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gunlaker
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max safe charge 38-55 IMR-4227
Jan 17th, 2025 at 4:43pm
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I'm shooting the Hoch 376310  ( ~310gr ) bullet, breech seated, in a modern highwall.   I've used up to 18gr of IMR-4227 and I think it wants more powder.

How high can I go?

thanks,

Chris.
  
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Premod70
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Re: max safe charge 38-55 IMR-4227
Reply #1 - Jan 17th, 2025 at 5:01pm
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Tell us what make/combination of rifle you are using.
  
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Re: max safe charge 38-55 IMR-4227
Reply #2 - Jan 17th, 2025 at 5:02pm
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Premod70 wrote on Jan 17th, 2025 at 5:01pm:
Tell us what make/combination of rifle you are using.


Modern highwall.  C Sharps.  GM barrel.

Chris.
  
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Re: max safe charge 38-55 IMR-4227
Reply #3 - Jan 17th, 2025 at 8:15pm
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Pressure wise, there's nothing to worry about, the barrel will lead, long before any pressure problems.

You can probably get to 20 gr before leading occurs, maybe more, you'll just have to try it.

If you have a chrono, I'd take the powder charge up, until I got to 1600 fps and see if accuracy holds up. 

You could get past 1600 with bullet hardness and wads but, accuracy and recoil are the things that will limit it.
  

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Re: max safe charge 38-55 IMR-4227
Reply #4 - Jan 17th, 2025 at 9:59pm
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Thanks.  I'm not looking for fast, but accuracy.  My 38-55's have all liked 18.0gr but I've never gone with higher charges.   That seems to give me about 1280 fps on my Magnetospeed.  I'll slowly take it up maybe another 0.5 to 1 full grain and see if it likes it.   

I have been digging through old posts and it looks like people have gone as low as 16gr.  I haven't tried quite that low but might explore those lower charges too.

Chris.
  
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Re: max safe charge 38-55 IMR-4227
Reply #5 - Jan 18th, 2025 at 2:33am
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The smallest groups I ever got with your combination was 19 grains. Was shooting an old Ballard. I think she was at her limit because I noticed screws were getting loose and she banged perty loud. Finally I must have hit one of them mysterious nodes you all talk about because she really grouped super good at 17.2 and the action didn't mind that at all. Your hiwall will take way more pressure but be careful. If the action sounds like an old barn door when opening, or if gas comes out and blows your buddies hat off or screws shoot out you know you've gone to far. If you can read Starline on the face of the breech block that would be a sign you got to much pressure. My own self, I tend to try different alloys. Soft medium and hard once the pressure is right. A bullet doesn't always have to go faster to be accurate. My mold tends to cast a bit small so I usually cast them about 40-1 or 60-1 so they will obturate out into the bore.  Below is a group from the Ballard with the RKS re-bored barrel. Ron Smith was spotting for me when I shot that group. No way I was giving that barrel back in a re-call.   
The bottom target was a twenty shot target. When I kicked about twenty shots on one target they told me to shut up and just shoot so I said okay but I'm not going to score it. I didn't score it either. I handed it to the Schuetzenmeister and told him, you score it smarty pants!
« Last Edit: Jan 18th, 2025 at 2:47am by westerner »  

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frnkeore
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Re: max safe charge 38-55 IMR-4227
Reply #6 - Jan 18th, 2025 at 2:46am
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A old, match winning load, from the '70's, into the '80's, with your bullet weight, was 18.5 gr 4759, with Rem 2 1/2 primers. Breech seated.
  

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Re: max safe charge 38-55 IMR-4227
Reply #7 - Jan 18th, 2025 at 8:51am
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what type of lube are you using, primers? what is your lead mixture? these are just questions because I might want to try some 4227 in my rifle.
  
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Re: max safe charge 38-55 IMR-4227
Reply #8 - Jan 18th, 2025 at 9:47am
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A tangential subject.

We shoot (3) 200-yard matches and maybe (12) 100-yard matches. My rifle is a Remington Rolling Block with a GM 1:12 full octagon heavy barrel. The bullet is a NOE 330-335-grain. Powder is IMR-4227, 17.0 grains. 

Changing yardage from 100 to 200 with the Unertl 24x scope takes a few minute to adjust the parallax. At our last match, after the 200-stage and wanting to return the parallax to 100, the lock ring would not budge. I gave up and sent it to an outfit in Tulsa to fix it. I do not overly crank on the lock ring to lock it after setting the scope to a new yardage. Still waiting for the scope to be returned to me.

My question....if recoil causes this, could recoil be strong enough to lock the lock ring so tight that it refuses to be loosened? Is there a way to prevent this in the future?

Thanks!

Tom
  
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Re: max safe charge 38-55 IMR-4227
Reply #9 - Jan 18th, 2025 at 1:25pm
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Thank everyone, that gives me plenty to think about.

Joe trying different alloys is something I hadn't even thought of, but it does make sense.  I generally order 20:1 and 16:1 from a local place.  I'm running low and about ready to order a bunch more and I think I'll get some 30:1 made up as well.

Chris.
  
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Re: max safe charge 38-55 IMR-4227
Reply #10 - Jan 20th, 2025 at 5:32pm
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Today I did a little more playing around with this rifle.  I tried a seating depth change and a little more powder.  At about 18.3gr (approximate as they were thrown from a Harrells measure and not weighed) I got it to shoot a 7 shot sub-moa group at 200m.  That's probably the limit of my eyesight and MVA aperture sights I think.  I'll shoot a few ten shot targets to see how it does before putting some scope blocks on it.

Later I'll try a softer alloy like Joe suggested.  With a scope I'm sure I could reduce the group size a bit too.

Chris.
  
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