Groups going from 1/4" to 3"
Was out shooting the CZ 527 Varmint in 223 (1 in 9 twist) yesterday. I was shooting 1/8 to 1/4 inch three shot groups at 100 yards all day. When I went out to 200 yards my group sized increased to about 3 or 4 inches, not just once or twice, but with every group that I shot. Came back to 100 and they were all within 1/4 inch again.
The load I'm using is a 50gr V-Max, 21.9 Gr of IMR 2198, CCI Small Rifle Primer, and C.O.A.L of 2.220. This is a load that I worked up for a 1 in 12 twist rifle, but it shot so well at 100 yds out of this rifle that I just stuck with it. Is it possible that the fast twist of this 1 in 9 twist rifle is over-stabilizing the 50 gr bullet, but only after 100 yds?
I really don't want to have to go to a different bullet because I've had great success with the 50gr V-Max, but as most of my shots on whistlepigs are well over 100 yds I just may have to. Any advice would be greatly appreciated!
Re: Groups going from 1/4" to 3"
50g projectiles are certainly in the realm of possibilities for a 1:9 twist gun. 55-62g is often thought of as the sweet spot for barrels of that twist. I don't think it's the projo alone.
What were the conditions when shooting out to 200? Strong winds? How were you shooting? What was your setup? It sounds to me that it's environmental and not the gun/ammo combo.
What scope are you using? What's the subtensions? Have you chrono'd the ammo for a consistency check?
Re: Groups going from 1/4" to 3"
There was a fairly brisk wind, but I doubt it was strong enough to affect the bullets that much. I was getting some horizontal stringing, and it was actually going into the wind, not like the wind was pushing the bullets. I was shooting off the bench using sandbags. She's topped with a Nikon Monarch 5 3-15. I'm honestly not sure of the subtentions, butit's probably .25 to .375 at 100yds. I have not chrono'd the ammo. It's just odd to me that it shoots so well at 100, then goes to shit at 200. Gonna buy some heavier factory ammo next time I hit the range and see what happens.
Re: Groups going from 1/4" to 3"
Your 1x9 twist is too fast for the 50 gr bullet.
If you shoot at 300 yds or more, your groups will start to resemble shotgun patterns. While it may be accurate at 100 yds, at greater distance, it's start to spin out of control, causing greater shot dispersion.
Take a look at this chart under the heading ".224", to the right of the yellow highlighted column - which is the diameter of your 50 gr. bullet. It shows the suggested twist rate you should be using:
Attachment 97067
Re: Groups going from 1/4" to 3"
Quote:
Originally Posted by
bamboomaster
Your 1x9 twist is too fast for the 50 gr bullet.
If you shoot at 300 yds or more, your groups will start to resemble shotgun patterns. While it may be accurate at 100 yds, at greater distance, it's start to spin out of control, causing greater shot dispersion.
Take a look at this chart under the heading ".224", to the right of the yellow highlighted column - which is the diameter of your 50 gr. bullet. It shows the suggested twist rate you should be using:
Attachment 97067
That's really what I was thinking too. Guess I'll have to invest in some new bullets... Back to load development I guess.
So... change of topic. Anyone know of a good bullet in the 65-75 gr range for poking varmints?
Re: Groups going from 1/4" to 3"
Did you adjust the parallax on your scope (if it has the adjustment) for 200 yards?
If it doesn't have parallax adjustment then it's possible it's fixed for 100 yards, which means you'll can have parallax issues at 200 yards (if you can't keep your eye in the exact center of the exit pupil).
Re: Groups going from 1/4" to 3"
Look here and take your pick! And don't use any "pulled" surplus sh!t for the distances you're shooting...:rolleyes:
https://www.wideners.com/reloading-s...ts/223-bullets
Re: Groups going from 1/4" to 3"
Quote:
Originally Posted by
bamboomaster
I'm a big fan of the Sierra 69 Grain HPBT MatchKing out to 300 yards.
Re: Groups going from 1/4" to 3"
Parallax was properly adjusted. This is primarily a hunting rifle, with shots on groundhogs out to about 450, and I take an occasional shot at a coyote or fox but those are normally less than 150 yds. I would say the vast majority of my shots are under 300. Will a match bullet put a groundhog down humanely at that sort of distance? I have no experience shooting critters with match ammo, and the quick search I did just now turns up mixed results.
Re: Groups going from 1/4" to 3"
Could always try a heavier version of the v-max. I've had good accuracy with the 60gr v-max's out of an ar. My current load is 25gr 4895 with a cci primer.
