.358 Norma

[270Weatherby]

I'm having issues with a new .358 Norma. Douglas barrel on a new Win action... The first loadings are not showing any pressure signs, but the second or third loading ends up with a sticky bolt. Same load...(IMR 4350 74gr. under 250gr partition Fed215m 2700fps). Why am I getting pressure on the 2nd loading but not on new brass? How can I fix this?

Also, chrono Double Tap factory loads with 225gr Accubonds at 3050! No pressure. I can't come anywhere near this type of speed. What gives here?

 

[65WSM]

I e-mailed a friend with a .358 Norma.

Remember that IMR 4350 was developed after WWI for the 50 BMG. I would be trying new double base powders for velocity. The Superperformance has the same burn rate as IMR 4350. Hunter is also in this range. My guess is that burn rate 4831 on the IMR scale would better suit 250 gr bullets. 4000MR or MagPro would result in more velocity.

The pressure can come from multiple sources. First eliminate the rifle. Is copper building up. Partions will build copper. Clean with Sweets.

The brass may be flowing because of a generous chamber. Are they too long for the chamber. One time I had to turn the necks of a .270 Weatherby put together by MacBros when they were starting out because the chamber neck was tight but the body was long. The brass flowed into the neck and thickened. After turning I had no other issues.
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[65WSM]

Hi Warren

I was just in Sitka at Tony's and shot my 358NM. Still as accurate as ever.
I load 74.7 grains of H4350 with Federal 215 standard primers pushing a 250 grain Hornady Interlock SP at 2725 fps at 1000 ft elevation.
If I do my part it puts 3 shots in one ragged hole at 100 yards.
It is an Enfield 1917 Winchester action unknown barrel 21.75 inch, 6 groove, 1/16 twist. I am using Norma 358NM stamped cases.

I tried several powders and the H4350 gave me the best accuracy and spread variance in this particular gun.
It has been my experience that maximum accuracy is "not" obtained at maximum speed in this caliber.

Absolutly trim the cases uniform and at least .010 shorter than the chamber, also I have found that I must always full length resize to obtain reliable feeding in my gun.
The factory loads use there own recipe for powder normally. I have read they evern use blended powder. So it is pretty hard to analyze factory loads. And or compare to handloads. My best guess is a lot of head expansion on the brass on the first firing, thus the full length resize suggestion.

Hope this helps.

 

[65WSM]

I e-mailed a friend with a .358 Norma.

Remember that IMR 4350 was developed after WWI for the 50 BMG. I would be trying new double base powders for velocity. The Superperformance has the same burn rate as IMR 4350. Hunter is also in this range. My guess is that burn rate 4831 on the IMR scale would better suit 250 gr bullets. 4000MR or MagPro would result in more velocity.

The pressure can come from multiple sources. First eliminate the rifle. Is copper building up. Partions will build copper. Clean with Sweets.

The brass may be flowing because of a generous chamber. Are they too long for the chamber. One time I had to turn the necks of a .270 Weatherby put together by MacBros when they were starting out because the chamber neck was tight but the body was long. The brass flowed into the neck and thickened. After turning I had no other issues.
​

 

[Lefty7mmstw]

Is your belt or lower part of the case swelling. I've seen that make stout loads act like they are over pressure in older brass.

 

[270Weatherby]

Thanks for the help.
I am full length resizing.
Above the belt has no measurable changes before or after firings. The resized loads slide in fine. They have a sticky bolt after firing. The wierd thing is this doesn't happen with new brass. only once or twice fired. Is the brass just too soft?

 

[Lefty7mmstw]

I've had your sticky brass thing happen on rifles before. The brass has farther to expand when it new and each succesive firing produces somewhat less rebound, even with full length resizing, as you aren't using a small base die. Less tolerance and things start to interfere once in a while. You may have a bit of a sharp edge or burr at the rear of the chamber just above the belt. You need to look for interference on the brass-- scraping, etc. for the chamber burr issue. I've had it more than once and it always manifests after the first firing on a belted mag. It could even be build up in the chamber if this has gone on for a bit, so check that too.

 

[270Weatherby]

Thanks,

I'm thinking the die is just a little too big or the reamer was just a little too tight. The contact points are up around the shoulder. (I used a candle and blacked the brass.) I hate to go try another brand of die, another $80 or more. I have always liked the Redding dies, but maybe I need to go to RCBS or Hornady?

 

[Lefty7mmstw]

Thanks,

I'm thinking the die is just a little too big or the reamer was just a little too tight. The contact points are up around the shoulder. (I used a candle and blacked the brass.) I hate to go try another brand of die, another $80 or more. I have always liked the Redding dies, but maybe I need to go to RCBS or Hornady?

If the contact point is on the shoulder, you should be able to stop the interference if you turn the die down a bit more, as long as you aren't camming over already. If you already have the die down all the way, a small base die or a look at the chamber by your 'smith with a reamer are probably your best two options. Die make probably won't help much. Are small base dies even around for the 358??

 

[Lefty7mmstw]

I'm having issues with a new .358 Norma. Douglas barrel on a new Win action... The first loadings are not showing any pressure signs, but the second or third loading ends up with a sticky bolt. Same load...(IMR 4350 74gr. under 250gr partition Fed215m 2700fps). Why am I getting pressure on the 2nd loading but not on new brass? How can I fix this?

Also, chrono Double Tap factory loads with 225gr Accubonds at 3050! No pressure. I can't come anywhere near this type of speed. What gives here?

2700 fps is just about perfect for a 338 or 358 with a 250. I get just about that with my #1 in 338 with the sierra. A 225 will do 2900 fps with no trouble with rl19 in my 338, but 250's can't go that fast. I haven't pushed to see how fast, as 2900 is already enough recoil in an 8# 338 with no brake and no soft pad. It shoots so well, I'm loath to change it.

 

[270Weatherby]

Sent brass and dies into Redding. They figured out there was some chatter with the reamer. So there are small ridges in the chamber.
Those guys at Redding are awesome. Glad to know there is still good customer service out there.

 

[Lefty7mmstw]

Sent brass and dies into Redding. They figured out there was some chatter with the reamer. So there are small ridges in the chamber.
Those guys at Redding are awesome. Glad to know there is still good customer service out there.

So, what's your plan for the chamber??

 

[270Weatherby]

Good question. The smtih said he would polish it out, but everything I've read says you need to re-cut the chamber (and shorten the barrel). I haven't decided what I'm going to do yet. Double Tap has some impressive ballistics and cost.

 

[Lefty7mmstw]

I hear a 358 sta calling. That will clean out the iffy part of the chamber and give you 338 ultra snort to boot. Depends on how much recoil you want to take, it might need a brake.