Rimfire grouping query

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Rimfire grouping query

Post by Member-Deleted » 23 Apr 2018, 10:34 am

Hi, I'm hoping to tap into the experience on this forum because I'm at a loss to explain this. On Sunday, I took my new acquisition (an old CBC bolt action) and zeroed it at 25m with 5 shot groups and was happy with the results. Then I moved to 50m with the same box of SK standard ammo and couldn't hit the side of a barn. I couldn't figure it so I threw some Eley subsonics through it which weren't great but at least resembled a group.

For reference, the top left group in the first photo was my second lot of 5 shots at 25m. In the second photo there were also 5 shots at the top left aiming diamond (but only 4 hits - the 5th is stray at 12 o'clock in the first photo). The photos have loaded sideways - the SK group at 50m is strung left to right, not vertically. The sides of each black diamond are 40mm (it's how they printed).

I don't think it is normal for groups to open up like that so dramatically at such short distances so what might have caused it? Conditions hadn't changed, there was no real breeze to speak of.

I also got quite a few misfires (1/15) with the SK - the rim looks like it's being struck firmly but one I hit 3 times before it fired. Was also getting misfires from other brands I tried but not as often (maybe 2/50). Ammo or my firing pin?

This is a plinker I hope to use for fun in metallic silhouette (not for hunting or serious paper punching) so I don't expect tack driving, but I'm also baffled by the huge change between 25 and 50m with the same ammo.
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Re: Rimfire grouping query

Post by bladeracer » 23 Apr 2018, 10:47 am

Have you tried at close range again to confirm it still groups well?

Could it simply be that the sight picture, or aiming point doesn't suit you at that range?

Assuming iron sights, the Eley Subs looks like a very respectable group.

Measure the firing pin protrusion from the bolt face to confirm it is reaching almost to the breech face. The strikes look good so I don'think it's a spring issue. Does your ammo shoot fine in other firearms?
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Re: Rimfire grouping query

Post by brett1868 » 23 Apr 2018, 11:25 am

a couple of questions....when shooting the different brands / types did you shoot groups one after the other? Usually when switching types / brands you may need a dozen or so shots to get the barrel settled for want of a better term. The case has 3 solid strikes on it so I'm at a loss as to why it didn't fire, old ammo maybe? SK is generally on the premium side of 22LR and I've never had that brand fail. I shoot a heap of 22lr in both rifle and pistol, CCI, RWS, Eley, Lapua, Winchester and a few others and haven't seen an issue like the one you're having so I'll be following this one for sure.
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Re: Rimfire grouping query

Post by Member-Deleted » 23 Apr 2018, 11:37 am

bladeracer,
Damn, I didn't think about trying it again at the 25m to confirm the groups. I was jack of it by then and stuck to shooting my .223 but I was using the same target format and aiming point for that at 100m with no worries.

I only have this 22LR so don't know if the ammo works in others. Regrettably those are not iron sight groups, I was using a scope.
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Re: Rimfire grouping query

Post by Member-Deleted » 23 Apr 2018, 11:53 am

Brett,
the ammo was bought new a few weeks ago although I guess it could have sat in store for a while. The previous weekend I also tried other brands (CCI Standard and Blazer, Win T22, RWS subs, American Eagle, Highland RX subs), firing at least 20 or 25 rounds in 5 or 10 shot groups and the SK was consistently the best (RWS and the Highland subs good too). I had occasional misfires with other brands too but they all went off on a second strike.
One thing I noticed that day was one brand would print at 2 o'clock high from point of aim, the next brand with same POA would print low and left. So on Sunday I was getting excited that the SK was hitting more or less where pointed at 25m and I hoped that would carry over to the 50.
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Re: Rimfire grouping query

Post by Gwion » 23 Apr 2018, 12:36 pm

So many possible variables. Like parallax issues that just coicidently happened while you shot those groups. Positioning of the stock on the rests so that some fixture such as a sling stud is fouling on the rest..... best thing to do is illiminate variables. Use one ammo type. Shoot a ton of ammo at both 25 & 50m. Concentrate on rifle-rest set up and shooting technique.

Also, start by giving the bore a good clean and check the crown for defects.
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Re: Rimfire grouping query

Post by pomemax » 23 Apr 2018, 12:48 pm

Its an second hand bolt action give the chamber a good clean AND the bolt ,look for old strike marks in the chamber where the pin has been hitting bet you find one
.as brett said different ammo different results don,t forget rimfire ammo its not like centerfire it can vary a fair bit even in the same brand what I would do find what shoots best for you then thoroughly clean the bore then stick with one brand it may take 20 odd shots to settle down after cleaning depending on the amount of wax the manufacture uses as a coating .
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Re: Rimfire grouping query

Post by Member-Deleted » 23 Apr 2018, 12:59 pm

Gwion,
Thanks for the input. Half my problem is not knowing what variables could apply. I try and keep a consistent set up and smooth technique ( the misfires are actually a good training tool in that sense). There is no sling swivel to foul the sandbag. I installed the rings and scope myself. Could I have buggered that up somehow? The reticle is level, the screws are tight (but not too tight). I did clean it when I first got it - a drowning of the bore in G96, nylon brush, tons of patches through on a jag. It looked like a coal miner had blown his nose in the patches, but they started coming out clean. I'll take a photo of the crown because it looks undamaged to me but I'm not sure I'd recognise damage that wasn't bleedingly obvious.
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Re: Rimfire grouping query

Post by Member-Deleted » 23 Apr 2018, 1:21 pm

Cheers Pomemax. I'll check the chamber and bolt as you suggest.

Excuse the noob question but both you and Gwion have suggested giving it a good thorough clean. I'll search the forum for a cleaning thread but I take it I'll need something more than the slap & tickle I gave it with G96 but less than the effort in Just Starting's thread this morning about his Martini Henry
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Re: Rimfire grouping query

Post by Gwion » 23 Apr 2018, 1:31 pm

If you are new to shooting then it can be very difficult to pick up small changes in technique or position that could have a big influence down range. Hell. Even 'experienced' shooters have a tendency to look for faults in gear and ammo before looking at their technique or basic position/approach to the firearm. For instance, tou might not have sling swivels but tyhe 'pistol grip' on the stock might be resting on your rear bag.....

Not saying that this is the case here but it is definitely possible.

Unless there is something effecting stabilisation (like a damaged crown) of the bullet, a rifle that shoots tight at close range 'should' shoot tight at longer ranges. At least, the groups should resemble each other in comparative size and shape. Ie: groups should be roughly 2x size at 50 than at 25m. 25m is close enough for a slightly damaged crown to have little effect on group size but at 50m the 22lr is slowing quite a bit and any instability will have taken a toll. Same can be said by minor issues with technique.

I've had my licence for about 5 years now (long enough to learn and recent enough to remember 'relearning') and hadn't shot regularly for probably 20 years before that. I found some sessions were good and others bad to begin with. Then i started focusing on one element of my technique for each session and things started to improve dramatically in a short space of time.

Best way to check it out is ask a good shooter to try it out for a few groups. If it does the same thing it is likely rifle/ ammo. If it shoots as well as the shooter then it may well just be part of your learning curve.

One last thing is double check your scope and mount screws.
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Re: Rimfire grouping query

Post by Wm.Traynor » 23 Apr 2018, 1:48 pm

Member-Deleted wrote:
One thing I noticed that day was one brand would print at 2 o'clock high from point of aim, the next brand with same POA would print low and left. So on Sunday I was getting excited that the SK was hitting more or less where pointed at 25m and I hoped that would carry over to the 50.


I would be surprised if different brands did Not have different points of impact :) Alter the scope adjustments to get the POI where you want it :thumbsup:
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Re: Rimfire grouping query

Post by Member-Deleted » 23 Apr 2018, 2:00 pm

Gwion,
It's definetely possible.While I have had some years of experience with ISSF pistol matches I am 100% new to the techniques of rifle shooting. I last shot a rifle 30 years ago and had never looked through a scope until a few months ago.
What you are saying intuitively makes sense to me - if it can group consistently with Brand X at this distance, then it should continue to group similarly well at other distances even allowing for increased distance. I'm thinking I'll give it a really good scrub then buy a brick and practice.
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Re: Rimfire grouping query

Post by in2anity » 23 Apr 2018, 3:38 pm

I remember there was a bad batch of geco years ago - grouped fine inside 50m but past that they were weirdly sub-optimal (in an BRNO mod2 FWIW). Flat-out couldn't be used on the 100m rams due to the terrible accuracy. Old dude at the range bought 5000 of them (allegedly "bargain" price I might add go figure) so the poor bugger was stuck with them. He used to swap ammos during the match for the turkeys and rams. A similar anomaly can be witnessed shooting undersized (aka "to spec") lead through a microgroove marlin - the shallow grooves don't stabilise the projectile like hey should, basically meaning the round is spun slower than design and loses stability a lot sooner than it should; acceptable for up to 50m but past that they are terrible. I wonder if a similar thing is happening, i.e. if it has anything to do with that particular batch of projectiles and your particular barrel?
At what point does lack of maintenance become patina?
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Re: Rimfire grouping query

Post by Conallin24 » 29 Apr 2018, 10:41 am

One thing I like is that you said “misfires are good for working out how you are shooting” because it’s dead right. One thing you can do at home is shoot with empty cases or dummy rounds. Dryfire even if it’s for 5 minutes a day is very valuable for skill development.
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Re: Rimfire grouping query

Post by Member-Deleted » 14 May 2018, 9:27 am

I free floated the barrel on the weekend by simply placing some thin shims under the action, front and back. Didn't remove any timber from the stock. Groups looked OK and were consistent with Eley standard. Still had a few misfires though requiring a second strike.
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Re: Rimfire grouping query

Post by tom604 » 14 May 2018, 11:52 am

if you are having misfires with all your ammo i would be calling a gunsmith to get your pin fixed, that last group at 25 or 50? if its at 50 its good enough for plinking and rabbits :thumbsup:
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Re: Rimfire grouping query

Post by Member-Deleted » 14 May 2018, 12:39 pm

That was the best of several attempts at 50 yards, but the other groups were all at or just under an inch so I am really satisfied with it.
I'm embarrassed to confess that I hadn't realised before that session that at least part of the problem was I must not have had the scope 100% focused. It has always looked really clear and in focus to me out of the box but when I was at the range resighting and checking the scope after floating the barrel, I fiddled with the focus and it became even sharper (and the crosshairs thinner). It was a bit like the time years ago I tried on a mate's glasses and realised I needed glasses. Noobs, amIright?
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Re: Rimfire grouping query

Post by Wm.Traynor » 14 May 2018, 1:06 pm

BBSS,
You say that you, "fiddled with the focus". If you want to get really fussy:-
1) Unlock the ocular lens and wind it out i.e. towards you.
2) Imobilise the scope while it is pointed at a section of clear sky.
3) Observe the clarity or otherwise of the reticle and wind the ocular eyepiece forward say, two turns. Observe the effect on clarity.
4) do not induce a shake into the scope while observing results.

ps it takes a looong time ;) :thumbsup:
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Re: Rimfire grouping query

Post by sungazer » 15 May 2018, 10:02 am

Mate the very best of shooters make mistakes all the time. I have seen some of the worlds best shoot on the wrong target, a competition ending score-wise mistake for them. There is so much to concentrate on its nearly impossible not to make a mistake until you have a routine well ingrained and even then things happen that put you off.
I often forget to set my Ocular focus as I have to wind it in to get the bolt in and out which must be done before getting up from the mound. I have to wind it all the way out then a 1/4 turn in. At least its not one that has the lock rings.
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Re: Rimfire grouping query

Post by p3seven » 15 May 2018, 11:02 am

If the rifle is of unhnknowwn provenebce it may have a bent barrel.
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Re: Rimfire grouping query

Post by bladeracer » 15 May 2018, 11:39 am

p3seven wrote:If the rifle is of unknown provenence it may have a bent barrel.


Does a bent barrel effect accuracy though?
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Re: Rimfire grouping query

Post by bladeracer » 15 May 2018, 11:50 am

This one shot pretty good.
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Re: Rimfire grouping query

Post by Gwion » 15 May 2018, 1:22 pm

Maybe you need to clean the bolt. Too much grease, oil or crud will interfere with a good strike from the firing pin. Good place to start by giving it a good clean up and then VERY lightly oiling the internals.
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Re: Rimfire grouping query

Post by Wm.Traynor » 15 May 2018, 2:36 pm

bladeracer wrote:
p3seven wrote:If the rifle is of unknown provenence it may have a bent barrel.


Does a bent barrel effect accuracy though?


A barrel that has been straightened will not group as well as a straight barrel. Got that out of, "Competitive Rifle Shooting", back in the olden days :D
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Re: Rimfire grouping query

Post by bladeracer » 15 May 2018, 2:42 pm

Wm.Traynor wrote:
bladeracer wrote:
p3seven wrote:If the rifle is of unknown provenence it may have a bent barrel.


Does a bent barrel effect accuracy though?


A barrel that has been straightened will not group as well as a straight barrel. Got that out of, "Competitive Rifle Shooting", back in the olden days :D


But does a bent barrel shoot okay if you don't straighten it?
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Re: Rimfire grouping query

Post by tom604 » 15 May 2018, 6:42 pm

depends how bent,a 90 degree bend may move the poi a couple of inches :allegedly: :thumbsup:
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Re: Rimfire grouping query

Post by Wm.Traynor » 15 May 2018, 7:24 pm

bladeracer wrote:
Wm.Traynor wrote:
bladeracer wrote:
p3seven wrote:If the rifle is of unknown provenence it may have a bent barrel.


Does a bent barrel effect accuracy though?


A barrel that has been straightened will not group as well as a straight barrel. Got that out of, "Competitive Rifle Shooting", back in the olden days :D


But does a bent barrel shoot okay if you don't straighten it?


I confess: I have no idea. The author. Jim Sweet, did not go in to that. First things first however. Get it on paper and try it. Not volunteering my rifle ;)
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Re: Rimfire grouping query

Post by bladeracer » 15 May 2018, 9:34 pm

tom604 wrote:depends how bent,a 90 degree bend may move the poi a couple of inches :allegedly: :thumbsup:


Sure, but if you zero it I'm guessing it would still group reasonably well, probably not as well though as the bullets are probably deformed in the curve.

I lean toward the view that a perfectly straight barrel is virtually impossible, particularly in hunter-weight, thus all barrels are bent to some degree anyway.
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Re: Rimfire grouping query

Post by marksman » 16 May 2018, 10:53 am

If you ask someone who machines the barrels they bend with the weight of the barrel, in the lathe
hence the forearm bedding to shorten the length of "especially" thin whippy barrels to get them to shoot, look at factory rifles with forend pressure pads
I'm sure that a slight bend wouldn't hurt as a barrel does whip when shot,
but we all know that if the barrel is touching at one side of the forearm it will not shoot well
I think it will be more than one problem in the barrel that would make it not a good barrel
I would not do any testing of a 22 rimfire at 25 yards as you will only see what it is going to be like with the ammo at the distance you will sight it in,
IMO 50-75 yards for a 22 rimfire
some rifles wont shoot very well and you cant make them :allegedly:
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Re: Rimfire grouping query

Post by bladeracer » 16 May 2018, 11:17 am

marksman wrote:some rifles wont shoot very well and you cant make them :allegedly:


I have one of those :-)
My father-in-law's Remington 510. The bore is tightish at both ends for an inch or two, but the whole length of the bore barely touches a .224" jacketed bullet. I put it down to many decades of "fishing" with the muzzle in the water to stun the fish - it's just one long bulge.
The only acceptable accuracy I've managed from the original barrel is by shooting jacketed .224" bullets down it.
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