38-55 Goex FFg 255gr and 337gr recipes

[JackSlade]

What's the consensus on compression with Goex FFg?  I've heard anywhere from .25" to .38". I have .030 fiber wads, and a custom mold for 255gr and 337gr big lube bullets. 1:20 tin/lead alloy.rifle is cimarron high wall, 30" barrel 1:18" twist.

 

I can ring steel pretty good at 300 but couldn't find out where my POI was at 100yds. I'm at the point now where I'm ready to do a new batch of rounds and am curious if I should standardize any of the loading process before adjusting charge weight.

 

Spg pan lubing and brass is starline 2.08" federal LRP 210.

[Sedalia Dave]

Don't change your load.  With the sights set for 300 yards, the round is hitting 24" to 36" high at 100 yards. 

[JackSlade]

Yeah I figured I was lobbing artillery when I was holding at the bottom of the target frame and still wasn't hitting the 100yd cardboard.

 

I really need a chrono, I would like to get up to 1300 fps

[Uriah, SASS # 53822]

JackSlade,

I concur with SD. 25” high at 100 yards via Hornady ballistic calculator. 365 gr bullet, 38-50 Rem-Hepburn, 1295 fps.

I’m running .22” to .25” Goex FFg and Olde Epnsford (sp - I have the bottle in front of me and I can’t figure out what the first two letters are).

 

How about the twist on your rifle? Seems kind of slow. 
 

Uriah

[JackSlade]

Cimarron states their twist is 1:18. Not sure why that's considered their standard over something like 15

[Hoss]

On 9/30/2024 at 3:45 PM, JackSlade said:

What's the consensus on compression with Goex FFg?  I've heard anywhere from .25" to .38". I have .030 fiber wads, and a custom mold for 255gr and 337gr big lube bullets. 1:20 tin/lead alloy.rifle is cimarron high wall, 30" barrel 1:18" twist.

 

I can ring steel pretty good at 300 but couldn't find out where my POI was at 100yds. I'm at the point now where I'm ready to do a new batch of rounds and am curious if I should standardize any of the loading process before adjusting charge weight.

 

Spg pan lubing and brass is starline 2.08" federal LRP 210.

I could not get anything heavier than 310 to stabilize in my Uberti HiWall 38-55. But not a super accurate load. The 260grn was most accurate, but would not reliably knock the targets off rail past 300 meters. If all you have to do is hit them the 260 is great. 

[JackSlade]

 

16 minutes ago, Hoss said:

I could not get anything heavier than 310 to stabilize in my Uberti HiWall 38-55. But not a super accurate load.

Were you noticing keyholing with the heavier bullets? Or just the group opening way up?

[Hoss]

2 minutes ago, JackSlade said:

 

Were you noticing keyholing with the heavier bullets? Or just the group opening way up?

With the 334s I could hear them buzzing. couldn’t hit a Buffalo if one swallered me whole!
The 310s stabilized but big groups.  

[JackSlade]

That's concerning. Lol I sprang the extra money for a custom mold. I guess I'll see what happens after I cast and load some

[Equanimous Phil]

On 9/30/2024 at 10:45 PM, JackSlade said:

[...] custom mold for [...] 337gr big lube bullets. 1:20 tin/lead alloy.rifle is cimarron high wall, 30" barrel 1:18" twist.

 

On 10/2/2024 at 5:33 AM, JackSlade said:

Cimarron states their twist is 1:18. Not sure why that's considered their standard over something like 15

 

14 hours ago, Hoss said:

With the 334s I could hear them buzzing. couldn’t hit a Buffalo if one swallered me whole!
The 310s stabilized but big groups.  

 

I own a Shiloh Sharps in 38-55 with a 1:16" twist. Back when I ordered a custom mold from Accurate I considerd a 331 grain bullet the heaviest I wanted to try. Unfortunately, I shot that rifle only a couple of times, yet, so not much info on accuracy etc. with that bullet.

 

Edit: Found my old thread. And here's another one on 38-55.

 

[Sedalia Dave]

Here is a bullet stability calculator you can use to get a general idea of how your bullet will perform.  Playing with the numbers BC doesn't have much impact.  What does is the weight, diameter, and length of the bullet. Obviously MV and twist rate have an impact. 

 

https://bergerbullets.com/twist-rate-calculator/

[JackSlade]

8 minutes ago, Sedalia Dave said:

Here is a bullet stability calculator you can use to get a general idea of how your bullet will perform.  Playing with the numbers BC doesn't have much impact.  What does is the weight, diameter, and length of the bullet. Obviously MV and twist rate have an impact. 

 

https://bergerbullets.com/twist-rate-calculator/

I used another that said it should be stable. 1200fps is pretty attainable with Goex FFg, right?

[Sedalia Dave]

41 minutes ago, JackSlade said:

I used another that said it should be stable. 1200fps is pretty attainable with Goex FFg, right?

Not sure. I haven’t played enough with BP and my chronograph. 
 

 I do know that for non-pointy bullets, you don’t want the MV to be too much above the sound barrier. 
 

All Bullets tend to be unstable in the transonic region. For the high speed low drag long range folks. The maximum range for a given load is the point at which the bullet slows down below the speed of sound.