[Waffen]

I have been struggling to find a load for a CZ 550 Varmint in .22-250 that will one hole. I have tried multiple different powders (IMR 4064, IMR4350, IMR4130, H380, Varget) and different bullets of different weights. I can't figure this thing out for the life of me. I can only manage to get at lowest about .4 and on average I would guess .75 - 1.0 groups. I have had another shooter who has more shooting ability in his pinky finger than I have in my entire body shoot. He was still only able to do slightly better.

The only thing I can think of is seating depth. I know the max depth in the books is 2.350. I have seated out to 2.375 with no real affect on groupings, so tonight after another range session with the same results I decided to just barley seat a bullet and see if I could chamber it and "seat" the bullet on the rifling, then back it down .005. Much to my surprise I was unable to do so. The bullet was molly coated and I did not see any rifling marks on it at all, and I did not feel any resistance when trying to chamber the round. I then measured the round and it was at 2.472 witch surprised the heck out of me.

My question is, do you think I could seat the bullet out to 2.4 without any negative pressure signs? If I do get signs of excess pressure, would you think it would be catastrophic? Also, what is the max you have heard a .22-250 being seated at?

Any input on how to increase accuracy would be appreciated.

[steve4102]

I have a CZ 550 American in 9.3x62. Out of the box the bolt handle would hit the stock when closed. I did a little sanding until the handle was clear, she's a real shooter now.

[Dave P]

My question is, do you think I could seat the bullet out to 2.4 without any negative pressure signs?


With a nominal powder load, seating into the lands should not cause problems. Pressure may even be lower due to the enlarged burn space for the powder.

I did not see any mention of bullet types; you have tried a couple/three of top quality brands, haven't you? Cheap bullets do not perform.

Dave

[Rockstar]

Spend a few bucks and get the Stoney Point tool with the dummy case. Accurately measure o.a.l., relative to the lands. Seat .010" off the lands and see what your o.a.l. is. Loading longer won't increase your pressure; it'll reduce your pressure, unless you're hard into the lands.

You've mentioned using a lot of different powders. How much load variance are you using with the different powders? Are you using data for moly bullets, which, of course, require more powder?

[Lennyjoe]

What type of barrel? Is it a heavy varmint or a standard barrel? Has there been any other work done to it or is it a bone stock rifle?

I have a Savage 12FLV in 22-250 with a heavy varmint barrel and it's putting out .5" @100 with 50gr V-max and Varget. I'm in the process of trying H-380 and 55gr bullets at this time.

Also, which type of bullet are you using? Try a match bullet if your using varmint rounds.

My chamber measures 2.500 with 50gr V-max bullets. I don't have a Stoney point set up yet but use the old method of magic marker, fired brass and bullet. 2.350 is what the book calls for but as I flirted to 2.400 I seen the groups start to tighten up a bit.

[ocabj]

You need to get a bullet comparator so you can measure the length of the cartridge based on the ogive.

[Waffen]

I am using the factory 26 inch bull barrel. There have been no modifications to the rifle with exception to setting the trigger down to about 1lb area. I use a coated rod/jag for cleaning. After each cleaning I use wipeout 3 to 4 times until I get clean patches.

My load spectrum varries greatly. I have loaded all my 50gr bullets to fly at 3400fps all the way up to 3900.

The 55gr's I have loaded from 3200fps to 3600fps.

Bullets I have tried so far:

Hornady 50gr Vmax Molly coated
Hornady 55gr Vmax
Speer 50 gr Molly coated match HP
Speer 52gr Match HP
Sierra 52gr BTHP Match King
Nosler 50gr Ballistic Tip
Nosler 55gr Ballistic Tip

I use Winchester cases that up to now have 2 loadings through them. I use Federal 210M primers, and have tried WLR with no change.

When I shoot I am shooting from Caldwell front and rear bags, or off my Harris Bi-Pod and caldwell rear bag.

[Waffen]

I picked up some Winchester 760 powder today. Has anyone had any good luck with this in a .22-250. I figured it was too slow burning, but somone on AR swore by it. Anyone here have anything to say about it?

[Ky Larry]

My CZ-550 Varmint had the same problem. It just wouldn't shoot as well as my Ruger 77V. I free floated the barrel and solved the problem. Hope this helps.

[Rockstar]

Can't imagine that you'd have a lot of success, mixing moly with naked bullets. Did I mention the Stoney Point tool? ;) You don't want to "lay in" moly over copper fouling. You also won't get good groups from moly bullets unless you pretreat the barrel or shoot 15-20 rounds of moly bullets to "lay in" the moly from the throat to the muzzle.

[RecoilRob]

If you aren't already checking runout, that would be worth doing. If they aren't starting straight, they don't fly as well.

The RCBS Case Master is inexpensive and mine proved to be illuminating when I was on the same quest as you.

[swifter]

:( I've had better results varying seating depth than jacking around with powders.

You WILL need a comparator, and a reliable dial caliper. Seat a bullet in an unprimed, uncharged case and chamber it carefully. Extract it carefully, and measure it. You need the comparator to get a measure to the same place on the ogive each time. (Measuring to the tip does not give a consistent measure.) This measurement is your "jam Length". Start 0.005" shorter. Work back in 0.005" increments.

Determine which powder & charge gave the best groups with that bullet. If the charge is less than maximum, load three rounds 0.005" short of your jam length, then three more, 0.005" shorter and keep working back thru at least five iterations. Why 3 rounds? If 3 won't snuggle up in one hole,5 probably won't either... :(

This is the method to adjust seating depth... Which may not be your problem... Things that occur to me are: Wind flags. Awful hard to get 1-hole groups without 'em. Others mentioned bedding. And again, this is a factory rifle. If it will shoot under 0.5" consistantly, you have a jewel. Be content... :evil: 'Twas me, I'd ship it to my favorite riflesmith for his "accuracy package"... But thats me... :D

Tom

[rick_reno]

We're having good luck in a Cooper Arms 22-250 with 36.5 grs of H380, Sierra 50 gr Blitzking bullet, Federal Bench rest primers. OAL that has worked well is 2.505. Groups shot in the wind late last week were under .5 MOA. We're trying some at 2.500 tomorrow.

[Waffen]

Well, I think I found my powder. The Winchester 760 put 5 rounds into a nickle-sized group @ 100 yards, and I have the "shoot and see" to prove it! I will get pics up ASAP.

I loaded 10 of each 39gr 40gr and 41gr.
50GR Molly Coated V-Max
Fed 210M Primers
Winchester Brass

Probaby 90 outside, with a light 10mph wind.

For some reason the 39gr and the 41gr were the best shooters, but the 41gr was a little tighter. I am going to seat these bullets out to 2.400 next time and see if it tightens up a little bit.

I am going to do the same now with different bullets and see what happens. A friend suggested that maby the longer 26' barrel would like a slower burning powder, looks like he was correct. I may try some IMR-4350 out too.

Either way, I have about 100 cases in the tumbler now, so it shouldn't be long until I get to find out.

[~z]

I realize I havent been around this site long enough to gain any capital, But I'll thow in my $.02. Figure the seat depth first. Any suitable powder, any suitable bullet. The length (measured from the ogive) that provides the best group is the length to use in this rifle. This length measured from the ogive stays and the rest changes. Even if the best group is 2". Now vary powder charge/powder brand...This order will save time and $. You can get there by other methods, but in my experience, this is the best way. If anyone knows of a better way, let me know, I'm here to learn.