Question about Chrony Test

[D.A.T]

I have a 77/22 target/ all weather model. I shoot wolf match ammo.

I am want to shoot beyond 100 yrds with it so I decided to chrono my rounds to get the dope. My first 10 round shot group avg. was around 1075 the second 10 shot group was around 1065. For some reason on the next group I was closer then the 2 other shot group by about 3 feet and my readings went up to the high 1070's and mid 1080's. I thought this was really strange due to the small amout I moved forward. I then moved about 1 yard back from my original spot and my readings droped down the the 1050's.

Is this spread normal with less then 2 yards difference in movement? My orginal distance was about 6-10 feet from the chrono.

can you guys give me any insight?

I have not noticed this large of spread when shooting other guns and calibers.

 

[BOLTRIPPER]

Re: Question about Chrony Test

please know that the MV is only recorded at that point between the two eyes........so if you could place the chrono say 375yd down range and manage to place the bullet over the eyes ....thats what the MV is at that range....

and there are chronos for paintball and arrows....etc.....RTFI

 

[One-Eyed Jack]

Re: Question about Chrony Test

You can expect a drop in velocity of 10 to 15 feet/second in the first 10 feet from the muzzle, based on a JBM calculation I just did.

 

[TOP PREDATOR]

Re: Question about Chrony Test

22'S are evil and will drive you nuts, which is the charm of it.
a few yards difference will make that kind of a difference, just as + or - an 1" to 2" of barrel length will. i bet if you move back another yard you'll get around 1040.

the bullet is starting to loose velocity as soon as it leaves the pipe, (sometimes even within the barrel if all the powder is burned up and if any pressure is lost with a bad seal between the lands / grooves and the bullet)

don't forget your dealing with a much slower bullet than your accustomed to.

 

[D.A.T]

Re: Question about Chrony Test

So where should I measure my mv from to get as accurate dope as possible?

The difference in drop between a 1050 and 1080 v is about 1.5 inches at 100 yds with a 50 yrd zero....

 

[sobrbiker883]

Re: Question about Chrony Test

Most accurate dope is real DOPE (data on previous engagements).

A 22 ballistic calculator will only get you close, no matter how accurate your ballistics program is. Keeping track of how much you need to dial at different distances will be better.

 

[TOP PREDATOR]

Re: Question about Chrony Test

sobrbiker883 said it best. even run the numbers you have now in the ballistic computer to get you close, then actually go out and shoot taking notes on your adjustments and final settings for each range to give you a factual data book on your setup and ammo

 

[NOMAD]

Re: Question about Chrony Test

Yes get your self a good data book and keep track of that real world data!!

 

[D.A.T]

Re: Question about Chrony Test

thanx alot guys

 

[TOP PREDATOR]

Re: Question about Chrony Test

good info on this threadhow far should the chrony be from the gun