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March 30, 2005

The 257 Roberts H&R Ultra Rifle Conversion.


This rifle started out as an H&R Ultra 223Rem Varmint rifle with a 24" bull barrel and a laminated stock as supplied by H&R. The stock had enough wood on it for me to reshape it as seen above. The 24" octagon barrel was also made from the exiting barrel. The rifle was rebored and chambered by Ron Smith of Wimborn Alberta.

Ron says the H&R barrel steel (Green Mountain Barrels) is as good as he can buy for his custom cut rifled barrels. This barrel has a very smooth finish and is not hand lapped. Ron says his barrels do not need hand lapping? I think they would even be better if they were hand lapped.

Stock before and after

I did a minimal NECO fire-lapping job with 10 rounds of 800 grit and 10 rounds of 1200 grit. This saves a lot of break in ammo. As can be seen below the rifle started to shoot well after only 50 rounds. I do this procedure with all new hunting rifle barrels. These fine grits in small lots do not harm the throat.I also refitted the latch and installed a heavier latch spring for a more positive lock up at the same time lightening the trigger to 16oz. The scope bases are Weaver style with B-Square lightweight rings. The front base is hand fitted to the octagon barrel

The pictures shows the new barrel stud, screwed and J-B welded to barrel.

The stock is shown before and after reshaping. Drilling a deep 7/8 hole into the butt reduced the weight of the stock further. Nearly a pound of weight was lost in total including the weight of the recoil pad. Laminated stocks are very heavy and serve well for reducing recoil.

This rifle toke me several month to build. Fortunately I had the use of a friend's machine shop where I did the milling of the octagon barrel and made the barrel stud and a new crown. My friend Eddy Mech did the checkering and the barrel bluing. Since I had no ideas about octagon barrels I developed a MS EXCEL program where you can calculate the weight and the dimension across and the width of the flats.

Stock Details

The barrel has a 1-10 twist and shoots 100gr bullet at 3150 and 75g V-max at 3450 with very good accuracy. The 100gr bullet will group 3/4" with three shots and the 75gr ". This is as good as a bolt-action rifle. Also hand loading for this rifle is very finicky due to the lock up stretch, 51500 psi is about max in my opinion. The Roberts case is large enough to use slower powder to reach that pressure. Careful load development is required lest you get sticky cases that the ejector will not eject.

 As on my previous 25-06 Ultra I installed a notch to remove stuck cases. A smooth polished chamber will help with ejector problems. I used the original ejector of the 223 and reshaped it with a Dremel grinder. All sliding surfaces on the ejector were polished plus the bottom of the barrel inside the ejector housing. I do like the ejector better than an extractor. Also the new type of extractor is positive, but in cold climes where you need to wear gloves empty cases are hard to get a hold of, since the only come out 3/8" or so. With the ejector you can hold your hand where you can catch the empty case. A stronger ejector spring is another remedy for stuck cases.

 This is an economy single shot rifle that has a beautiful balance and is more than adequate to take deer and varmints. At 7lbs -4oz, complete with a 3-9 Sightron scope, it is a delight to carry and has negligible recoil. It is unfortunate that this caliber is not available in a factory Handi rifle; rather they produce a 25-06, which in my opinion is too powerful for this frame. As you notice the rifle has no recoil pad in the classic tradition, besides non-is needed for the 257 Roberts?

The gap created by the octagon barrel on the original forearm was overlaid with wood.

The idea of the 257 Roberts came from the use of my 25Hunter game rifle the ballistics of this rifle is the same as the Roberts except the 25 Hunter operates at a higher pressure with a lesser case volume. The 25 Hunter has proven to be a "Ne plus ultra" deer rifle. The above single shot Roberts is in the same class. Unless you can do most of the customizing yourself, I don't think the above would be an economical venture, even though it's outcome is very appealing.

The action is bedded with Devcon Steel to remove side play.

This keeps the barrel from torqueing and greatly improves accuracy. The hinge piece after careful fitting is bedded with Brownell Steel Bed and the rest of the forearm is bedded with Dow spray foam. This bedding method seems to work well on three other rifles. The barrel stud recess gets a thin rubber washer, not shown. To get slightly more latch engagement, a small amount of metal was removed on the forward face of the latch where it makes contact with the investment casting of the frame. All the rough edges of the latch recess were filed smooth. To allow full forward movement of the latch the thumb leaver stop edge needs some metal removed. In factory configuration I found the barrel latch only engaging 50%. A latch leaver that has excessive up and down wiggle is an indication of how much latch engagement you have. You want solid 100% latch engagement. 

Some loading thoughts.

 Since I had such great success with the 100gr Barnes TSX in my #1 Ruger cal. 26-06 I thought I give them a try in the 257 Roberts. Stability calculation indicated that the 100gr TSX bullets needed 3200 ft/sec for a minimum stabilization factor or125%. Also I wanted to stay below that velocity if possible.

H4350 46gr 3065 ft/sec produced a group 5/16" with all three bullets touching, very nice. Next load one more grain of H4350 produced 3215 ft/sec av. and the group opened up to 1.0". 48gr H4350 produced 3266, that is only 50 ft for one grain of powder and indicates too much pressure.

 IMR4350 did very well too with 47.0gr with a 1" group 2 bullets touching and one out level to the left. I called that shot, so the group should be less than one inch.

 I only tried three shots with H4831 and 52.5gr 3229 ft/sec this is a compressed load at 104% load density, usually a load like that works well, but in this case it produced the largest group of 2". The pressure curve of this powder is much different from the other two powders. I think 51.5gr will do a better job with this powder? I found out that 3150 ft/sec with a 100gr TSX bullet is just about perfect for this rifle.

 All three powders produced higher velocities than indicated by Quick-Load, and of course higher pressures, with H4831 as much as 100ft/sec and 4kpsi. This is quite a normal variation in powder burning rates. That is why loads need to be started 10% lower than indicated in loading books. The anomaly in case volumes is another reason to start with a lesser load. Every powder batch has a batch.# number and they all have a different burning rates the variations are within set limits.

  Danger: Above loads are not suitable in any other rifle and should not be used.

 I like to point out that this Handi rifle is like many others very finicky about pressure if you want good accuracy.

A one-grain difference in powder charge can make a huge difference in the accuracy. I can recommend only the slowest powder that will provide a reasonable velocity and accuracy.

Keep down the pressure your Handi will love it. Recently the rifle developed a 0.003" gap and accuracy went sour. See my gap fix. Accuracy is back with five consecutive three shot groups at 3140 ft averaging 0.480"

 Note: All loads were developed and worked up with Moly plated bullets, Quick-Load and CHronograph.

  Fred the Reloader and Wildcatter