make water are present in the propellent that drives your bullets. The rapid expansion in a cold moderator encourages this vapour to instantly condense on the interior surfaces. Eventually this finds its way to the crown. A damaged crown will give poor grouping. This is the chief reason I don't use mods on non lubricated bullet rifles like the hmr. Hornet is especially bad for leaving water vapour in the bore without a mod on! One single most preventative measure if one is not going to remove their mod every time is an oiled patch on returning home followed by a dry one just before leaving home next time out. I usually clean the rifle after every outing with a gun-mouse (all nylon version of a bore snake), dry patch and light oil, then return the mod after shaking it out to get rid of any loose crud and fouling. The barrel and crown are still 100% fine 6 years later so this is a bit of a non issue I reckon unless people never clean or look after their bores. It most certainly could be an issue for someone who never touches their cleaning kits though! Quote Link to comment Share on other sites More sharing options...
Underdog Posted September 3, 2015 Report Share Posted September 3, 2015 I usually clean the rifle after every outing with a gun-mouse (all nylon version of a bore snake), dry patch and light oil, then return the mod after shaking it out to get rid of any loose crud and fouling. The barrel and crown are still 100% fine 6 years later so this is a bit of a non issue I reckon unless people never clean or look after their bores. It most certainly could be an issue for someone who never touches their cleaning kits though! Spot on mate Quote Link to comment Share on other sites More sharing options...
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