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PostPosted: Tue Apr 25, 2017 2:46 pm 
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Joined: Sat Sep 03, 2005 9:25 am
Posts: 3432
Location: Ontario, Canada
We all know about springers being more of a challenge to shoot accurately but sometimes I like to test things to see for myself. I have two Crosman Optimus rifles that provide a great testing comparison. Yes, I have a PAL and have been licensed since 1980.

One Optimus is a detuned Canadian version with the 170mm piston but I installed a Crosman B4 mainspring (33 coils, .118" wire). This rifle shoots 630fps with 8.44gr JSB Exact pellets. This sweet shooter is not hold sensitive at all. When shooting from 20 yards the point of impact stays the same whether I'm offhand shooting, shooting off a rest without shoulder contact, or even holding the rifle with shoulder contact and the back of my forearm hand resting on a sandbag. I completed the testing several times and POI does not move any noticeable amount.

The other Optimus is a full power version with 150mm piston. I detuned this rifle to 770fps with the 8.44gr JSB Exact. This was accomplished by keeping the 36 coil .122"wire mainspring but reducing the spacer length for almost no preload. This rifle is hold sensitive if you switch between holding styles. The POI on the target is highest when I benchrest without any shoulder contact. The POI drops 1" at 20 yards when I hold the rifle with shoulder contact and the back of my forearm hand resting on a sandbag. The POI drops another inch when I shoot offhand. I was still able to keep a 10-shot offhand group at 20 yards that was a hair over an inch. The rifle is quite accurate but the POI moves up/down by up to 2" @20yds when shooting styles are changed, unlike the 630fps version. It would be interesting to see the results if I up-tuned the 770fps rifle to 900fps with the OEM spring spacer.

Both rifles are accurate and have tested at 1/2" benchrest groups (5-shots) at 20 yards, many times. I tested the heck out of these and still plan to continue out to 40 or 50 yards when the weather cooperates.


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PostPosted: Tue Apr 25, 2017 6:59 pm 
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Joined: Sun Apr 23, 2017 4:10 am
Posts: 61
TCooper wrote:
Both rifles are accurate and have tested at 1/2" benchrest groups (5-shots) at 20 yards, many times.


As far as I know that is not super-accuracy for a springers. Top spring rifles (let's say HW97, TX200...) can do something like 1/4" in the same conditions. My RWS 34 was doing 1/2" groups at 30m (~33 yards).
And, in my experience, the hold it not always shifts the point of impact. More often it alters the size of a group.

_________________
Rifles: Horhe Jager .22 (LW barrel, 4500psi tube), Mp-512, Mp-60
Pistols: 46M, Zoraki HP-01 ultra, 2240, baikal drozd.


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PostPosted: Tue Apr 25, 2017 8:17 pm 
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Location: Ontario, Canada
ShurikMur wrote:
TCooper wrote:
Both rifles are accurate and have tested at 1/2" benchrest groups (5-shots) at 20 yards, many times.


As far as I know that is not super-accuracy for a springers. Top spring rifles (let's say HW97, TX200...) can do something like 1/4" in the same conditions. My RWS 34 was doing 1/2" groups at 30m (~33 yards).
And, in my experience, the hold it not always shifts the point of impact. More often it alters the size of a group.


I guess I should have explained the Optimus a bit more. The cost for this budget priced Chinese springer rifle is only $89.00 USd with a 4X scope and mount included. It's not a field target rifle to be compared to a TX200 or HW97.

When I test for group size I typically shoot 5 to 10 groups and repeat the process on several different shooting days. This way I know if a small group is typical. The Optimus has shot 1/4" for 5 shots at 20 yards but that is not typical.

I still consider 1/2" at 20 yards to be accurate for a sandbagged cheapo rifle with a cheapo scope and 53 year old eyes steering the gismo. I did not use the adjective "super" to describe the accuracy. Younger eyes, a better rest and better scope with high magnification might squeeze things down a bit more.

Your RWS/Diana 34 is a great shooter! My HW30S would only average 5/8"ctc at 30 yards and I thought that was acceptable ( .58, .70, .60, .79, .56 - ave = .65” ctc). The same rifle averaged .16"ctc at 10 metres, although the best group for the 10 groups at 10m was .09"ctc. Your RWS/Diana-34 must consistently do tiny little ragged holes at 10 metres. That rifle is a keeper for sure.

Here are some actual test results for my Optimus.

5-shot ctc groups @10 metres
JSB Exact (8.44gr) – .26, .26, .31, .20, .19, .32, .16, .18, .19, .22 = .23” ctc ave

5-shot ctc groups @20 yards
JSB Exact (8.44gr) – .44, .63, .26, .60, .57 = .50” ctc ave
JSB Exact (8.44gr) – .47, .50, .38, .62, .42, .61, .53, .49, .66, .63 = .53” ctc ave

You may have missed my point in comparing the rifles. The purpose was to show how a light-weight, budget priced, high power springer can be more sensitive than the same rifle that is set to a low power. I was not trying to prove that the $89 rifle was a match quality rifle. Sorry if I created some confusion.


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PostPosted: Wed Apr 26, 2017 2:49 pm 
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Joined: Sun Apr 23, 2017 4:10 am
Posts: 61
Very reasonable!

But in other hand, the price of a rifle is not always a key factor - because you have to pay once. Can't imagine buying the same rifle every year. And once you afford a good expensive rifle - you're done.

Missing my 34. Sold a couple years ago... :?

_________________
Rifles: Horhe Jager .22 (LW barrel, 4500psi tube), Mp-512, Mp-60
Pistols: 46M, Zoraki HP-01 ultra, 2240, baikal drozd.


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PostPosted: Wed Apr 26, 2017 7:13 pm 
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Joined: Wed Jan 05, 2011 12:35 pm
Posts: 6089
Location: P.G. B.C.
TCooper wrote:
ShurikMur wrote:
TCooper wrote:
Both rifles are accurate and have tested at 1/2" benchrest groups (5-shots) at 20 yards, many times.


As far as I know that is not super-accuracy for a springers. Top spring rifles (let's say HW97, TX200...) can do something like 1/4" in the same conditions. My RWS 34 was doing 1/2" groups at 30m (~33 yards).
And, in my experience, the hold it not always shifts the point of impact. More often it alters the size of a group.


I guess I should have explained the Optimus a bit more. The cost for this budget priced Chinese springer rifle is only $89.00 USd with a 4X scope and mount included. It's not a field target rifle to be compared to a TX200 or HW97.

When I test for group size I typically shoot 5 to 10 groups and repeat the process on several different shooting days. This way I know if a small group is typical. The Optimus has shot 1/4" for 5 shots at 20 yards but that is not typical.

I still consider 1/2" at 20 yards to be accurate for a sandbagged cheapo rifle with a cheapo scope and 53 year old eyes steering the gismo. I did not use the adjective "super" to describe the accuracy. Younger eyes, a better rest and better scope with high magnification might squeeze things down a bit more.

Your RWS/Diana 34 is a great shooter! My HW30S would only average 5/8"ctc at 30 yards and I thought that was acceptable ( .58, .70, .60, .79, .56 - ave = .65” ctc). The same rifle averaged .16"ctc at 10 metres, although the best group for the 10 groups at 10m was .09"ctc. Your RWS/Diana-34 must consistently do tiny little ragged holes at 10 metres. That rifle is a keeper for sure.

Here are some actual test results for my Optimus.

5-shot ctc groups @10 metres
JSB Exact (8.44gr) – .26, .26, .31, .20, .19, .32, .16, .18, .19, .22 = .23” ctc ave

5-shot ctc groups @20 yards
JSB Exact (8.44gr) – .44, .63, .26, .60, .57 = .50” ctc ave
JSB Exact (8.44gr) – .47, .50, .38, .62, .42, .61, .53, .49, .66, .63 = .53” ctc ave

You may have missed my point in comparing the rifles. The purpose was to show how a light-weight, budget priced, high power springer can be more sensitive than the same rifle that is set to a low power. I was not trying to prove that the $89 rifle was a match quality rifle. Sorry if I created some confusion.



Nothing wrong with those groups from a fairly inexpensive rifle, in fact, they are GREAT!

I found my 97 to cut group sizes in 1/2 with a switch to 4.51mm pellets - Cometa. Standard 4.51mm Exacts did not shoot as well. It also likes Predators - EVERY one of my rifles likes PREDATORS, 2/.177, 2/.22's and the .25-0 2 springers and 2 PCP's & a CO2.

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Daryl


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PostPosted: Sun Apr 30, 2017 9:14 pm 
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Joined: Thu Feb 02, 2006 11:35 pm
Posts: 3099
Location: Alberta Canada
Spring guns are funny beasts. If it's not the firing cycle that's the issue it's the trigger control .
IMHO simple solution to deduce all other aspects. As you exhale and squeeze the trigger close your eyes. If you are within less then an inch of opening your eyes after the gun shoots and being on target. Is not you it's the gun. Now is it the fireing cycle or is it the shooter upon trigger control. ...hmmm Think about it.
Then try it.
Await your responses.
Another aspect to consider are those shooting thru scopes. (Applies to any weapon) Shoulder the weapon to shoot. Now close your eyes and do the same. Is you POA (point of aim) the same as point of impact (poi)? If not then eithers it the scope or the height of rings are an indicator of the issue.
If the gun and optics/ sights don't fit your shooting style. DON'T expect good accuracy or merricles (lol spelling ). That your accurate and on target for that gun. JMHO other factors play an immense part of the picture here.
Think about this before your response.

Regards Whitewolf

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May the cry of the pack be with you upon your hunt

Whitewolf


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PostPosted: Mon May 01, 2017 7:59 am 
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Joined: Sun Nov 30, 2014 8:22 pm
Posts: 286
Location: Hill Spring, Alberta
I read an article about point of aim and point of impact quite a long time ago.

The lady advised one to be prepared to shoot but with the safety on, aim at the intended target, close one's eyes and take three slow breaths. When eyes are opened what one will see across the sights is the "natural" point of aim. The object then is to change body position to make the intended and natural points of aim the same.

I do it all the time and it really works.

I agree with the trigger control issue too. All of my triggers (except T-06 on Diana) have been modified into 2-stages and/or had the internals polished so that they operate smoothly and easily. All the aiming in the world doesn't help if a stiff or unpredictable trigger makes one pull the gun off line.

I love shooting my springers (which most of my guns are) and I try to make the artillery hold the same for each of them. I've never tested for sensitivity, so I'll just follow this thread.

The artillery hold also transfers easily to my pumpers and C02 rifle.

Peter :D


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PostPosted: Sat May 13, 2017 10:02 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1278
Location: United States
If you're really into finding out the cause I'd swap the spring/piston assy between the two and see what happens.
My guns are generally not very hold sensitive but I don't shoot them from a firm rest either b/c I of what usually happens. I do have one crosman that I did similar which is a full power with the spacer removed and it's quite gentle. I think I told you about that one, and it has a suppressor so it's rather quiet, for a springer. I'd wager $5 it works better than your 170mm, especially if I dropped power down it its level. I'd bet mainly b/c I'm willing to lose $5, but I do think the longer stroke would work better. Too bad we don't live close, we could tinker.... Better yet you could motivate me to tinker period b/c I've haven't done squat in over a year.
But post whatever you do, I'm still very curious....


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PostPosted: Sun May 14, 2017 6:54 am 
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Joined: Mon May 26, 2014 1:08 am
Posts: 480
Location: Thunder Bay
I have a cheap Springer that is phenomenally accurate. I watched our OP Todd Cooper shoot a .167" group at 20 meters with it off bags. It will do that every time you ask it to. It also does the same thing Todd's full power Optimus does when switching between bags and offhand. Poi moves vertically.
IMHO, the slower moving piston imparts less energy to recoil to overcome the inertia of the gun when held offhand, resulting in less overall movement of the gun before the pellet leaves the barrel as compared to when the gun is supported by bags. I have a detuned Chinese B3 (520fps) that doesn't change poi. Todd remarked when he shot it "Jeez, it doesn't even move".
Btw -that cheap accurate Springer is a lowly crosman fury Springer refurb! +20k shots, well tuned but still using the original breach and piston seals! Original plastic alignment washers too! Detuned to 13fpe with a stock full power spring and the large spacer cut in half to reduce the preload. I shrink tubed the stock guide, soft bedded it and did a home trigger job. I'm going to take the old master's advice and do as Todd said, "Don't touch anything on that rifle. Just shoot it."
It seems that the more the fpe exceeds the weight of the gun, the more recoil effects you can expect from a Springer. You can mitigate the effects somewhat, but you can't fool physics.

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2 lathes and lots of scrap metal.

I'm not multitasking. I'm doing something else until I remember what I was doing.


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