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Re: IMR 4198 loads

Posted by Larry Gibson on Saturday, 2 August 2014, at 6:16 p.m., in response to IMR 4198 loads, posted by Jerry Ipsen on Saturday, 2 August 2014, at 2:37 p.m.

That load is safe for sure but as to accuracy? That load is below Lyman's recommended start load. From my own pressure tests that low a charge of IMR 4198 is somewhat position sensitive and does not ignite or burn efficiently under 31 gr with 405 or less weight bullets. Of course a lot depends on the bullet. It does need to be a cast bullet for original TDs as jacketed bullets are not recommended because of the "low steel" the barrels were made of. Also jacketed bullets will be .457 or .458 which is on the small side for TDs.

A good softer cast (20-1 or 16-1 alloys are highly recommended)bullet of 40 gr +/- is a good load. I suggest you research Spence Wolf's book on loading for the TD. I've found that SR4759 is a better smokeless powder to use w/0 a Dacron filler. However, both AA5744 and IMR or H4198 are good powders if a Dacron filler is used. An excellent load is the Lee 459-405-HB cast of 20-1 and left as cast over 25 gr of AA5744 with a 1 gr Dacron filler. Velocity will be 1300 fps +/- with 22 - 24,000 psi , well under the SAAMI MAP for TD level loads. Another excellent load is 35 gr IMR 3031 with a 3/4 gr Dacron filler. Velocity there will be around 1250 fps (assuming a rifle for both velocities) with 25,000 +/- psi.

Larry Gibson


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