Canadian Airgun Forum

So I've got a full power optimus and it can hold decent groups if I do my part doing about dime sized groups at 20 metres but, even slight changes in hand placement move the poi considerably. Groups are still good but poi is all over the place. So, how can I reduce this? So far I've cleaned, deburred, relubed all the internals and added a bearing washer above the top hat. There's a little buzz left and I was considering tarring the spring to tone it down a little more. I'm not overly concerned with top power but would still like it to be somewhere in the neighbourhood of 12ft/lbs since it's going to be used primarily for small game.

I was considering mostly lowering the power to try and achieve my goals by either putting in the detuned Canadian spring and slight shimming or reducing pre-load with the full power spring. Ideas?

Search for "Artillery Hold".

Basically rest it on your hand without touching the sides of the forend. Let the springer bounce back and forth.

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-Rick

Brocock Concept .22
3 Crosman MK 1 pistol .22

In my experience the best way to get top accuracy out of a Crosman break barrel is to get rid of it and buy something else. Haha.

What I'm saying is with small changes in where my hand rests along the stock, there are large changes in poi. On inch either ahead or further back on the stock moves usually poi left or down enough to be a miss or wounding shot on small game, almost an inch off. Not very conductive to consistent field accuracy.

I've had 2 phantoms that could hit coffee cans at 100 metres all day long using the stock sights and pick off 9mm brass at 15m without a problem. Dime sized groups at 20m with this optimus isn't the problem. Needing to exactly duplicate the position used when sighting in while hunting is a problem.

Damn! I must have gotten all the shyt Crosman's. lol

I am new to this forum. No one here really knows me from jack and maybe I am out of place in commenting but I’ll throw my 2 cents in by telling a short story.
When I was a young man I thought I was a sh*t hot shot. No scopes just open sites. My eyes were good then. I joined the army (infantry) and unlike a lot of other people who were in the CAF, that I have talked to, I was not a sniper. (joke) Anyways my weapon’s handling qualifications were good enough that I was assigned to the rifle team for 6 months to compete in the Queens Plate (I think that was what it was called) in the fall, in Ottawa. Man we spent a lot of time on the range. Fired a LOT of 7.62. So long story short I thought I was sh*t hot but I had trouble with consistency. I had tight groups per magazine but whenever I changed mags my POI changed, left, right, centre back to right etc. (sound familiar) The NCO in charge, Sgt Pye, sat with me over a few weeks of firing and showed me a few pointers.
1. Breathing, every time you exhale your sight should align perfectly with the target, if it doesn’t shift body position, not the rifle, until it does. When you squeeze a round off, after recoil, the sight should be exactly back on target
2. Always hold your rifle in exactly the same position when firing. He even chalked the stock, pistol grip and butt plate to help me make sure I was holding the rifle exactly the same way every time.
3. Point of aim. I had this weird anomaly that the further from the target I got the tighter my groups got. I shot better at 1000 yds than I did at 100. The reason, he said, was my point of aim was much smaller at 1000 yards. He put a white paint dot, very small, on the front blade to help me improve my point of aim at 100 yrds. It was all about focus. Aim small miss small is the term I have heard in the last few years.
Sgt Pye improved my scores enough that I was the top score on the team and I could move on. I chose not to, because you can only go once, and I figured that I could improve enough the following year to make a real go of it. Life happens and I never got back. Proof that you should always grab the bull by the horns because you never know if it is your last ride. But I digress.
I haven’t shot in 30 years and I am just getting back into it but these rules/guidelines are helping improve my consistency again. Every week I get better.
If I am out of line please accept my apologies. You don't know me and I don't know you.

I'd say install a new main seal, which you also sand down to get max power, misc other tuning to get the most from it, then either take some preload off the spring or use a lighter one. A scope helps balance the gun out so hopefully you're using one.
If you want details on all this you can email me at chevota at hotmail and I'll send it. The gun can be day/night better when done.

I have been working with my Benjamin Classic .22 lately, it is more less the same gun as your optimus. I did some trigger work and also some work with lube and the spring tuning. With the stock 495fps spring the gun handles very nice and at 10m can hold very tight groups. The stock spring is just a cut off spring that is unfinished on one end so I heated the unfinished end with a torch and ground it down so it is finished on both ends. This made the spring about 1/4" shorter so I put a 1/2" spacer in to give me a tad more preload than stock. The gun shot very nice this way but I would say that there was very little in the way of a power increase. I then installed the pal spring and the gun shot very hard but the accuracy suffered and the overall handling of the gun just was not as nice as with the weak spring. The last thing I have tried is cutting 2 coils off the pal spring. The shot cycle seems a bit better than the full pal spring and it still seems to have quite a bit more power than stock but it is still not as accurate as with the non pal spring. The next thing I am going to try is a utility spring from specialty shooting. I ordered one that has close to the stock dimensions but with .005" thinner wire than the pal spring. I am hoping this spring will give me the happy medium that I am looking for between the non pal spring and the pal spring. I may cut one more coil off the pal spring as well but that will be the limit as it will be as short as I can go with out having to add spacers to keep enough preload on the spring. When I complete the last two options I will report back. But for now I will say that I like the pal spring with 2 coils cut off better than the stock pal spring. IMO the pal spring is just too much for the gun.

Kanuck1958, your advice sounds good to me.

Not out of line at all and great advice to get groups smaller. Consistency is certainly key. Not really my problem though.

From a seated field target position I can consistently print good groups, about 3/4" left of centre. When in a seated position using the artillery hold I can print good groups if I do my part, dead on centre. If I'm standing and using the artillery hold I can print good groups, about 3/4" low. From any one position the groups are quite good. Now change the position of my hand on the stock an inch forward and the groups will still be good but the poi will not be the same as the original groups. The problem is that being in the exact same position as I've sighted the gun in while hunting is an exercise in futility.

Have you tried different pellets, and if you think its too fast try heavier pellets. Also I believe those triggers are crap so you can get an upgraded trigger for them I'm sure. If you want to slow it down a bit cut a coil or two off the spring, there are lots posts on cutting springs, its not hard I've done it several times without any problems.
Check the crown on your barrel, if it doesn't look symmetrical the you mat need to re-dress it and you can check it for burrs with a q-tip, just push it in and when you take it out see if any strands were snagged. These are all things I do when I'm trying for better accuracy as well as practice practice practice.

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When the chips are down, the buffalo is empty.

Yesterday I removed just a hair over 1" of pre-load off by removing the bearing washer that I put in above the top hat and taking off the top step of the big pyramid pre-load spacer at the bottom of the spring. I'll have to wait until the weekend to try it out though. If it's still too much I'll try the full power piston and the detuned Canadian spring and go from there. There's got to be a happy medium in there somewhere.

edit: Sorry, I messed up the quoting. I think this fixes it.



I'm no great shot with a rifle (especially springers), so take what I say with that in mind. What you're describing sounds relatively normal to me - certainly I get a good 1" plus shift in POI going from rested to offhand with some of my rifles. As long as that shift is consistent you can either compensate with you aiming point or adjust the sights. Compensating is easier with a nice mil-dot scope, and adjusting is rather dependent on good quality sights that move in a predictable way.



So the key here is to achieve a repeatable hold, every time. I'm not a hunter, and I can imagine that under the pressure of getting the shot off that's easier said than done. Making sure the gun fits you well is the first step, so that it shoulders naturally and you're not having to search for the sight picture. If necessary, add something to the stock to make it easier to achieve a perfectly reproducible hold. That might be as simple as hockey tape so that you can feel where your supporting hand goes, or it might be something more complex, like adding wood or rubber to give your hand a positive position to locate in.

My "low power" gun has that spacer on the guide removed altogether, otherwise it's a full power 18+ftlb gun. With that one change the power is 9ftlbs. Cocking effort is cut in half too, down to 12lbs. Incredibly easy to cock, very quiet, very tame. So basically you can make any power level you want. Just be wary that the piston catch on the sear can catch the coil spring which can bend the spring.Should make sense when you look at it. There are ways to fix that but I haven't made one that is easy and safe yet so I don't want to post what I did. If your sear catches I have two fix ideas for you if you want.