.357 Subsonic Load Issue, Input would be welcome!

[farmer7]

I recently bought an almost as new JM Marlin in .357 at a very sensible price, it shoots very well with supersonic loads using Unique with Kranks 158gr cast RNFP at 1200 fps and also Hornady XTP's with H4227 at 1650fps. However using the cast 158gr RNFP at subsonic velocities it groups like a shotgun, 25 yards 2" at best and anything between 5 and 12" groups at 50 yards! Using the same bullet at 1200fps it will put 5 into 1 1/4" at 50 and 5 into under 3/4" at 25 yards.

I'm just looking to find an accurate load anywhere between 900 and 1050fps for plinking just to keep noise down a bit. I've been using Trail Boss for the light loads.

I know there's a good few Marlin shooters here, what loads have you got shooting well at the lower velocities???

I was assuming stability issues but there seems to be a lot of gallery shooters able to have them shoot well at subsonic velocities with a range of weights from 125-180gr.

Any pointers gratefully received!

[Sim G]

I'm really not a lover of Trail Boss in small cartridges. Firstly, it wasn't designed for them. Secondly, despite being bulky it's still a fast burning powder and I've found that even though fast powders can make decent gallery loads out of a carbine, because of the longer barrel, you need the slower burning powders. That said, I've had good use with Bullseye and a 158gn SWC, using 3.3gns, fir about 900fps. But my favourite load is 6.0gns of HS6 with the same bullet. Slower burning and more of a push, than a snap in recoil. Gives around 975fps and is stonking accurate in my 16" 1894 CP.

[DavidRees]

See the following thread for my recommendation:

http://full-bore.co.uk/viewtopic.php?f=11&t=26909

Viht N340, 4.7gr, GM 158gr LRNFP or LTC.

[farmer7]

Thanks for the input folks. Do Macleods in Tain stock N340 do you know David? Sounds like it's worth a try.

[farmer7]

I'll give my local shop a try for HS6 or N340, I wont hold my breath though, last time apart from TB its only rifle powders they had.

So would you be thinking that the inaccuracy of my slower load is a powder issue rather than speed or bullet choice? I have a can of Unique and according to Quickload at 4.2gr it should give around 1045fps at less than 40% case fill. But that is under the recommended start charge for .357. Would it be unwise to try? Detonation issue???

[Sim G]

No, there's no issues with .38spl data in .357 cases.

I didn't have much luck with Unique in 38/357. Which is a shame as its my powder of choice in .44spl, 25-20, 32-20, 44-40 and rifle cartridges using lead bullets!

[Daryll]

I've always used medium/fast powders for gallery rifle loads.... normally around 3.8 - 4.0 gns of something like Red Dot, Accurate#2, and my currant load is N320.

These are all in .357 cases behind a GM hardcast 158gn boolit.

HTH

[Christel]

4.5gn Trailboss, 158gn cast bullets. Works very well in both our rifles.

[farmer7]

I'll try some Unique this morning at 4.2gr and see how it goes. It certainly shoots well at 1200fps.

As for Trail Boss, many people seem to have great luck with it in .357, including you Christel but I've been up and down between 4.0 and 5.2 and it just won't group! Whether or not it's that velocity range or the powder choice I'm not sure yet!!!

[ovenpaa]

As Christel says, 4.5 grains of TB is the accuracy node in both .357Mags here, one is a Remlin 1894C and the other is a Marlin 1894C Microgroove and whislt confirming zero I have shot several good touching groups at 25m off my elbows with both rifles and this load. They are built to factory length using 158 grain RNFP from Dodgyrog of this forum. We loaded the last of a lot of 1000 last weekend so will need to get some more in very shortly :)