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Accuracy woes


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Until fairly recently my 17 Mach IV hasnt missed a beat and has nailed pretty much everything the dot has landed on (baring acts of God, worm holes and mini cyclones :P )

 

Not so anymore :) Over the last few weeks I've been missing more and more fairly easy shots.

 

This one's got me stumped. I havent changed powder weight, the brass, bullet heads or primers. Bullet seating depth is the same.

I've been round all the screws and found a few loose ones on the scope rings :blush: but rectified that problem and tried for zero but no joy. Get a respectable group at 200yds (my zero) then just to confirm the zero the next few shots scatter :( . I did swap the scope for another scope from my .223 but dont think this is the problem as the .223 with that scope was accurate all the way out to 600yds.The M4 initially shot accurately with this scope on anyway.

 

As a last resort the other day I even cleaned the barrel :lol: but this hasnt brought the accuracy back.

 

Anyone got any ideas before I use it as a tomato stake?

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Not the crown. Crowns just don't deteriorate.

I would instantly suspect the scope. I have had some scopes that were fine as long as I didn't adjust them. Once I did, I had hell to pay getting them to settle back down. It is, after all, the largest variable in your particular equation. The trouble started after swapping scopes?

 

If the confidence in the scope is high, then look to the brass. It may be getting tired and unable to deliver uniform pull weight. No fear. You'll get it figured out.~Andrew

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Not the crown. Crowns just don't deteriorate.

I would instantly suspect the scope. I have had some scopes that were fine as long as I didn't adjust them. Once I did, I had hell to pay getting them to settle back down. It is, after all, the largest variable in your particular equation. The trouble started after swapping scopes?

 

If the confidence in the scope is high, then look to the brass. It may be getting tired and unable to deliver uniform pull weight. No fear. You'll get it figured out.~Andrew

 

andrew i'll think you'll find a crown can just deterioarate i.e. if it has sustained damage

 

thats why i was asking what it was like and not saying it was that

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Spud,

 

The crown is spot on. Its well recessed and I take care not to to damage it. The PacNor tube has only had about 700 rnds down it.

 

Andrew, the brass is on its seventh firing now. I've been using 16.5gn of H4198 and its doing about 3850fps. Primer pockets are still tight (.223 winchester brass rolled to make 17M IV brass). When seating the bullet I dont feel discernible difference between cases. Brass has been annealed and I only use a neck die.

 

I will check the scope on the other rifle too make sure.

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Assuming the barrel is clean I would also suspect the scope.

 

700 odd rounds, maybe time to check the seating depth as you will have some throat errosion. May need to seat them a bit further out to maintain the distance to the rifleing but that should NOT cause the problem described.

 

Have a poke round the the crown with a cotton bud, the end of the bore should NOT pick up any cotton fronm the bud, if it does then recrown it. Again though a worn/damaged crown wont shoot well one minute and crap the next.

 

A

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The scope is off the M4 and back on the .223 and bore sighted. All being well Im off to the range tomorrow to see if it is the scope. Perhaps a NXS cant hack the recoil from an M4 :)

 

I've just checked the crown with a bud and its very smooth. Fibers are not being pulled from the bud end and there's no snagging etc.

 

I would be very surprised if it is the scope. The loss of accuracy has been a gradual process rather than a sudden one.

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Guest varmartin

So to get an angle on this oddity ....every thing is the same , with no problems until you swapped the scope ??

 

I would say ....swap the scope again and re try ...

 

Or is it / are you using a moderator ?...is it that ?

----------------------------------

 

Sorry ...looks like you posted as i was mulling it over ....

 

Let us know how you get on ..

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I,d put money on the barrel being badly copper fouled. It doesn,t take much doing on a .17 cal.

I,ve had several guns in lately of various cals, all with the same problem. The owners were cleaning them regularly, but using stuff like kg1, or forrest bore foam . The swore blind the barrels were clean.....until i soaked them in sweets.

The worst was a blaser 300 win mag. its accuracy went off. There was layer upon layer of copper, then carbon. the gun took a full day to get properly clean . The barrel is a bag of that which promotes growth and vigour, and the only cure was to then shoot it with moly bullets. Its kept the fouling right down, and it "oneholes" again.

Check the bore again with Sweets buddy.

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I,d put money on the barrel being badly copper fouled. It doesn,t take much doing on a .17 cal.

I,ve had several guns in lately of various cals, all with the same problem. The owners were cleaning them regularly, but using stuff like kg1, or forrest bore foam . The swore blind the barrels were clean.....until i soaked them in sweets.

The worst was a blaser 300 win mag. its accuracy went off. There was layer upon layer of copper, then carbon. the gun took a full day to get properly clean . The barrel is a bag of that which promotes growth and vigour, and the only cure was to then shoot it with moly bullets. Its kept the fouling right down, and it "oneholes" again.

Check the bore again with Sweets buddy.

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I,d put money on the barrel being badly copper fouled. It doesn,t take much doing on a .17 cal.

I,ve had several guns in lately of various cals, all with the same problem. The owners were cleaning them regularly, but using stuff like kg1, or forrest bore foam . The swore blind the barrels were clean.....until i soaked them in sweets.

The worst was a blaser 300 win mag. its accuracy went off. There was layer upon layer of copper, then carbon. the gun took a full day to get properly clean . The barrel is a bag of that which promotes growth and vigour, and the only cure was to then shoot it with moly bullets. Its kept the fouling right down, and it "oneholes" again.

Check the bore again with Sweets buddy.

 

 

Thanks for that Baldie, Ill give it whirl and see what happens. If I clean it enough perhaps it will turn into a 20 cal :) ?

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make a plug for the barrel and fill it with butchers bore shine.

 

I'm with Dave with this one. i have had a 17 go off with bore fouling. i have left bore shine in for a week and it did not do anything to the bore,i have done it with custom rifles as well.

i would not recommend sweets left for a long wile far to much Ammonia.

 

ATB

Colin

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make a plug for the barrel and fill it with butchers bore shine.

 

I'm with Dave with this one. i have had a 17 go off with bore fouling. i have left bore shine in for a week and it did not do anything to the bore,i have done it with custom rifles as well.

i would not recommend sweets left for a long wile far to much Ammonia.

 

ATB

Colin

 

Thanks Colin,

 

You and Baldie could well be right. Ill check the scope in a bit and if that still works ( cant believe it wont) Ill attack the barrel with chemicals.

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If that is the situation then Wipeout is called for. I use Butches as a carbon remover, then in with TM solution to shift Copper. I had a 22.250 once that I thought wrongly was clean, only Wipout got it clean.

 

In order of effectiveness Wipeout is best, then TM and finally Butches IMHO.

 

A

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If that is the situation then Wipeout is called for. I use Butches as a carbon remover, then in with TM solution to shift Copper. I had a 22.250 once that I thought wrongly was clean, only Wipout got it clean.

 

In order of effectiveness Wipeout is best, then TM and finally Butches IMHO.

 

A

 

 

Hi Geoff

this is how i see what is happening in a bore. now i could be wrong but hey its my theory and I'm sticking to it.

when you shoot a shot down the tube of your rifle,what happens is small deposits of burnt powder and copper from off the bullets is deposited in the microscopic imperfections and the fire cracking in your bore.

but first you will get a layer of copper and then a layer of carbon.because the bullet is bigger than the bore so it seals the bore as it makes its way up and out your tube.

then you repeat the process over and over again.this leaves a layer of copper then powder then copper then powder and on and on and on.

so what you need to clean this off is a carbon and copper cleaner. but not one to aggressive as you do not want to make the internals of your bore any worse than it is all ready.

This is where butchers bore shine comes in to play. it was invented by a bench rest shooter in the USA and was made for soaking your barrel. now if its good enough for a bench rest shooter in the USA its good enough for me.

don't get me wrong there are faster working cleaners out there,hell i use them,but i can not think of a better one for this kind of job.IE soaking a barrel for a few days,then may be repeating the process.

forest bore foam is that which promotes growth and vigour. just sit back and think what you are doing when you spray this down your bore,yes at first it fills your bore because it foams up,then its bubbles burst and it runs down to the bottom of the bore.so you end up with only 1/2 your barrel getting treated.

my way is i have an end cap that has a solid end on and i put a piece of cork in the end to seal it. i then fill the bore from the action end with butchers bore shine and leave the rifle muzzle down in my safe.

what this does is 2 fold

1 and the most important is it gets the bore very very clean.

and 2 if the seal bakes then the butchers bore shine will not go in to your trigger and every where. it just goes in to the bole you stud it in :lol:

when i take the boreshine out of the bore i all so put it in a old bottle and use it again (up to 3 times) then i throw it away. :D:D

It a very very easy way of cleaning your bore,and should be done with even custom rifles. you will be surprised what you can miss, it even gives your chamber a quick looking at.

Ho and please don't go to high with the cleaner, just part way up your chamber.

 

Hope this helps

 

Colin

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I cant argue with your copper carbon copper carbon theory, if you think about it then it must be correct. I have never soaked a barrell in the way you describe, using Barts or TM I use several very wet patches then let it stand for an hour or two. I just found barts to be good for carbon but TM is better on the copper. Your way certainly guarantees fluid contact all the way up and that may be where I fall down. Neither of my barrels show much copper at all, I clean at about 10-15 rounds, I did Wipeout soak the PPC the other week but nothing unexpected came out.

 

A

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Hi Geoff

 

it does seem to work even if the hole argument ov the solution needs air to work. maybe this is y it does not damage your barrels. as it is not as strong when used this way.

 

one thing is for sure Geoff. if what you are doing is working for you then don't go changing anything.I'm not trying to covert anyone to do there cleaning my way, its just a possible solution to a problem.

 

ATB

Colin :lol:

 

PS i all so use barns cr10

shooters choice extra strong

and a few other things

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Col,

do you find this equally safe and successful the butchs bore shine soaking over a few days, for stainless and chrome moly barrels ?

 

Or do you do something different depending on material?

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Went the day badly!

 

Bore sighted the scope on the .223 and was only about 4" out at 100yds so a fairly promising start.

 

Gave it a handful and bought the POI close to my aiming mark and squeezed off a few. It was soon clear that all was not well :P I was getting a couple touching (it normally cloverleafs at 100yds if I do my bit) then the next two would move up a MOA vertically.

 

The goup tended to shift round the aiming marks etc.

 

Too be fair, it wasnt a true comparison. Whent the scope was on the .223 the scope rings were metal on metal contact (rings on scope body). When the rings and scope were transfered to the Mach IV something was amiss!

 

I like to have scopes optically centred (at least for windage if possible) but somewhere in the transfer process and mating with the new action/mounts I'd lost about 7-8 MOA which when you've only got about 30 MOA to play with is a lot. Ok, I appreciate it probably still has more than enough windage for my purpose but I like things just so.

 

I set about by inserting paper between the scope body and rings at the front and rear to move the POI the necessary 7-8 to optically align the bore and scope and POI. This seemed to work as I have had sonsistent good shots at distance but when tried on the .223 things seemed to move. This coupled with a massive copper build up has screwed the accuracy up.

 

Has anyone tried paper inserts to correct POI and had any success doing it or is just to unstable/unpredictable and caliber specific?

 

I've put some Burris Sigs on it now with +/- 10moa inserts which seems to have brought the scope over when bore sighted. Just need to go back and re test with the .223.

 

 

 

Rather

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ive never used paper but i have tried and used old 35mm film negatives as shims

 

would paper get wet and go mouldy

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In my early rifle days 30 years ago film was regularly used but I bent scope tubes using it.

 

Experiance now says to me that the rings are not correctly aligned with the bore.

 

I thought the issue here was with a .17M4 not a 223. If you are saying that this scope that was fitted to the M4 is now faffing about on the 223 you may be getting somewhere.

 

A

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Col,

do you find this equally safe and successful the butchs bore shine soaking over a few days, for stainless and chrome moly barrels ?

 

Or do you do something different depending on material?

 

 

Hi i have used this on both, but what i do after the hole process is over is i make sure i all ways condition the barrel with some good oil. as this will get rid of everything.

 

ATB

Colin :P

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In my early rifle days 30 years ago film was regularly used but I bent scope tubes using it.

 

Experiance now says to me that the rings are not correctly aligned with the bore.

 

I thought the issue here was with a .17M4 not a 223. If you are saying that this scope that was fitted to the M4 is now faffing about on the 223 you may be getting somewhere.

 

A

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A,

 

The issue is potentially with both? Intially I thought it might be just the M4 but there may indeed be another issue, that being the scope. The choice of paper probably wasnt the best in hind sight. The scope rings were only torqued down using finger and thumb pressure and a small hexagonal head screw driver so i dont think sufficient force has been applied to bend the body etc. My money is still on the bore being foulded out.

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I have not had a lot of experiance shooting .17 caliber rifles but I've cleaned a few gunsmithing....

 

The last one had hard carbon deposits in the throat for about an inch after the owner fired 200 rounds with out cleaning that barrel. I did a chamber cast and measured it. The grouves were filled completly and this was sizing the bullet in the throat. No wonder that it didn't shoot!

 

Try

 

http://www.bosesguns.com/v/vspfiles/photos/ios10215-2.jpg

 

Iosso Bore Cleaner Paste 1.5 oz

http://www.iosso.com/MivaStore/merchant.mv...ode=GunCleaning

 

http://www.6mmbr.com/borecleaning.html

 

http://www.benchrest.com/forums/showthread...e+Cleaner+Paste

 

Glenn

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