I have been trying to get accuracy for ~10 years, but of 50 bolt action center fire rifles, none would average better than 2" for 5 shot groups at 100 meters, and my AR15's were stuck at 1.4".

The latest gun I built is a .257 Roberts Ackley Improved, and it has averaged .87" for the first 14 groups with 72 gr bullets, and I have yet to vary the powder charge or bullet seating [49.4 gr IMR4895, 3.406" OAL meaured with Sinclair ogive nut].

One trouble with accuracy, is that it is the product and/or sum of so many variables, I don't have time to sort out what is, or is not, required.

Some things were new for me with the .257RAI rifle:
1) Factory hand lapped barrel [light varmint taper Lothar Walthar]
2) Ackley Improved chamber
3) Lapped the lugs
4) controlled bolt position in receiver
5) removed the recoil cross bolt in the stock and filled the hole with epoxy
6) put moly grease on the threads to screw on barrel
7) glass bedded the action with the pour method
8) glassed under 4" of the barrel
9) prepped the brass with steel wool on a bore brush to smooth out inside of neck
10) measured throat depth with ink on a dummy round seated shorter until no ink was scratched
11) controlled seating depth consistency with Sinclair bullet comparitor
12) used a competition Forster die set
13) used a concentricity gage, and it taught me to get rid of expander ball
14) used WLR primers instead of CCI200
15) moly burnishing in a virgin bore, and shoot only moly bullets
16) checked the wind condition on the weather site before driving to the range and only went when wind was 3 mph or less

Some things I did for this rifle, but I have done before with other rifles:
1) built on a VZ24 action and cut threads to 55 degrees
2) lathe trued the action large ring to the receiver bolt bore
3) lapped the action inner stop ring true to the large ring
4) used the original military stock
5) glass bedded the action
6) Did a trigger job controlling the force [down to ounces], travel, and over travel
7) tightened the forward screw more than the rear
8) prepped the brass with mouth chamfer
9) prepped the brass with weight sorting
10) Berger moly bullets
11) used a 40X Leupold from a bench rest,
12) 1/2 neck sized formed brass

One clue may be that this rifle's accuracy is not affected by heat, and my other rifles loose accuracy if I don't wait between shots.

I'd put my money on the barrel, and then on the wind. JMO, Dutch.

Good barrel, good bedding job, and precisely assembled, uniform ammunition!!

Clark: Congratulations. I love my .257 Imp. too. What a tack driver. I know you mentioned that you've never adjusted the powder charge and I am curious as to where you got your powder charge data.
As an aside, have you tried the Hornaday 75 gr. v-max? So far, I've found this to be the most accurate bullet for me when seated 0.010" off the lands (measured to the ogive) with 46.4 grs. of IMR-4895. It seems to me that IMR-4895 is just the "natural" powder for this cartridge since every time I hear about the most accurate powder, it turns out to be this one. Good luck, Bear in Fairbanks

[ 02-11-2003, 00:52: Message edited by: Bear in Fairbanks ]

Clark: I also am going through an accuracy phenomenon over the last several years! First of all I simply will not do load development in any windy conditions! Even a 5 mile per hour wind at my back muddles my results! I only send a load testing bullet downrange when my wind flag streamers are at rest! This alone has cut my load testing to find accuracy in half! A person has to be patient though to do this! I often load my truck with all my guns and gear and drive the 9 miles or so to my range only to sit and wait or not shoot at all rather than shoot in puffing winds! Another thing I have become a strong believer in is lapping my scope rings carefully for 80%+ contact with the scope - prior to the lapping I bore sight the bottom rings to the scope! I center the scopes adjustments then make sure the rings are not going to use excess amounts of or most of the scopes adjustment to bore sight. I was told by a BR type that this procedure aids in accuracy and a Rifle holding zero! I do not know for sure but it has also helped me achieve accuracy that I am happy with much quicker than prior to using these procedures. I also use 20 hand picked matched for exact weight pieces of brass for load development in each particular Rifle.
Also about 6 years ago I bought and began using the excellent and inexpensive Sinclair Over All Length gauging tool that determines exactly the correct length of a bullet to be exactly as far into or off the leades of the rifling as I want! Great tool and mine was only $16.00! The more details a shooter controls the easier it is (in my opinion) to obtain accurate loadings quicker!
I am so happy your Rifle is shooting that well at 100 meters! Good for you! By coincidence I have just this past year been gathering parts, components and dies for a heavy barreled Varmint style Rifle in caliber 257 Roberts Ackley Improved! I have a Redding 3 die set for 257 A.I., a Leupold 8.5X25X40mm scope, a Winchester pre-64 Model 70 action and a Marksman style stock already! All I need is the barrel and the smithing work. I hope to be online with that Rifle by early summer!
I will be using my 257 A.I. for Antelope Hunting as well as long range Coyote and Rock Chuck Hunting! Thanks for the above tips I will copy and save them for when I need them again!
Good luck in the fields with your new rig!
Hold into the wind
VarmintGuy

It is all about luck. I envy the accuracy of your latest rifle. Have fun!

Dutch, eldeguello,
Thanks for responding.

Bear,
I got the starting point of 49.4 gr from Quickload as 55 kpsi. I have not tried the V max, but I will.

Varmint guy,
I should also say that this was the first rifle that I epoxied the Weaver scope mounts to the rifle while the screws to the rifle were loose and the scope was on the gun. The scope rings were tight to the scope. When the epoxy cured, I knew I had scope ring alignment, and then tightened the mounts to the rifle.

Mingo,
Luck, like flipping a coin, means too many factors out of control.
I don't know what to believe. Prior to that rifle's first group, I thought it was most likely all because I was a bad shot.
I am afraid to change anything without testing that one variable.

[ 02-11-2003, 07:08: Message edited by: Clark ]

And another thing, the 100 pieces of WW brass I have been working with have such low neck thickness variation, I cannot measure any, from case to case or around the mouth of one.

You're probably doing this already, but I found that weighing the bullets also helps.