Accuracy and reasonable expectations

[jfm30204]

I have been playing around with the tuning specs on my syn-rod - not really getting anywhere, but that's another issue - and one thing I have been relatively unimpressed with is the accuracy over 29 yards. Surely, every now and then I will get a really good group for 6 of 8 shots, but the other two will spread the group to nearly 1". The rest of the time, I am usually in the .75" to 1" range. I am shooting JSB Exacts from a shooting stand and am careful to adjust out the parallax on the CenterPoint 4-16x40 scope.

Now it seems to me that, if a rifle will not reliably shoot .5" to .75" groups at 50 yards, given the small target sizes of squirrels, pigeons, etc., then it would be unwise to attempt such shots at ranges of 50+ yards. I want .5" groups, but, as my grandmother used to say, if you want in one hand and spit in the other, you should not be surprised at which fills quicker.

You're probably guessing that there's a question here somewhere, and you are correct: What is a reasonable expectation of accuracy in this rifle at, say 50 yards, consistently, once the final tune has been found?

[RayK]

Have you shot a string over the chronograph? Do you have a good shot curve? Have you selected out your sweet spot of shot string where the velocities are within a small extreme spread?

You want to use your shots that are within 3% for best groups at distance.

Most 25 M-rods seem capable of .5" center-to-center groups at 50 yards with JSB Kings.

If you had a 22 caliber M-rod, I'd say what you have is typical if not better than typical.

What, if anything, have you done to your gun since bought new? Did you clean the barrel? How? Did you modify anything or change your settings? What are they now? I remember you had some trouble with the VMS adjustment. Is that sorted out now? Did you remove the shroud? If so, how did you re-install it? Is the shroud touching the breech?

There are so many factors that go into accurate shooting. Is your crosshair fine or thick? 16X is pretty low magnification for precision shooting at longer range. I use 24X. I know it is possible with lower mag, but it is also easier to be off by just a tiny bit with a thick reticle or lower magnification.

Ray

[jfm30204]

Wow!

Have you shot a string over the chronograph? Do you have a good shot curve? Have you selected out your sweet spot of shot string where the velocities are within a small extreme spread?

You want to use your shots that are within 3% for best groups at distance.

Most 25 M-rods seem capable of .5" center-to-center groups at 50 yards with JSB Kings.

If you had a 22 caliber M-rod, I'd say what you have is typical if not better than typical.

Yes, I have. Several hundred, but no nice curve yet. Pretty much stumbling in the dark. I was about to ask for help. Ran out of JSBs, though, so awaiting new shipment.

What, if anything, have you done to your gun since bought new?

De-floated the shroud via cut piece of rubber like inner tube. Fooled around with the settings.

Did you clean the barrel? How?

After several hundred shots. Carefully with nylon brush from the breech using JB bore compound and then a bit of silicone oil until patches came out clean. Didn't notice much difference.

Did you modify anything or change your settings?

Oh, yeah. Tried Hill's: (spring, throw, valve) 3.5, 0, 5.5, yours: 6, 3, 5.5, and some settings using the gen 2 25 cal nomograph. Nothing interesting with any of it. So, I'm going to start over with the new shipment of JSBs and ask for help.

What are they now?

Darned if i know. I think 4, 3, 3.

I remember you had some trouble with the VMS adjustment. Is that sorted out now?

Yes.

Did you remove the shroud? If so, how did you re-install it? Is the shroud touching the breech?

Yes, I did. Reinstalled correctly, de-floated it, and yes it is touching the breech.

There are so many factors that go into accurate shooting. Is your crosshair fine or thick? 16X is pretty low magnification for precision shooting at longer range. I use 24X. I know it is possible with lower mag, but it is also easier to be off by just a tiny bit with a thick reticle or lower magnification.

I tried once at 50 yards, and the results were way less than spectacular, but, since I hadn't tried to tune it at that point, I wasn't so very disappointed. Everything since has been at 29 yards, the longest I can get in my back yard with any degree of privacy.

Thanks so much for the input. As I said, once I get more ammo, I intend to start from scratch and ask for help. One more thing that was a huge problem is that the Hill pump gauge would read 3000, and the gun gauge would read about 3600, so I was never sure just what the correct pressure actually was. I have since changed the gun gauge to a McMaster-Carr version, and it now agrees with that on the pump. That's a big plus.

[RayK]

De-floated the shroud via cut piece of rubber like inner tube. Fooled around with the settings.

I'd take that out. See how it is shooting floated first.

After several hundred shots. Carefully with nylon brush from the breech using JB bore compound and then a bit of silicone oil until patches came out clean. Didn't notice much difference.

Silicone oil in the bore seems like a bad idea to me.

Oh, yeah. Tried Hill's: (spring, throw, valve) 3.5, 0, 5.5, yours: 6, 3, 5.5, and some settings using the gen 2 25 cal nomograph. Nothing interesting with any of it. So, I'm going to start over with the new shipment of JSBs and ask for help.

You should have gotten nice shaped shot strings with one or both, so something is not right. Was that with all stock parts including the hammer spring?

Yes, I did. Reinstalled correctly, de-floated it, and yes it is touching the breech.

I've done best with a gap between the shroud and the breech, so they should not touch. A very small gap is all you need. I also lube the o-ring round the front shroud mount liberally with silicone grease to prevent bind-up. De-floating only helps with some guns and I've seen it make accuracy worse in others.

Ray

[FuzzyGrub]

I'd first tune the gun to get a nice flat 40FPE string of 16 shots. The Gen II is capable of some very low Es strings. While this low Es is not necessary for the next step, it would still be required for moving back out to 30yds and beyond.

Next, prove that your accuracy is good at 10yds. No need to reach out farther unless you have a single small hole, not much larger than a single pellet diameter. This short distance will take out the wind and other variables, that crop up at distance. If you see an issue at 10yds, it is also easier to diagnosis and isolate. No need to zero at 10yds, just interested in the group size, but poi should be about 1" below aim point.

[jfm30204]

Ray,

I'll make those changes and clean the barrel again in the mean time. Then, when the JSBs come and it looks like we'll have some good weather, I'll post asking for help.

Also, another strange thing is that this rifle will not shoot H&N Barracudas at all. I mean it'll get 'em out of the barrel, but then you have 1" plus 29 yard groups. That just ain't right, is it?

Thanks a heap. Until then, I'll be salivating while dreaming about under 1" 50 yard groups.

Jere

[jfm30204]

I'd first tune the gun to get a nice flat 40FPE string of 16 shots. The Gen II is capable of some very low Es strings. While this low Es is not necessary for the next step, it would still be required for moving back out to 30yds and beyond.

Next, prove that your accuracy is good at 10yds. No need to reach out farther unless you have a single small hole, not much larger than a single pellet diameter. This short distance will take out the wind and other variables, that crop up at distance. If you see an issue at 10yds, it is also easier to diagnosis and isolate. No need to zero at 10yds, just interested in the group size, but poi should be about 1" below aim point.

Thanks. I'll try that.

[caniborrowsomeammo]

Ray,



Also, another strange thing is that this rifle will not shoot H&N Barracudas at all. I mean it'll get 'em out of the barrel, but then you have 1" plus 29 yard groups. That just ain't right, is it?



Jere

Means your barrel doesn't like those pellets. At least at this time.
Silicon in the barrel may not have been a good idea.

[SHOOTINIT]

How does it shoot without shroud on?

[jfm30204]

How does it shoot without shroud on?

I don't know. I'll have to try that and see. The problem is that I am in a neighborhood with close neighbors on both sides, so I'm not quite sure how I will work that out. Good question. Thanks.