This is simply a 7mm-08 Ackley Imp with a little longer neck than the standard 7mm-08. The SS stands for "Sore Shoulders ;-). The longer neck is to hold the bullets in better alignment. Also the fitted neck with the minimum tension will provide a little more holding grip. The radial neck clearance of .0006" will allow for minimum brass expansion. The brass spring back is all that is required to hold the bullet, I hope. Varmint Al has successfully used this system. The chamber was designed with that in mind.

The rifle will be chambered with two reamers, one for the body a 243 AI and for the neck and throat a 280 Rem AI. The 280 AI reamer established a chamber OAL of 2.055" providing a .305 long neck. The 243 AI reamer provided the body, with a .2762" pilot and head spaced with a 308 Win gauge minus .004".

Note: The two reamers are compatible at the shoulder the 280 AI is .455 and the 243AI is .456". The later will clean up the body completely.

The barrel twist at 1-11" will handle any bullet weight nicely up to 160 grain. The rifle will be used mainly for deer hunting. My preferred bullet weights for deer are in the spectrum of 120 to 140 gr with 7mm rifles.

I think this will make a very serviceable game rifle. The barrel was used before and had a NECO Fire Lapping treatment, which had washed out the throat on a 280 Ackley, improved. Smith barrels are cut rifling and not hand lapped by the maker. The gun-smith or the individual shooter either does hand lapping. The barrel as it is now is very accurate and did group 3/4" at 100 meters with 139gr Hornady bullets in the 280AI. Moly plated bullets and fire lapping has nearly eliminated all the copper fouling.

Cases are made from Winchester 7mm Mauser brass to obtain the .300 long necks. The process is quite simple.

With a water volume of 54.6 gr water to the neck, a loading density of 100% with Re-Loader 19 should be attainable? A load for the 7mm-08 Rem for the 139 gr Hornady is listed in the Alliant Powder manual with 52.0gr of Re-Loader 19 at 2850 ft/sec. I don't know how they got 52.0 gr into the standard case? It looks like Re-Loader 19 is too slow for this case. A modest 5% increase in powder would make the load 55.2 gr. or 101% loading density, without too much compression.

Re-Loader 15 may be better? A load for this powder in the 7mm-08Rem is 43.0gr at 2830 ft/sec. The loading density in the improved chamber for this load would be 80%. An attainable increase in velocity of 6% would mean 3000 ft/sec. A 6% powder increase would be about 46.0 grains. Which in turn relates to an 85.5% loading density. At this stage I believe that Re-Loader 15 is the logical choice of powder for the 139-140 gr bullets. Unfortunately my powder supply has no Reloader 15 so I will try the IMR 4350 first. Since the bullets will receive the Moly plating treatment, a small increase of powder will be necessary to overcome the reduction in pressure caused by the lubricity of the Moly.

Please review this page again. The barrel work should be completed very shortly, and load development should not be very difficult and straight forward. I am still waiting for the Redding dies.

This cartridge will nearly equal the performance of the standard 270 Winchester but with a short action and a lot less powder and recoil. Also the action and the trigger on this rifle are not top notch and would not be my recommendation for a custom rifle. Below load testing June 21, 1999 showed erratic velocity readings due to low battery in Chrony.

Table # 5: With 139 gr Hornady Moly plated. Fired July 16/99. Lengthened throat to 0.270. The load now has 0.040 clearence in magazine.

Note: 53 gr of Re-loader 19 is all the case will hold, and that is with about 1/8" of powder compression. The full potential of the case can not be realized with Reloader 19. Also accuracy is good with some loads. IMR- 4350 is just a little faster and seems a better choice. All above loads are still below bench mark pressure and show no signs of high pressure. Case holds 51.5 gr. of IMR 4350 to neck. This powder may reach 3000 ft/sec with moderate pressure? Loading density with 51.0 gr IMR 4350 would be 93.4%. The rather large groups are the result of the poor rear bag during chronographing making adjustments for each shot. Most groups were two bullets close together with the third one going astray. Also I am not happy with the run out the dies are producing more tuning is required.

Table # 6: With 139 gr Hornady Moly plated. 140 gr Nosler Silver Tip. 130 gr Barnes-x BT. Fired July 27/99. Lengthened throat to 0.270. The load now has 0.040 clearence in magazine.

 Note: The Barnes-x bullets loosened primers. They never performed in the cut rifling. Either of the two Hornady and the Nosler Silver tips are good hunting bullets. The head expansion of 0.4693 is about right for the cases. Like most domestic cases the bases are much too small and will eventual loosen the primer pockets. Better dimensional brass would benefit case life.

Table # 7: With 139 gr Hornady and 120 gr Nosler BallisticTip, all Moly plated. Bullets 0.010 off lands. All groups 3 shots.

Note: Both loads shoot to the same point of aim. The barrel for test # 7 was free floated while others had forearm tip pressure. The bolt clearence was reduced from 0.006" to 0.0015" with two bands of 0.002 steel shim stock and epoxyed in place behind the lugs and in front of the bolt handle. All loads were straightened to 0.0005" bullet runout, because the bullet seating die produces up to 0.005" runout. The rifle is now ready to go deer hunting.

The results of some of the poor groups previously reported were caused by a faulty scope. The scope was send to the Leupold repair depot. It came back just a day before my hunting trip. I managed to reinstall and sight in the scope with my Harris -Bipod the next morning and went hunting. Just in case I took along another rifle. The 120.gr bullets had to be set into the case another.030 so they would fit the magazine. Also with the accuracy of the rifle, load and open country shooting there is no real need to use the magazine. I keep the ammo warm in my pocket and only load the rifle when I see some thing to shoot at. I had the throat lengthened 0.070" to suit the 139 gr Hornady bullets. So a compromise of .225 would have been better.

I bagged two Whitetail Deer and one Mule Deer with three shots. The first two a doe and a buck at 200 m. I had a chance to measure the distance with the jeep odometer. The doe was hit in the upper neck under the ear. The buck with a frontal shot under the chin. Both instant kills. The Mule Deer doe at 275 to 300 m was a broadside shot in the lower neck about 1/3 down. The aim was at the top of the neck; the bullet dropped about 4", another instant kill. Since I did not chronograph this load I think it has a 260 m zero. All the deer were taken sitting with a Harris Bi-pod and sling, providing a rock solid shooting support.

Since the deer were in the 175-200 lbs. range, the Moly coated Nosler120.gr Ballistic tip is totally adequate for open country deer hunting. The bullets did not exit but completely demolished the vertebra in all cases, so penetration is good to 300 meters with careful placement of the shot. I am very impressed with the performance of the bullet and the 7mmSSAI cartridge, and of course the modest recoil suitable for juniors and women and oldies like me.

I tried the140, 130 and 120gr Barnes-x but the accuracy and the copper fouling was terrible. This rifle does not like the Barnes-x's. As I said before this rifle is near 270 Winchester performance. And 270 Winchester performance needs no introduction. Now we need to build a rifle with top of the line components?

Is it worth while to accurize the Wby Vanguard action? My gun smith thought it was. Since I build another rifle in the same caliber. He rechambered the rifle to a 284 Win and Blue printed the action and lenghtened the magazine to take full advantage of case capacity. This is a fine caliber but a bit more power, and uses a standard cartridge.

Warning: Loads used were carefully worked up in one particular rifle and may not be safe in other rifles. Moly plated bullets were used in all loads, the use of non plated bullets could dramatically increase pressures to unsafe limits.

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