How much variation in speed with an Anschutz 2002?

[Sparks]

So I bought a chronograph and used it tonight. 20 pellets though, and an average of 176.78m/s off the FrankenRifle. But the spread was 2.4m/s over that group, from 175.7 up to 178.1, and this was after firing a few shots in the beginning to get the rifle 'warmed up'.
I don't suppose anyone knows off the top of their head if that's a normal level of consistency or if I have a problem on my hands?

[Shooting Kiwi]

I don't know the answer to your question. The problem is that there are (at least) two possible variables - the rifle and the pellets. You might look at the variability with different brands, diameters and weights of pellets. Utter confusion is achievable...

[sbrmike]

I only ever tested two 2002's and they both held within 5 fps over 20 shots. What we did notice was if you pumped and then shot fast it varied a bit more than that, but if you pumped it and waited at least 10 seconds before shooting it was much more consistant. We even pumped them and then let them sit 30 minutes and the velocity was right in there the same as if we waited 10 seconds. I don't rmember the velocities but do remember the extreme spread which was 5 fps (feet per second).

[Levergun59]

That is not a good extreme spread especially with an airgun. Your extreme spread is 2.4m/s. Airguns have the longest barrel time of all the firearms, so extreme spread is critical to accuracy. My Palma rifle in 7mm mag has an ES of 6fps at 3000ft/s. That is exceptionally good for a smokeless round but critical for elevation deviancies at 1000yds with an exceptionally short barrel time. Most Palma rifles are definitely under 20fps for an ES. Blackpowder 1000yd shooters can get under that with an ES of 4fps. Black powder is the most consistant propellent on the market in a skilled reloaders hands. It has to be as the heavy slug has a lot of barrel time and considerable recoil to manage consistantly. What is more amazing is back in the 1890's the black powder was much better than anything made today, with 100's of brands to choose from. Sorry for the ramble.
Chris

[robf]

sparks, you're going to get chronoitis if you don't be careful ;-)

that's not that bad... what's the shot to shot like?

remember you are shooting at 10m, not 50. I've seen good grouping rifles with shot variation just the same.

What you need to do is first assess if the chrono is reading right... distance from muzzle and consistency of position and lighting (except for CED M2 IR's) all need to be constant... else you will see variations.

next is the ammo... get more than one type and more than one batch.

also check fill pressure, as even though the 2002 is reg'd, it will probably have a sweet spot and towards the end or start of a charge you can see more variation and sometimes even a trend.

things like sizing pellets and checking for damage will reduce variation... forget stated head sizes, i have a head checker and for the domed variety they are a nonsense. I would not expect flat heads to be much different... only the expectation to be so.

my walther running at about 800 fps will vary in extreme about 12 fps over a charge, 8 fps shot to shot... i can halve that by manually sizing and weighing, sorting out nicked pellets.

i would say play with pellets first before getting the rifle checked, but you will need to take it to someone who knows what they are doing, and who has a reg checker for a start. But i suspect pellets could be better... and perhaps the onset of chronoitis.

does it actually group or are you noticing a vertical spread?

[brucebacon]

My daughter's 2002 had a similar problem. Turned out that the regulator was bad. According to the gunsmith that fixed it (Chuck Gartland) they need replaced every 2 to 5 years. Replacing the regulator cost around $300.

[robf]

regs can be checked with a reg checker, else it could be seals on the rifle.

it shouldnt need a new reg, you can have them rebuilt/reset if you know the right man.