Accurate 43-250J

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  • Last Post 06 September 2016
Eutectic posted this 21 June 2016

I have been wanting for some time to try a custom fit bullet in the 44. This has been held up for two reasons. First was the cost of having a cherry made, and second, Lyman 429421 has given excellent accuracy for over 50 years and several pistols. Still the thought that better accuracy might be possible continued to weigh on my mind every time I shot a 44. The front band on 429421 is short in order to fit all guns, at least it is full diameter which many other copies are not. I wanted to see if a close fit front band would give better accuracy.

50% of my excuse evaporated with the development of Computer Numerical Control (CNC) machining. Accurate lists 43-250J a copy of 429421and Tom can make any changes requested. I decided to order a dual cavity mold with one cavity 43-250J and the other modified with a maximum front band to contact the throat in my 629 DX. This will be a good test same mold same alloy cast at the same time. I even lubricated them alternately to keep everything identical.

Tom makes a top quality mold, as a project in my materials engineering class it would get an A+. The real test of any mold in in the casting and it did not disappoint. Those beautiful bullets fell right out, no burrs to deal with, no polishing needed. Size and roundness is perfect to 0.0005, the part line is almost invisible. 43-250J is so close to 429421, bullets from my Lyman mold will almost fit in the cavity. The mold needed to be run hot to make good bullets of the 2/6 alloy, cast size is 0.431 - perfect. I ran off several hundred, sized them 0.430 lubricated with my beeswax jojoba oil lube

The morning sun found me 40 miles from home with a car packed with gear, a lunch bucket and the 629 DX with a 4 power Leupold. I warmed up the gun on rocks on the berm. The rocks absorbed a box of ammo, and I started on another box. Plinking with a 44 is fun, but it was time to get to work.

First served were 1000 fps loads 8.0 gr. VV320 and Winchester primers. I set the targets at 25 yards because of the gusting shifting wind. One of the first 12 round groups was just over an inch! I alternated bullets. The results were promising, average of 4 groups each was 1.67” and 1.22”. Bullets with the longer front band were best. Unfortunately, the standard deviation overlaps so the result is not significant. More shooting needed, but the 1000 fps ammo had run out.

I thought a hot load might show the better sealing of the fitted slug. 15 gr. VV105 provided the power for 1250 fps. This is not a full magnum load, but that requires a work-up. I was not about to use my 429421 data with a bullet which seats to throat contact. My fears were groundless, there was no velocity difference between the bullets. 

I only fired 2 groups each, my precision was going, and I was throwing called fliers. Shooting a 44 off the bench attempting to make each shot as perfect as possible is a far cry from a plinking session. Over 200 rounds of 44 had degraded the shooter.
There was an accuracy difference 1.09”vs 1.19”. Again the difference is not significant. The Lyman 429421 has averaged ~1.6” over many range sessions in this revolver. It is the bullet in my standard load to see if I am shooting well. I will have to test the bullets side by side, but it looks like the Accurate bullets are well - more accurate.

Lyman 429421 is an excellent well-balanced bullet design. Slow-fast, near-far it does it all well. Accurate makes it even better, offering cast diameter to match your alloy in a top quality mold. You can order the front band extended to match your chamber. This MAY give better accuracy but it can also make the bullet gun specific.

I had hoped for a big accuracy improvement. Dreams of consistent sub 1” groups did not materialize. It is going to take more shooting and perhaps load development to prove if there is an accuracy advantage to a lengthened front band. This revolver will shoot consistent 1” groups at 25 yards with 240 grain jacketed bullets, so I am close to the accuracy limit.

Testing at 50 and 100 yards is coming to see if group size is linear. If you extend the front band as far as the meplat you get a wadcutter and we know what that does to long range stability.  Has the shortened nose affected stability? We will see.
Steve

Lyman 429421/ LBT blue lube, 43-250J, 43-250J extended band

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Ed Harris posted this 21 June 2016

Very much looking forward to your 100 yard results.

The extended front band might be just the ticket to reach the lands in a Micro-Grooved Marlin 1894S in .44 Mag!

What does the modified bullet weigh?

The .431 diameter sounds good. Sure would like to see what it does with 11 grains of Herco or 7.2 grains of Bullseye...

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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mtngun posted this 22 June 2016

Thanks for the data, Eutectic.

Yes, long bench sessions with a 44 mag are hard on the shooter.  :D

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Eutectic posted this 22 June 2016

Short band bullets in 2/6 alloy are 251.5 and the long band is 256.1. I could have tried to compensate in another band, but this causes another variable. VV320 is almost the same speed as current Bullseye. 11 grains of Herco would be a nice moderate load.   Steve

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Eutectic posted this 06 September 2016

I managed a day at the range, and it was fun?? Hurricane Hermine was providing 40 MPH winds and blowing down the target holders. The wind was shifting and we even had dust devils on the range. I just forgot about any attempted wind correction. There had to be a hurricane on my day off! At least there were few shooters on the range. Both the bullets were stable at 100 yards. I would have liked to do 200 yards but that was not available. Groups were linear 25, 50 and 100 so I have not ruined the aerodynamics by extending the front band. This was with 15 grains VV105, bullets, lubed with 20% jojoba oil/beeswax.   It looks like accuracy improvement is 5-7% for the fitted front band. This is not much and I am not sure of the exact number, I had to disregard the lateral dispersion. Both Lyman 429421 and Accurate 43-250J are very good, so improvement is slight. Still, it is worth it to get the best bullet for your revolver if you are ordering a mold.  

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