This article written by Jim Searcy, appeared in Fouling Shot #207, Sept/Oct 2010.
A few months ago, on a cold winter Saturday morning, I was sitting at the kitchen table planning my day. It was too cold to go to the gun club so I opted for a gun show instead.
Three hours later I was on my way back home with a new project rifle. The rifle in question is a model 146 Husqvarna. For the uninitiated this is a 9.3x57 Mauser built on a model 98 action. It is a graceful rifle cham-bered for a cartridge which just begs to be fed cast bul-lets.
After some research I learned the following: Hornady dies are available from Midway; Norma brass is also available from Midway; Jacketed bullets, if not plentiful, are available from several manufacturers; Cast bullets and molds are not common but they are available.
A quick review of available loading manuals revealed only one reference to a cast bullet load. This is men-tioned in Wolfs Big Bore Rifles and Cartridges, and con-sists of the Lyman 366408 bullet over 15 grains of Unique.
I wanted two cast bullet loads for this rifle. One was to be a light load for recreational shooting. The other would be a hunting load at higher velocity. While the tar-get load would be based on a plain base bullet, the hunt-ing loaded needed a gas check design.
The Target Load:
Mike Rygwalski of Northern Star Cast Bullets kindly supplied me with a box of 250 grain plain base (PB) bul-lets made with a borrowed Rapine mold. I do not have a number for this mold. These would not be a permanent solution for bullets but they allowed me to start the pro-ject while I searched for a mold of my own. Ultimately I did find a Lyman 366408 on EBay. Lets not discuss what that mould cost me.
Some time on the internet helped me confirm that 358 Winchester data, judiciously applied, would provide a starting point for my load development. The 358 case is slightly smaller than the 9.3x57 case but beware of using this data as is since the 358 is loaded to much higher pressures than is the 9.3x57. I have found 375 Winchester data to provide a useful check point as well. Be very careful. Start way low and work up slowly.
A word or two about cases is in order before we get to the load development. Very usable cases can be made by running 8mm Mauser cases through the Hornady dies. The bolt closes slightly tight for the first firing and then all is smooth thereafter. This is an inexpensive alternative to the new Norma brass I mentioned above. I also found that a 357 neck expanding die is serviceable for flaring the 9.3 case mouths. A very light bump is sufficient.
A few months ago, on a cold winter Saturday morning, I was sitting at the kitchen table planning my day. It was too cold to go to the gun club so I opted for a gun show instead.
Three hours later I was on my way back home with a new project rifle. The rifle in question is a model 146 Husqvarna. For the uninitiated this is a 9.3x57 Mauser built on a model 98 action. It is a graceful rifle cham-bered for a cartridge which just begs to be fed cast bul-lets.
After some research I learned the following: Hornady dies are available from Midway; Norma brass is also available from Midway; Jacketed bullets, if not plentiful, are available from several manufacturers; Cast bullets and molds are not common but they are available.
A quick review of available loading manuals revealed only one reference to a cast bullet load. This is men-tioned in Wolfs Big Bore Rifles and Cartridges, and con-sists of the Lyman 366408 bullet over 15 grains of Unique.
I wanted two cast bullet loads for this rifle. One was to be a light load for recreational shooting. The other would be a hunting load at higher velocity. While the tar-get load would be based on a plain base bullet, the hunt-ing loaded needed a gas check design.
The Target Load:
Mike Rygwalski of Northern Star Cast Bullets kindly supplied me with a box of 250 grain plain base (PB) bul-lets made with a borrowed Rapine mold. I do not have a number for this mold. These would not be a permanent solution for bullets but they allowed me to start the pro-ject while I searched for a mold of my own. Ultimately I did find a Lyman 366408 on EBay. Lets not discuss what that mould cost me.
Some time on the internet helped me confirm that 358 Winchester data, judiciously applied, would provide a starting point for my load development. The 358 case is slightly smaller than the 9.3x57 case but beware of using this data as is since the 358 is loaded to much higher pressures than is the 9.3x57. I have found 375 Winchester data to provide a useful check point as well. Be very careful. Start way low and work up slowly.
A word or two about cases is in order before we get to the load development. Very usable cases can be made by running 8mm Mauser cases through the Hornady dies. The bolt closes slightly tight for the first firing and then all is smooth thereafter. This is an inexpensive alternative to the new Norma brass I mentioned above. I also found that a 357 neck expanding die is serviceable for flaring the 9.3 case mouths. A very light bump is sufficient.
My load development started with the Rapine bullet and two powders, Unique and IMR 4759. Cautious progression in one grain increments showed the following two loads to be safe and in the right velocity range: 14gr. Unique for 1489 f.p.s. and 19gr. 4759 for 1410 f.p.s.
These loads were developed using rifle primers. When I substituted pistol primers unacceptable cratering of the primers ensued with the Unique loads.
These loads were developed using rifle primers. When I substituted pistol primers unacceptable cratering of the primers ensued with the Unique loads.
Some of the items used in load development.
With a starting point established I selected 5 comparable loads from 358 Winchester data and loaded 5 rounds of each. The day I tested these loads it was below 25 degrees, which may have marginally affected the velocities I obtained. The loads and results are shown to the left:
Green Dot appeared pointless and I decided to save my supply of 4759 for calibers that clearly preferred it. Friends with more PB expertise than me advised me to keep velocities below 1400 fps. With the addition of one slower burning powder which has worked for me in pre-vious projects Rx7, I proceeded.
By now I had my Lyman 366408 mold in hand. I cast a supply of bullets using a 2/1 ww/lino alloy. I also mixed up a fresh batch of Darr lube. A week later I was back at the range testing these three loads to the right:
Subsequent testing has confirmed that my rifle likes IMR 4198 and the Lyman bullet. It is an accurate and mild load. Actually it performs better than any load I had hoped to find.
The Hunting Load:
The ultimate goal for this rifle has always been to be a cast bullet deer rifle. The tract of land I hunt is a mix of timber and lowland with a few small fields thrown in. Most of my shooting needs will be met with a rifle/cartridge combination that is adequate out to 125 yards. A 275 grain bullet at 1800 fps would duplicate the stout 38-55 loads listed in Wolfs Big Bore Rifles and Cartridges. I felt this should be adequate for my needs.
I wanted a gas check bullet when trying to reach this velocity. Initially I did not expect to be able to obtain a gas check .366 inch mold. While it subsequently turned out that I was quite wrong, I reasoned that the next best thing would be swaging a readily available .375 bullet down to the proper diameter. Lee Precision is willing to provide their push through lube/sizing die in custom dimensions and at a price that is most reasonable. I ordered a .368 die which arrived just short of 4 weeks later.
Sizing a .375 bullet down to .368 is not ideal as we all know but I was committed to the plan. I had three dif-ferent .376 bullets on hand. One was a 315 grain single diameter spire point which sized down beautifully but was much heavier and longer than necessary for the task at hand.
The other two were bore ride designs. The heavier, blunter 300 grain bullet simply could not be swaged down satisfactorily. The second is a 260 grain bullet which roughly resembles an oversized Lyman 31141 or a Lyman 375296 with one fewer lube groove. I am sorry that I dont know the mold number but I purchased this box of bullets a number of years ago. The exact bullet is not important here other than to say the smaller the bullets diameter, the better. My specimens started at an actual .375 and they sized down to .368 quite well. I found that adding some lube to the top band helped.
Once I had secured a supply of gas check bullets I started carefully testing loads. Initially my primary interest
The Hunting Load:
The ultimate goal for this rifle has always been to be a cast bullet deer rifle. The tract of land I hunt is a mix of timber and lowland with a few small fields thrown in. Most of my shooting needs will be met with a rifle/cartridge combination that is adequate out to 125 yards. A 275 grain bullet at 1800 fps would duplicate the stout 38-55 loads listed in Wolfs Big Bore Rifles and Cartridges. I felt this should be adequate for my needs.
I wanted a gas check bullet when trying to reach this velocity. Initially I did not expect to be able to obtain a gas check .366 inch mold. While it subsequently turned out that I was quite wrong, I reasoned that the next best thing would be swaging a readily available .375 bullet down to the proper diameter. Lee Precision is willing to provide their push through lube/sizing die in custom dimensions and at a price that is most reasonable. I ordered a .368 die which arrived just short of 4 weeks later.
Sizing a .375 bullet down to .368 is not ideal as we all know but I was committed to the plan. I had three dif-ferent .376 bullets on hand. One was a 315 grain single diameter spire point which sized down beautifully but was much heavier and longer than necessary for the task at hand.
The other two were bore ride designs. The heavier, blunter 300 grain bullet simply could not be swaged down satisfactorily. The second is a 260 grain bullet which roughly resembles an oversized Lyman 31141 or a Lyman 375296 with one fewer lube groove. I am sorry that I dont know the mold number but I purchased this box of bullets a number of years ago. The exact bullet is not important here other than to say the smaller the bullets diameter, the better. My specimens started at an actual .375 and they sized down to .368 quite well. I found that adding some lube to the top band helped.
Once I had secured a supply of gas check bullets I started carefully testing loads. Initially my primary interest
The other two were bore ride designs. The heavier, blunter 300 grain bullet simply could not be swaged down satisfactorily. The second is a 260 grain bullet which roughly resembles an oversized Lyman 31141 or a Lyman 375296 with one fewer lube groove. I am sorry that I dont know the mold number but I purchased this box of bullets a number of years ago. The exact bullet is not important here other than to say the smaller the bullets diameter, the better. My specimens started at an actual .375 and they sized down to .368 quite well. I found that adding some lube to the top band helped.
(l-r) 30-30; 308; 30-06; 9.3x57 with Lyman 366408; 9.3x57 with NEI #174; 45-70
Once I had secured a supply of gas check bullets I started carefully testing loads. Initially my primary interest was keeping all of my body parts attached in their proper positions. My starting loads produced velocities in the 1250 f.p.s. range. Eventually I did work up four hunting level loads that are safe in my rifle. They were:
During this phase of my testing, I bought an NEI 25 caliber mold on EBay. The mold was new in the box. When it arrived there was an NEI mold list also in the box. NEI shows two .366 gas check molds among their offerings. I called NEI and an incredible four days later I received a brand new .366 mold in the mail. If there is better customer service than this, I have never encoun-tered it. Thanks to the kind folks at NEI.
The mold (#174) was listed at 260 grains. Using the same 2 to 1 ww/lino alloy, my bullets weigh exactly 280 grains including gas check. By the way I am using 35 caliber gas checks (as NEI specified) and seating them with my Lee custom die. I lubed these bullets with Darr lube the same as I had done with the Lyman 366408 PB.
Even though IMR 4198 shot extremely well in my rifle with the PB bullet, I was uncomfortable pushing the charges much farther than 30 grains. I felt that moving up to a heavier 280 grain bullet indicated that the prudent course was to opt for the slower burning powders. Hence I left IMR 4198 out of the final testing.
The weather on the day I tested the remaining three loads for accuracy was far from ideal. It was quite cold and the wind was moderate to strong. I dont know if this impacted accuracy much but I did get some unexplained fliers, particularly with Varget. All three loads grouped under four inches at 100 yards, including fliers. IMR 4895 produced the most felt recoil and the loosest group. The Varget load put four of six shots into 1-1/2 inches. The remaining two were fliers, one high and one low. If I wanted a hotter load for this rifle, I would work more with Varget. It may be the right powder in some rifles.
The Rx7 load gave the least felt recoil and a nice round 2-1/2 inch group for seven shots. Actually this rifle may not be capable of much better accuracy than this. I am not sure that I am. Recoil becomes quite noticeable at 1750 fps. In any event, I am satisfied that 33 grains of Rx7 is a serviceable hunting load in my rifle. I will probably test a softer alloy next fall as I am not sure that this fairly hard (2/1) alloy will expand.
These are my experiences to date. Now that I have two good molds on hand, I am sure that more rifles of this bore diameter are in my future. If any of the readers have information to share, or observations, I would enjoy hearing from you.
The mold (#174) was listed at 260 grains. Using the same 2 to 1 ww/lino alloy, my bullets weigh exactly 280 grains including gas check. By the way I am using 35 caliber gas checks (as NEI specified) and seating them with my Lee custom die. I lubed these bullets with Darr lube the same as I had done with the Lyman 366408 PB.
Even though IMR 4198 shot extremely well in my rifle with the PB bullet, I was uncomfortable pushing the charges much farther than 30 grains. I felt that moving up to a heavier 280 grain bullet indicated that the prudent course was to opt for the slower burning powders. Hence I left IMR 4198 out of the final testing.
The weather on the day I tested the remaining three loads for accuracy was far from ideal. It was quite cold and the wind was moderate to strong. I dont know if this impacted accuracy much but I did get some unexplained fliers, particularly with Varget. All three loads grouped under four inches at 100 yards, including fliers. IMR 4895 produced the most felt recoil and the loosest group. The Varget load put four of six shots into 1-1/2 inches. The remaining two were fliers, one high and one low. If I wanted a hotter load for this rifle, I would work more with Varget. It may be the right powder in some rifles.
The Rx7 load gave the least felt recoil and a nice round 2-1/2 inch group for seven shots. Actually this rifle may not be capable of much better accuracy than this. I am not sure that I am. Recoil becomes quite noticeable at 1750 fps. In any event, I am satisfied that 33 grains of Rx7 is a serviceable hunting load in my rifle. I will probably test a softer alloy next fall as I am not sure that this fairly hard (2/1) alloy will expand.
These are my experiences to date. Now that I have two good molds on hand, I am sure that more rifles of this bore diameter are in my future. If any of the readers have information to share, or observations, I would enjoy hearing from you.
