need help with 357 rifle loads

[Flintrocker]

Using CCI Blazer Brass, 158 grain JHP factory loads, my .357 magnum rifle grouped 3 shots in 1 7/8 inches, 5 shots in 2 3/4 inches. All at 100 yards, rested on sandbag.


I am trying to duplicate that factory load accuracy using Speer JFP bullets over 15 grains of H110, CCI 500 primers, in PMC brass, but groups are closer to 6 inches than 2 inches. I also tried 14 grains of H110. Also tried 8 grains of HS6. All with a moderate roll crimp using a separate Lee crimp die.


My question is what to vary next. I am limited to these two powders, due to local supply problems.


Is a hollow point bullet likely to be better? I could get some Hornady 158 grain XTP HPs easily here. Or should I switch to the Blazer brass, rather than PMC? Or just keep varying powder charges? What do do first, second, and third?


Any advice on how to match the factory ammo accuracy would be much appreciated. Thanks in advance.

 

[rcmodel]

All your loads are pretty light for the powders you are using.

Hodgdon says
Max with H110 is 16.7.
Max with HS-6 is 9.5.

Increase your loads a little more to get a clean burn and complete bullet bump-up to fit the rifling.

rc

 

[ReloaderFred]

Welcome to the forum.

I would first try a firmer crimp, since H-110/Win. 296 (same powder) seems to ignite better with some resistance. The longer the bullet is held in place, the better the ignition.

I've found Hornady XTP bullets to be very accurate in my testing, so if you can purchase some of those, they would be worth a try.

As for the brass, PMC brass is somewhat thicker than some of the domestic brass. You might also try the Blazer brass, since it couldn't hurt.

For the most part, I've gotten better accuracy out of my .357 lever action rifles using heavier bullets. I cast a 185 gr. gas checked bullet that produces great accuracy, but I'm using Hodgdon's Lil'Gun powder for it and getting 1,710 fps velocity across my Pact chronograph.

Since you're limited on the powder choices, about the only things you can change are the crimp, brass, bullets and primers. Any, or all of them can have an impact on accuracy.

Hope this helps.

Fred

 

[gamestalker]

Really you've got several probable causes for the poor accuracy here. I load nearly exclusively with H110/296 and have always achieved very accurate loads.

H110 performs at it's best when it's worked up toward the maximum. Simply put, it needs full pressures to produce a good consistent pressure curve.

And second is the primer. H110 requires a magnum primer to consistently ignite it.

And last, a firm roll crimp is also necessary to contain the pressures as long as possible to a produce a consistent burn.

And HP's do typically produce better accuracy than SP's do. XTP's are a very good projectile for full house H110/296 loads.

So to recap, use magnum primers, JHP's, firm roll crimp, and work those charges up to maximum. Brass isn't really much of a factor in my experience, I use mixed brass all trimmed to same lengths with great results.

GS

 

[ArchAngelCD]

Like already said above, up your charge weights to near the max and I recommend magnum primers for both H110/W296 and HS-6. Both will burn better and more consistent with a magnum primer.

When firing a 158gr jacketed bullet in a Marlin Carbine I can generate an AV of 1826 fps using H110/W296 and a CCI-550 primer. Accuracy is 1.25" @100 yards.

Welcome to the forum...

 

[Macchina]

ArchAngleCD: Could you possible share that H110 load with me? I have crept above Max and am still getting about 100 FPS before what you are... This is from an 18.5" 77/357 at about 20 Degrees F. I think this is probably due to the temperature.

 

[murf]

get the xtp bullets and switch to cci 550 primers. good luck, and welcome to the high road.

murf

 

[ch84]

Have had good luck with the 140 or 158 xtp with max or near max charge of 296 with a heavy crimp an cci 550s

 

[stubbicatt]

This my be futile advice, but with cast bullets and 2400 I was able to get really good accuracy, minute of soda can at 100 yards with a Marlin several years ago.

I say futile as I have no idea whether 2400 is even available.