Accuracy and reasonable expectations

[jhm757]

It does seem something is amiss most .25 Mrods are very accurate including mine!

One thing I thought about though is the wind. I shoot at 30 yds allot in my yard and on a windy day it can really mess with your groups even at the fairly short range of 30 yds.

Is the area you are shooting in windy?

Does accuracy get better on a calm day?

Jim - jhm757

[jfm30204]

It does seem something is amiss most .25 Mrods are very accurate including mine!

One thing I thought about though is the wind. I shoot at 30 yds allot in my yard and on a windy day it can really mess with your groups even at the fairly short range of 30 yds.

Is the area you are shooting in windy?

Does accuracy get better on a calm day?

Jim - jhm757

No. Very little wind, and the area is fairly sheltered, but we'll see.

[jfm30204]

Yeah if you have 600 shots through after cleaning, it is starting to sound more like a barrel problem. Bummer. Call Crosman maybe? Ask for a replacement? Or possibly just buy a new barrel?

Ok, have you checked the crown of the barrel for damage? Have you checked the baffles to see it you might be clipping one on the way out?

I checked the baffles, and I do not see anything obvious. The crown looks okay to me, but I'll post some pics when I get the chance. That plus a 10 yard 5 shot group.

Someone suggested I try a group without the shroud, and I can't do that in town. W/o the shroud, this rifle is LOUD. The JSBs should come today, so I will do it as soon as I can. I have a friend just a couple of miles out of the city who said that I can do it at his house.

So the game plan is this:
1. I will post the crown and 10 yd group photos as soon as I can

2. I will try some 29 yd groups without the shroud and post the results

3. I will carefully clean the barrel again and run 50 or so rounds through it

Then, hopefully with the advice of this group, I will decide whether to continue with tune attempts or do something else. If we go on to tuning, then I will create a new thread to begin from scratch.

Needless to say, I have really, really appreciated all of the help thus far!

[FuzzyGrub]

I assume that means you think the 5 shot groups are good. Just make sure you shot the same number of rounds that created flyers at 30 yds. Also, make sure you can repeat "good" results. Shoot at least two full strings.

You should at least chrony what your current string is before going back out to 30yds.

[jfm30204]

I assume that means you think the 5 shot groups are good. Just make sure you shot the same number of rounds that created flyers at 30 yds. Also, make sure you can repeat "good" results.

At this point, the idea was to see if can get one hole at 10 yards. I wanted to shoot enough to tell the story but not so many that the area of the target would be destroyed. I thought 5 was just about right for that.

Shoot at least two full strings.

Not sure what you mean by string. Until velocity begins to tail off and time to pump again? One magazine?

You should at least chrony what your current string is before going back out to 30yds.

It seems a bit early for that. I had envisioned dragging the chrony out for the tuning phase, starting from scratch with some setting or another suggested by the group.

[Bob La Londe]

I don't know if it applies on the .25's barrel, but my .177 seems to lead foul over time. When its clean it shoots 10.5 Crosman pellets fairly well, but after a while it shoots bigger and bigger groups. Then I switch to copper jackets and the groups start to shrink again.

[PB_Matrix]

Try a differnent scope if you can borrow one, just to eliminate that CP scope as a problem. There is a reason those scopes only cost $67 at Wal-Mart.

[FuzzyGrub]

You should at least chrony so you know what your Es is between what pressures. Normally, a tuned 25 cal would have 16 shots in a string. It needs to be near perfect at 10yds to be good at 50. But, being perfect at 10, does not mean you will be good at 50. A "fat" hole at 10yds would tell me it won't be good at 50. The biggest variable at distance shooting, is the shooter. Chrony would show if you have large variable of peak/valleys, that might indicate a hammer/sear/ tube interface issue. sticking hammer.

It is best to keep a very methodical approach, go slow and be sure at each step.

Scopes: Many scopes will be at or near max down elevation on airguns. At this position, most will not hold zero well. If your poi is 1" below bull, raise up an 1" to see if it improves. Many of my scopes are shimmed in the back so I am not at or near max.

Mag: Load single shot. Mags can cause pellet scraping or deforming of pellet on bolt closure.

Shroud: Remove shroud and shroud mounts. Verify that the bare barrel can group well.

Breech set-screws, too tight?, too loose?

Is it related to pressure changes?

As you move out in distance, make sure pellet is staying vertical, not shifting or spiraling. Map out in 10yd increments. A flashlight on gun at dusk can make spiraling easily visible.

[jfm30204]

Here's the result, with shroud, at 10 yards. Seems clearly not what would be expected. Tomorrow, I hope to try it without the shroud.

10_yd_groups-480x640 by jfm30204, on Flickr

[RayK]

What is your aim point?

When I'm shooting for accuracy, I like a very precise small target that is off my point of impact (maybe just above it), so it does not get destroyed as you shoot. When your POI is the same as your POA, the hole grows as you shoot the group so it gets more difficult to aim precisely for following shots.

Are you shooting indoors or outdoors? There is always some wind outdoors.

Indoors at 10 yards, I expect all the pellets to be through the same hole if the guy is accurate.

Ray