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onehole

Crosshair "Hop"

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Some or most of you must have done some dry firing ,,,yep?,,,,ok,,,,,,some or most of you would have noticed varying amounts of crosshair movement and from a little research on the net there seems to be quite a few reasons /causes and remedies for this .Although I do not use my 223 Howa Varmint for comp etc but I obviously like to get the best out of it and it seems that I need to take quite a firm hold of this rifle to negate the "hop",,,,and the same hold also produces more consistent grouping.On my RPA,s etc and with only a light hold I observe hardly any movement and do not have to work too hard at extracting super tight grouping,,,is it the weight of the RPA,s,,the short lock time,,,better build etc that is helping here ??I use the same rest format with the howa but without a good grip it doesn,t reward me....I,m suspecting a longer lock time is contributing in addition to the light grip??,,,The direction of movement seems to be to the left and down,,,,its very small but probably amounts to half a minute,, what do e think,,,,,,,,O

[scope is Nightforce and previously used on other rifles.no scope problem]

 

Just adding this to my post,,,,,,,The trigger has been lightened and I have fitted an overtravel stop ,,,so absolute minimal human movement on the trigger.....

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Swaro 6-30, same thing. Have never properly stopped it. Heavyish barrel in AICS stock. Thought it was just a Remy thing. Maybe not.

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I always find my heavier rifles behave better under recoil but theremay be more to it than weight vs recoil but im not sure

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Can anyone reading this post and not dry fired and not watched their reticule against a target under dry firing please have a go and report,,,thanks,,,,,just interested in what people find,,,,,,,,O

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Shooting my FTR rifle, I always dry fired a few times once getting into position and if the reticle moved in relation to the target, it was an indication that the rifle wasn't properly settled in the rear bag.

 

I'm talking about a custom rifle here, just below the weight limit with a very stable bipod on the front and a very heavy bag at the rear, with no contact between the stock and the shooter.

 

So my take on it is that the whole rifle is moving and in order to stop it from happening you need to get everything planted and stable.

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Nobody tried this yet, or is down to something in the water in the westcountry?

Haha,,,,,yea ,,,thought I would get a few more takes on this,,,,,,I even tried a different scope this week ,,,,same happens ,,,,spent some time trying to better evaluate whats actually going on and tried varying methods of hold and firmness of grip ,,,holding fore end,,self supported fore end,,,,trigger pinching etc etc and also mounting the whole thing in my neavy benchrest,s,,,,,Although a firm hold improves or rather lessens the "hop" this makes for an uncomfortable and stressy shoot,,,not good practice.,,,,I really don't think its just one thing in isolation but I have gone back to my normal lightish hold and given more attention to trigger pull and follow through,,,the "hop" is still there but,this does seem to provide more consistent good grouping.,,,,

Anyone else notice "the hop",,,???....O

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I've had it....disconcerting until I noticed it exactly correlated with my heart beat-just enough with the 'right' hold and of course very high mag (36+) -it's not much and 20x won't show it for me. This cause wasn't related to dry/live firing as it happened prior to trigger (2oz;12 lb rifle aprox) though I can't rule out excitement completely. I have noticed with completely free recoil-no contact at all with rifle other than pinching trigger and trigger guard withindex finger and thumb it don't occur,implying it's body contact.Nor with a 20lb heavy gun,maybe too much for an older heart to push around,or less excited etc etc.

 

There may well be other reasons,though 'offhand' hard to see any cause without body contact.THis was of course a rythmic,regular repeated movement-not a one off hop,as maybe with trigger pull/lock/etc

 

a hairline cracked rear scope mount (-aircraft grade aluminum!) did disturb reticule on firing-and POI,of course-but that's clearly different-once spotted-it looked like flyers-only about one in five went measureably out,so not easy to diagnose on the shooting bench.

 

g

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Thinking about it again and purely IMO of course, it's root cause is the firing pin striking. I'm sure of that. Why that causes the reticle to move is what we're trying to establish.

 

Better settling in the bag, rest, shoulder or a different hold may be damping the vibration rather than just stopping the gun from moving. It could be a higher frequency of disturbance happening here than just simply a shift in position of the rifle as a whole.

 

I have seen it with no body contact other than the trigger finger, so I'm convinced it's not only body contact, although that may contribute.

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Thanks,,,,well we do know it exists,,,I,m now wondering when it actually occurs,,,is it immediately after pull or during the pin stroke or even when the pin strikes,,,,,,too fast for me to identify?,,,,Can I call up John M H on this,,,,,,,J,,, do you remember me selling you a big S @ B somewhile back down at Zelah and you picked up on its reticule movement?,,,,was that a fault with the scope or this same "hop" we,re on about? ,,,,I never got to know,,,,regds ,,,O

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No problem with the scope. I used to do a lot of dry firing when shooting High Power with my T2k. I also used a Konsberg Laser Dry Fire Training System that plots on a screen your rifle movement just before and after trigger release. With a high mag scope you will probably see a 'jump' as the firing pin is released as JSC hinted above, I don't think it is anything to worry about as immediately after that there is a whole load of things happening that are going to take the sights off target. I used to get a definite jump with the T2k (this has a very fast lock time). The faster the lock time the less disturbance there will be between the sight alignment at trigger release and ignition but there will always be some movement as things are 'moving', higher magnification may make this more obvious but I reality we are talking milliseconds (T2k is under 2ms).

 

For dry fire practice I would recommend getting a IOTA

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Thanks John,,,great reply!!,,,I was thinking lock time can help,,,bears out why my RPA,s seem easier to shoot,,,,,think I can put this all to bed now,,,,,,cheers John,,,,,D

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Are you clicking on an empty chamber, or using snap caps? I've noticed that some rifles do the hop more than others -and those that do often combine it with a tiny bit of bolt handle movement. I have a pet theory it's to do with a degree of overtravel that a round (or decent snap cap) takes up.

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I reckon if you could find a way to see if it happens with a live round, you wouldn't see it happening. But that's only my theory. Using a snap cap might prove that.

 

As John says, there are a lot more things happening with a live round after you pull the trigger, so I don't think it should really be a concern, but if it becomes a doubt in your mind you need to eliminate it or overcome the doubt, otherwise the psychological effect of it alone could affect your score...

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I,ve just finished making a snap cap out of a spare case,,,its sprung just about right I reckon so will compare with dry firing on an empty chamber which is what I have been doing!? The bolt handle makes a small twitch whether snap cap in or out,,,,will get on a target hopefully tomorrow and compare any differences in "hop" if any........This is the sort of thing you could ask students at a uni to investigate with all their clever measuring wizardry and stuff,,,,,,,,

post-41-0-45192400-1487277802_thumb.jpg

 

 

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Are you clicking on an empty chamber, or using snap caps? I've noticed that some rifles do the hop more than others -and those that do often combine it with a tiny bit of bolt handle movement. I have a pet theory it's to do with a degree of overtravel that a round (or decent snap cap) takes up.

Good point. Empty. Will try with a fired round, or is that not enough of a 'load'

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Just seen a very nice clear video by Si snipe showing the scope level bubble twitch a tad when the trigger breaks in dry fire.

 

gbal

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I've had this phenomenon with every rifle I've owned. It jumps down to the right when I'm shooting left handed. And down to the left when I'm shooting right handed. I think it's a combination of firing pin strike and minute muscle tension in the shoulder. I've only noticed the difference in jumps because I can shoot either handed.

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Out with the Howa today and spent some more time checking out the "hop",,,,and to see what the difference was between empty chamber dry firing compared to dry firing using my snap cap as a dummy case/primer.....It was plain to see that there was significantly less "hop" with the snap cap in place but unsure what this actually means other than thinking that in live firing the firing pin release,travel and its effects may be significantly reduced,,,,still convinced lock time is more of an issue with getting the best out of my Howa but then that might be me and I cant perform the perfect follow through every time....My Sako 75 is quick and RPA,s super quick guess I,ve had it easy over the years,,,,,,,,Thanks for all your inputs,,,,,,,,O

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I've found it with all of my rifles. There's the issue of the inertia of bits of metal moving around, how square I am to the rifle to obtain the best straight through pull without applying an off-axis squeeze, heartbeat, lightness of grip, the forward motion of the firing pin and contact with the FP shoulder itself plus the slight bolt handle lift on dry firing. That's a lot of things going on!

 

I have found that altering body position can help reduce it a little (fractionally) hinting that perhaps my pull isn't as axial as it ought to be (got to work on that). The lift on the bolt handle may also be causing a small reaction.

 

I think there may be more damage done to groups over-analysing this though than simply settling into the position that seems to give the steadiest dry firing position, and returning to basics seems to work every time for me. If the cross-hairs are not bang-smack centre when looking away and then looking back through the scope, the grouping will be off. If I haven't got the right LOP (adjustable), my groupings will be off. If cheek position isn't correct, groupings will be off. There's so much else to worry about.

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