Zeroing a moderated rifle

Steve29

Well-Known Member
How do you guys go about zeroing/target practice with a moderated full bore rifle? I've always zeroed by rattling off three shots in succession, checking the group and adjusting accordingly before firing another three. Well I did that last weekend and couldn't get a tight group, each succesive shot was higher than the last.

I've read that the temperature of the barrel and mod can make a noticeable difference to zero, and my 270 gets incredibly hot after three shots. So I've been thinking that the next time I go to the range i'll fire one round, put it to one side for a few minutes to cool down, rattle off a few mags on the .22 to keep me occupied, and then squeeze another one off the .270. Does that seem sensible, or is there something better I could try? Seems to me that the zero with a cold barrel is the most important as it'll most likely be cold when fired in the field.
 
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What you propose is spot on. Also remember to Zero with the rifle as it is when you go stalking and also try and shoot it as close to your preferred shooting style as possible but att he ssame time get you body - particularly your elbows well supported.
 
Thanks, that's useful advice, although I shoot at a tube range so can't shoot prone or standing as I would when stalking, I have to sit on a chair. It's good and stable though, and removes the weather factor which helps.
 
I always think when checking my zero before stalking is a bit false, only in the sense that the style of shooting at deer or foxes will always be different than target practice.

So this is what i do, I get my rifle set up as if i was stalking with mod and bipod on, set my target out to 100 mtrs, (obviously if this was the first time i had zeroed the rifle then i would start out at 50mtrs just to get me on the paper) and lay down and using the bipod, shoot a couple of rounds into the target. I go over and check out where they are and if they are anywhere near the bull i pack up and go home. You may think this is a little unusual, but the way i see it is this, if that had been a deer or fox, then both my shots would have killed it as it is always the first shots that matter. I always think too that if you start shooting more off, unless your a reloader then the chaces are you will get a flyer which then causes you to start questioning your ability as well as the bullets and rifle.

Some may disagree, but it works for me.;)

wadas
 
I zero with mod off if its gonna take a few shots, then let barrel cool down completely, slap cold mod on and then fire a three shot group with cooling in between to confirm mod on zero. I suppose I may be lucky as I have found my .308 and .243 shoot to the same poa with or without mod on a 100 mts.

Leon
 
I like to practise a fair bit using different rests/holds/positions etc to mimic "real life" stalking. I don't worry too much about group size but concentrate more on bullet strike(as per wadashot) as this is what matters. I would be concerned if bullets wandered way off the mark when the barrel/mod gets hot but an inch or two here and there is not the end of the world. By all means let your gun cool between shots to get best performance but plenty of practise in different conditions will really pay off in the long run.

regards
 
Steve,

Sounds to me like your barrel is touching the fore end of the stock with the moderator on. Could be that the extra weight is causing the lift. It is all to do with the heat and barrel harmonics. A bipod will only make it worse.

what king of stick is it? Run a tenner (or if you are english a fiver) up the barrel to the reciever if you can. If not it has forend pressure or touching somewhere.

I know some are not into free floating but moderators are new and it helped mine big style. The rifle used to drive me mad and I got it sub MOA after a few modifications the main one being free floating.

Hope this helps.
 
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Would have to agree with the last, Your moderator if fitted correctly should not make any significant difference if you rifle is in zero without a mod. The moderator has clearance so that when fitted correctly the bullet should not come into contact with anything inside it, it should essentially sail straight through regardless. The other thing if you have an overbarrel mod, is that it also has to be fitted so that it doesent foul at the backend of the mod with the barrel. When screwing an overbarrel on, if the mod seems to get 'tight; at one point of a rotation, then the mod and the barrel are coming into contact and it is not fitted correctly.

Was speaking to an excellent custom rifle maker at the weekend and he said that personally he wouldnt even trust a brand new 'screw cut' barrel that has been done in factory, always get it checked.

Just a thought.
 
I've found with my moderated Sauer 202 .308 that zero is spot on for about three or four shots, then starts to shift upwards as the barrel warms up. I let it cool for a few minutes and it's fine. Caused me no end of headaches when I was first zeroing it in until I grasped what was going on.

This is no problem when stalking but makes the thing usless for the annual club sporting rifle competition.
 
A correctly fitted moderator should make no difference to a rifle! Problems normally arise due to bad (off centre) screw cutting, badly fitting rear bushes (if fitted), extra weight causing barrel 'free floating' problems, loose baffles in certain models.
Increased temperature will eventually affect the accuracy of any rifle, but 3 shots shouldn't make any noticeable difference.
I would check to make sure it is ok with the moderator off first, then work through the above until you hopefully find which of the problems is causing the issue.
What sort of Mod is it?
MS:)
 
Ok now i'm starting to worry that the mod is not fitted properly. I took it off last wekend for a few shots and the zero raised by about a foot! I had assumed that the muzzle flip was reduced by the significant weight of the moderator, hence the reason it was striking higher. It does kick like a mule without it on! When I screwed it back on it returned to the original zero.

I tried slipping a tenner between the forend and barrel with and without the mod on and all is ok. When screwing it on it does get slightly tighter at one point right at the beginning but runs perfectly after that. I have noticed that by taking it on and off there some very fine circular hairline scratches appearing on the barrel where the back end of the mod sits. Is that a sign of problems? Should I take it back to the gunsmith?

The mod is a PES T12 and the rifle a Tikka M65. It was screw cut recently and the mod fitted by a gunsmith just over the Humber who came highly recommended.
 
Was it a general gunsmith or a dedicated rifle builder? Have you spoke to said gunsmith about the issue? That would be my first point of contact.
Secondly, how much experiance shooting the rifle and calibre have you had.

When I got my .270 it was a bit of a different animal the the .223 and heavy barrel .243 I'd shot before. I found I needed to get the gunfit sorted and practice a bit harder to get consistant results. That said, sorting the fit made a huge difference to felt recoil.

I have a M65 and can get a consitant 3 shot group from cold no problem. I take the mod off between groups though to let it cool (I did with the t8 anyway, the Thirdeye doesn't seem to holt the heat as much).
 
He builds custom rifles, and does screw cutting and so on, and no one has a bad word to say. Not spoken to him as didn't think there was anything to speak to him about, I had put the rising shots down to heat of the barrel/mod.

Not had a huge amount of experience with this calibre, hence the reason i've been practising, so i'm not able to rule out human error just yet. The thing that has me concerned is the mention that the moderator should make no difference to the rifle, well it makes a huge difference to the zero on mine, i'd have to drop it about 12 clicks before it would even be on the paper!
 
The moderator should certainly not make that much of a difference. The internal bore of the moderator should be slightly larger than the bore of the rifle, the bullet should pass or 'shoot' straight through the middle. There are two other things i would check:

1) That the barrel is clean without an excess of oil etc.
2) Check the crown for visible signs of damage, if the crown is damaged the expanding gases will be released unevenly behind the bullet, affecting its stability in flight.

I would certainly contact the guy who screw cut it for you.
 
It will affect the zero and normally does bring it down due to the weight of it on the end of the barrell, but it shouldn't affect the accuracy or 'grouping'. Does the rifle group accurately without it? You need to establish that first before you can point the finger at the Mod for definite!;)
MS:)
 
HI Steve

I had a moderator on my rifle, when i took it off i found that my point of zero was 7" high.
Had no problems with it on and no problems with it off.
However i do not take it off when zeroed with it on, Only for cleaning, Then check zero again.
 
HI Steve


However i do not take it off when zeroed with it on, Only for cleaning, Then check zero again.

You're asking for trouble there mate!:eek:

You should never store your rifle with your moderator left on, and taking it on and off between outings will not affect your zero either. Moderators are full of very corrosive gases and vapours which will eventually 'eat' the end of your barrel! This is why steel mods don't last too long! Even stainless barrels will suffer. My brother just had to fork out for a new Sauer barrel for the same sin.
MS:)
 
Steve29,

If you have any worries speak to Steve as I am pretty sure that's who your hinting did the work for you. He would rather talk to you and put your mind at ease and have you happy than this worrying. Add extra length and weight at the muzzle end of the barrel is going to effect the harmonics and so will change the POI. If it does not then you very lucky in that with the mod on and offf you hitting the same Node with that ammunition. Most of us are not that lucky :(.

When I shot my 25-06 with the mod off to see what the effect of removing it after zeroing it with the mod fitted was I was surprised at how much higher in elevation that the un-modded shot hit. The 6.5mm does not hit anywhere near as high with the mod removed. The Military stepped barrel may be helping there as the steps reflect the node wave and may actually dampen it's efects. Or so it has been explained.

Oh if your rifle has a floated barrel and it's now touching slightly witht eh mod fitted them it will probably be better if this was removed so the barrel was floated all the time. With the mod fitted the channel might be tryign to act as a bearign surface and as it was not intended to it might not be central. The barrel wants to be bedding at the point proeprly or floated properly there rally is not in-between point on this.
 
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