375 H&H Virgin Brass Stretch

Bob Nelson 35Whelen said:

@LeftySixgun
The tool I use is the brain
If my cases be they rimless or rimmed become hard to chamber I trim to length then full length size until I have very slight resistance when I close the bolt. This is done by sizing the case in very small increments

@Hunter4752001
Unfortunately you can't headspace off both the belt and shoulder. I agree with your initial assessment on the design but the position of the belt can vary from brand to brand and chamber dimensions are different for every rifle regardless of calibre. For rimless and magnum cases you should always headspace off the datum line in the shoulder.
Bob

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Bob,
Thank you for your comments and observations.
Concerning headspacing off the shoulder, once you have determined that a case fits your particular rifles chamber by sizing the case in very small increments and testing it in your chamber, then every case you resize for that particular rifle will be the same, right? At that point if you measure the case to the shoulder and record that dimension in your notes, then you should be able to just resize all the cases for that rifle to your recorded dimension. Are you removing the striker/firing pin from the bolt when you are determining by feel the case case dimension you are seeking? The resulting rounds loaded using your method are only usable in one particular rifle. Therefore, if you have more than one rifle in that caliber you have to be careful not to mix the rounds up for each rifle.
Thanks again for sharing your information.

RSL said:

Bob,
Thank you for your comments and observations.
Concerning headspacing off the shoulder, once you have determined that a case fits your particular rifles chamber by sizing the case in very small increments and testing it in your chamber, then every case you resize for that particular rifle will be the same, right? At that point if you measure the case to the shoulder and record that dimension in your notes, then you should be able to just resize all the cases for that rifle to your recorded dimension. Are you removing the striker/firing pin from the bolt when you are determining by feel the case case dimension you are seeking? The resulting rounds loaded using your method are only usable in one particular rifle. Therefore, if you have more than one rifle in that caliber you have to be careful not to mix the rounds up for each rifle.
Thanks again for sharing your information.

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@RSL
I leave the rifle as is with firing pin and everything. If it's a push feed I use an empty cas.
In a crf I remove the bolt and slide the empty case under the extractor and reinstall the bolt.

ALL RIFLES ARE DIFFERENT.
My mate has 2 rifles of the same brand and if you only neck size the cases they will not interchangeable between rifles.
That's why I only have ONE rifle in the calibre I like.
Once you have your cases sorted instead of changing the setting each time just use a neck sizing die like the Lee collet die. That way you only have to fly every 5 or so loads depending on how hot you load.
Bob

Bob Nelson 35Whelen said:

@RSL
I leave the rifle as is with firing pin and everything. If it's a push feed I use an empty cas.
In a crf I remove the bolt and slide the empty case under the extractor and reinstall the bolt.

ALL RIFLES ARE DIFFERENT.
My mate has 2 rifles of the same brand and if you only neck size the cases they will not interchangeable between rifles.
That's why I only have ONE rifle in the calibre I like.
Once you have your cases sorted instead of changing the setting each time just use a neck sizing die like the Lee collet die. That way you only have to fly every 5 or so loads depending on how hot you load.
Bob

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I am a big fan of the Lee Neck Sizing Die.

I shoot and load for my Heym Express 375 H&H very often. My rifle will put Barnes TSX bullets into less than an inch at 100 with boring consistency (my rifle loves H4895, so the OP is on the right track).

The 375 H&H, with its long and tapered case and quaint shoulder is made to feed smoothly. A tradeoff for the smooth feeding is case life. Don't worry about measuring to the thousandths of an inch when bumping shoulders, just full length size, load and shoot. Keep track of your trimmings and firings, I throw my brass away when case length exceeds max and has already been trimmed twice.

This post got me curious about my current 300H&H project. Ran 40 rounds of HSM box ammunition through the new barrel then start load development. Using Nosler prep'd brass which is surprisingly consistent in brass length. Just measured fired brass versus unfired. The brass grew .019 in the shoulder, but did not grow in OAL showing the same variance that the unfired brass shows +/- .001. My plan from everything I have read has always been to headspace off the shoulder as Bob suggested above. Perhaps this is normal for the H&H cartridges?

PS Makes me wonder how much influence this amount of brass stretch on first firing has on group sizes and ES.

I have been mulling over the headspace issue with my 375 H&H. It has become apparent to me that regardless of what is done about the case shoulder the case will still headspace off the belt. If the case base and the belt are not modified how will the round headspace from the shoulder? The bolt to chamber dimensions that control the case headspacing off the belt do not change and the case base to the belt dimensions do not change a measurable amount. So the best, IMO, that might happen is the case fitting rhe chamber EXACTLY from the belt to the shoulder. Or very close to it. OK, i have climbed out here on a limb with my theory. I expect the experts here will saw it off!!!

RSL said:

I have been mulling over the headspace issue with my 375 H&H. It has become apparent to me that regardless of what is done about the case shoulder the case will still headspace off the belt. If the case base and the belt are not modified how will the round headspace from the shoulder? The bolt to chamber dimensions that control the case headspacing off the belt do not change and the case base to the belt dimensions do not change a measurable amount. So the best, IMO, that might happen is the case fitting rhe chamber EXACTLY from the belt to the shoulder. Or very close to it. OK, i have climbed out here on a limb with my theory. I expect the experts here will saw it off!!!

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Exactly. The whole point of the belt was to solve the issue of a short neck coupled with the shallow shoulder angle of a 375 H&H case. The designers realized that it couldn't reliably headspace on the shoulder so they added the belt for reliability; similar to rimmed cartridges but still reliably feed from magazine rifles.

RSL said:

I have been mulling over the headspace issue with my 375 H&H. It has become apparent to me that regardless of what is done about the case shoulder the case will still headspace off the belt. If the case base and the belt are not modified how will the round headspace from the shoulder? The bolt to chamber dimensions that control the case headspacing off the belt do not change and the case base to the belt dimensions do not change a measurable amount. So the best, IMO, that might happen is the case fitting rhe chamber EXACTLY from the belt to the shoulder. Or very close to it. OK, i have climbed out here on a limb with my theory. I expect the experts here will saw it off!!!

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@RSL
What you say is partially correct but
Belt size and position can and do vary slightly from brand to brand.
Rifle chamber dimensions vary as the reamer gets worn.
Combined these two things can vary head space considerably resulting in case head seperation .

The same with rimmed cases that are supposed to headspace off the rim. Rim thickness varies
My 22K Hornet chambers most brass but RWS case will not allow the block on my lowall to close because the rim is to thick. My rifles that use rimmed cases are head spaced off the brand of brass I use and I also use the datum line on the shoulder. 303 cases can vary from .058- 062 in thickness. As you can see if you use cases with thinner rims you may already have a .004 difference then ad bumping the shoulder back .002 and you end up with .006 headspace which will very likely cause head seperation.
The only 100% sure way in my book is the shoulder datum line in your fired cases. That way the case is sized to suit YOUR RIFLE.
Bob

@Bob Nelson 35Whelen
My concern is the .017 inch "stretch" when firing my virgin Norma Brass the first time in my rifle.
I am interested to see if the second firing causes additional "stretch".

My premise in my last post, #26, is that the case headspaces on the belt and that dimension does not change when the round is fired. Therefore, in all likely hood if i bump the shoulder back .002 on fireformed brass the case will still be headspacing off the belt. But, the case will not be "stretched" like virgin brass. We may be saying the same thing and it's just semantics.

I will look at a SAAMI drawing tomorrow to learn the headspacing tolerances for the cartridge and chamber.

RSL said:

@Bob Nelson 35Whelen
My concern is the .017 inch "stretch" when firing my virgin Norma Brass the first time in my rifle.
I am interested to see if the second firing causes additional "stretch".

My premise in my last post, #26, is that the case headspaces on the belt and that dimension does not change when the round is fired. Therefore, in all likely hood if i bump the shoulder back .002 on fireformed brass the case will still be headspacing off the belt. But, the case will not be "stretched" like virgin brass. We may be saying the same thing and it's just semantics.

I will look at a SAAMI drawing tomorrow to learn the headspacing tolerances for the cartridge and chamber.

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I was told years ago by my gunsmith friend (when I built my 458 wind bag) that he had worked on a factory 338 that kept having case head separation problems with certain brass. He worked out that the numerous different brands of brass, and different batches of the same brand, had up to 0.010” variations in belt headspace position with the sloppy chamber in the rifle, his cheap repair option was for the owner to headspace off the shoulder and to ignore the belt and rechamber it (setback) at a later date
Gumpy

Ive wanted to do this but never have. Seems like all the discussion of this thread it seems appropriate to try.
Take one piece of virgin brass and see how many times it can be loaded before it fails and where it fails. The only brand of brass I have is Hornady. And just my feeling, I think I have a pretty good chamber dimensionally. The brass that comes out of my Sako 375 H&H will not chamber in my Winchester.
Anyone else curious about this?

Based on my experience failure happens quicker if the chamber is more generous.
My pre-64 M70 375 H&H has a larger chamber than my Kimber:
Fired brass from the M70 will not chamber in the Kimber.
Fired brass from the Kimber will chamber in the M70.

I found that Hornady brass failed as early as 3 firings from the old M70. The closest to full failure I saw was a hairline crack just above the belt that didn't leak any noticeable gas (case head separation).
I started studying these cases in good light (outdoors is best) and you can see a bright "frosted" ring that occurs before a crack occurs.
Now I toss the brass when I see this ring at the case head.

This process occurred more slowly with the Kimber and now that I set my dies to almost full length size without bumping the shoulder my brass life has been a non issue. I also switched to Norma brass which probably helps.

RSL said:

Some of you may have seen my previous thread about my first time firing my M70 Classic Express. I am just now getting around to checking the brass from that range day. I fired virgin Norma brass I handloaded with 58.6g H4895 powder and Hornady 270g Interlock bullets. The virgin Norma brass measured 2.455 inches from the case bottom to the shoulder datum. The once fired brass measured 2.4712 inches from the case bottom to the shoulder datum. That's a difference of plus .017 inches. More than i expected. I am trying to figure out how much if any i should bump the shoulder back when i resize this once fired brass. The once fired brass loads into the chamber ok as it is. No resistance when closing the bolt. I am open to suggestions. TIA.

Stan

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These help a lot in getting the right fit. Can check around on the price. I just snagged it for the picture.

Accidental Villain said:

I think you are pretty much spot on there.
I`ve zeroed a number of 375 H&H rifles for customers back in the day with different kinds of ammo.
This is one of the great party tricks of the 375H&H. You can sometimes make it work with a combination of bullets without changing zero that is, provided factory spec cases I guess? I`ve never tried it with anything else. Like a combo of 300 grain FMJ/SP and for example 270 grain SP.
Because the 375H&H head-spaces on the belt the bullets will usually hit the rifling at the exact same angle provided factory spec cases.
For hunting I`ve always sized the cases to exact cartridge specs. Shorter case life yes I know, but its for hunting so who cares.

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Spot on Accudental Villain
50 yrs ago I shot a lot of 375
Factory 270 & 300 shot to point of aim at 0-200 yds with good old Remington Core-Locked round nose . My personal experience
As for cases , my main concern was stretch just foward of the belt ( just like 7mm REM Mag)
Be most diligent in inspecting your brass just forward of the belt !!!!!! That gain in case length most probably had a component of belt area stretch . Poor chamber tolerances don’t help either.
Case stretch at the belt is that lighter color band of bass just forward of the belt.
All cases can vary in wall thickness . Bumping the neck to shorten the length can’t repair the belt area stretch
One thing you Do Not want to experience is a case failure at the belt at 60,000psi
I am not hunting or shooting my last 375 at this time so I’m not up to snuff on new case specs.
Please look at your factory fired bass. Note any light stretch ring on once fired cases and compare your cases Visual insp at the belt ring
Any stretch ring getting to wide- retire the case.
It is a safety issue on this high ctg
I used and sighted for REM factory 270/300 therefore no chambering concerns in the field

Accidental has some very good points here.

Bush Buck said:

Based on my experience failure happens quicker if the chamber is more generous.
My pre-64 M70 375 H&H has a larger chamber than my Kimber:
Fired brass from the M70 will not chamber in the Kimber.
Fired brass from the Kimber will chamber in the M70.

I found that Hornady brass failed as early as 3 firings from the old M70. The closest to full failure I saw was a hairline crack just above the belt that didn't leak any noticeable gas (case head separation).
I started studying these cases in good light (outdoors is best) and you can see a bright "frosted" ring that occurs before a crack occurs.
Now I toss the brass when I see this ring at the case head.

This process occurred more slowly with the Kimber and now that I set my dies to almost full length size without bumping the shoulder my brass life has been a non issue. I also switched to Norma brass which probably helps.

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Bush Buck is right on
Belted brass , variances of factory chambers and head space takes a toll on brass
For me , here in the US , I shot factory ammo Corelocked round nose . Please note I never had to face a pissed off Cape buffalo

450 Dakota said:

These help a lot in getting the right fit. Can check around on the price. I just snagged it for the picture.

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Thanks, I have and use those shell holders.

LeftySixgun said:

Ive wanted to do this but never have. Seems like all the discussion of this thread it seems appropriate to try.
Take one piece of virgin brass and see how many times it can be loaded before it fails and where it fails. The only brand of brass I have is Hornady. And just my feeling, I think I have a pretty good chamber dimensionally. The brass that comes out of my Sako 375 H&H will not chamber in my Winchester.
Anyone else curious about this?

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If i were younger i would def be interested. But, as i posted, i am an old fart, and don't think i will be shooting my M70 375 H&H enough to use up the 100 pieces of Norma brass i have on hand.

RSL said:

If i were younger i would def be interested. But, as i posted, i am an old fart, and don't think i will be shooting my M70 375 H&H enough to use up the 100 pieces of Norma brass i have on hand.

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lol, I’m trying to get good use out of my 1st 100pcs of brass

LeftySixgun said:

Ive wanted to do this but never have. Seems like all the discussion of this thread it seems appropriate to try.
Take one piece of virgin brass and see how many times it can be loaded before it fails and where it fails. The only brand of brass I have is Hornady. And just my feeling, I think I have a pretty good chamber dimensionally. The brass that comes out of my Sako 375 H&H will not chamber in my Winchester.
Anyone else curious about this?

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@LeftySixgun
That's what I have been saying all thru this post.
Unless cases are full length sized they may not fit another rifle. Neck sizing makes a cartridge fit the chamber it was fired in only.
I have cases that have been reloaded north of 15 times. CSes will last a long time if treated properly.
There's a person I read about that buys a new rifle and 100 rounds of ammo. When the cases come to the end of their life he sells the rifle because the barrel is worn to much for him. He gets well north of 20 loads per case so in excess of 2,000 shots.
Bob

LeftySixgun said:

Ive wanted to do this but never have. Seems like all the discussion of this thread it seems appropriate to try.
Take one piece of virgin brass and see how many times it can be loaded before it fails and where it fails. The only brand of brass I have is Hornady. And just my feeling, I think I have a pretty good chamber dimensionally. The brass that comes out of my Sako 375 H&H will not chamber in my Winchester.
Anyone else curious about this?

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I think that's pretty normal. I have two 6.5PRCs the barrels for both were chambered by the same gunsmith (of high repute), same reamer. Both barrels are Benchmark, one is carbon, one is steel. The actions are Lone Peak, one a Fuzion, one a Razor. Both have the same tenon dimensions. The barrels and actions are interchangeable, all combinations headspace perfectly using go and no-go gauges. Brass from rounds fired in the steel barrel will not chamber in the carbon barrel without resizing, but vice versa they do chamber.