Yesterday's Weapons Forums

Discussion of history's firearms
It is currently Mon Oct 23, 2017 8:35 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Wed Oct 19, 2016 5:39 pm 
Offline
Gunnery Sergeant
Gunnery Sergeant
User avatar

Joined: Mon Jul 23, 2012 5:14 pm
Posts: 212
Location: Oshawa
The primers are being set back with my Chilean 1912 Mauser. Probably all of my reloads and 16 out of 20 new S&B FMJ. Maybe 1 to 2/100ths. This isn't happening in my Ken Ball Custom Mauser, just the Chilean, so I'm thinking it is the gun and not primer pockets wearing away with reloading.

I don't recall this happening when I first got the gun.

One fix suggested was to have a gunsmith reface and re-seat the barrel just that 1 or 2/100ths deeper. (I assume the 'reface' part is because it is eroding over time?) But doesn't the round index on the shoulder? And even if it indexes on the neck/mouth isn't it the chamber that it indexes against, not the barrel? The chamber is part of the action isn't it? Not part of the barrel?

I wondered if the locking lugs could have worn just enough that the bolt doesn't seat properly against the cartridge. Or is it possible to turn the bolt handle 'almost' closed? Maybe on those 4 factory loads that the primer didn't shift I had snugged the bolt tight?

Is it possible to shim/build up just the 3/8" dia. centre of the bolt, just the part that should be pressing against the primer?

Or is 2/100ths too small to worry about? Just keep shooting and see if it grows to 3/100ths or more?

_________________
Them that know, know that they know. Them that don't know don't know they don't know.


Top
 Profile  
 
PostPosted: Wed Oct 19, 2016 7:20 pm 
Offline
Теперь предлагаем бесплатную ежедневную маммографию!
Теперь предлагаем бесплатную ежедневную маммографию!
User avatar

Joined: Sun Aug 05, 2007 9:04 pm
Posts: 7810
Location: North Antelope Coal Mine
Before investing big money in a gunsmith, you could try fireforming cases to that specific rifle.

Using the longest bullets available, seat them out to touch the rifling. When you fire, the case will expand to fill the chamber. (Light loads for this!)

You are then in a neck size only situation, though. SW

_________________
Darkness is all around us and enemy are just beyond the perimeter.


Top
 Profile  
 
PostPosted: Fri Oct 21, 2016 12:42 pm 
Offline
The Knife
The Knife
User avatar

Joined: Sat Aug 04, 2007 3:15 pm
Posts: 3404
Location: Bean town in the worthless nut state
The chamber is in the barrel. .020 is a lot of headspace. When you have a barrel set back they usually do a full thread to keep sights in line. Another way in to expand the neck then using your sizer back off a turn and size case neck till the bolt just closes on it Then is is neck size for that rifle only.

Rad

_________________
Image

NRA Benefactor Member
AMA Life Member
Tri-State Gun Collectors Life Member


Top
 Profile  
 
PostPosted: Fri Oct 21, 2016 2:34 pm 
Offline
Теперь предлагаем бесплатную ежедневную маммографию!
Теперь предлагаем бесплатную ежедневную маммографию!
User avatar

Joined: Sun Aug 05, 2007 9:04 pm
Posts: 7810
Location: North Antelope Coal Mine
Rad's way is better. SW

_________________
Darkness is all around us and enemy are just beyond the perimeter.


Top
 Profile  
 
PostPosted: Fri Oct 21, 2016 3:33 pm 
Offline
Gunnery Sergeant
Gunnery Sergeant
User avatar

Joined: Mon Jul 23, 2012 5:14 pm
Posts: 212
Location: Oshawa
HerrMesser wrote:
The chamber is in the barrel. .020 is a lot of headspace. Rad

So I'm right to worry about this? I.E. don't keep shooting until this is fixed?

HerrMesser wrote:
When you have a barrel set back they usually do a full thread to keep sights in line. Another way in to expand the neck then using your sizer back off a turn and size case neck till the bolt just closes on it Then is is neck size for that rifle only.
Rad

I'm not clear on what you're saying.
Should I expand the neck WIDER than the 7mm and then keep trying it in the gun and readjusting the sizer until the bolt just closes on it? With or without a bullet seated?
If this is with a bullet seated couldn't I get the same result just by loading 0.02" longer than recommended? (And when that round is fired the shoulder is fire formed forward that little bit.)
Is it the bullet, the mouth/neck, or the shoulder that 7mm Mauser indexes on?

Is what I am trying to do here is move the shoulder forward until the cartridge "backs up" that 0.02"?
And having done this, never use factory ammo again, because factory ammo won't have that "forward set" shoulder? (at least until I spring the megabucks to have the barrel reseated)

_________________
Them that know, know that they know. Them that don't know don't know they don't know.


Top
 Profile  
 
PostPosted: Fri Oct 21, 2016 5:00 pm 
Offline
Теперь предлагаем бесплатную ежедневную маммографию!
Теперь предлагаем бесплатную ежедневную маммографию!
User avatar

Joined: Sun Aug 05, 2007 9:04 pm
Posts: 7810
Location: North Antelope Coal Mine
Expand a case to 8mm. The bolt shouldn't close. Then run the case into the 7mm FL die... a little at a time... until the bolt will barely close.

When you fire, the shoulder will be moved forward to fill the chamber, and headspace will be corrected - for that rifle only. Neck size only for that specific rifle.

My method of seating the bullet out to touch the rifling does the same thing, but Rad's way gives more consistent results.

Further... when the barrel is set back a full thread to keep sight alignment right, it will have to be rechambered. SW

_________________
Darkness is all around us and enemy are just beyond the perimeter.


Top
 Profile  
 
PostPosted: Fri Oct 21, 2016 6:47 pm 
Offline
Gunnery Sergeant
Gunnery Sergeant
User avatar

Joined: Mon Jul 23, 2012 5:14 pm
Posts: 212
Location: Oshawa
NebrHogger wrote:
Expand a case to 8mm. The bolt shouldn't close. Then run the case into the 7mm FL die... a little at a time... until the bolt will barely close.

When you fire, the shoulder will be moved forward to fill the chamber, and headspace will be corrected - for that rifle only. Neck size only for that specific rifle.

My method of seating the bullet out to touch the rifling does the same thing, but Rad's way gives more consistent results.

Further... when the barrel is set back a full thread to keep sight alignment right, it will have to be rechambered. SW


Thanks Steve.

I don't have an 8mm die but I used the Lee neck expander to put a definite visible 'bell' on the mouth. It wouldn't go deeper, just a 100th or so. Probably just as well since the neck expander continues to taper wider and wider.

Anyway, with that bell, the bolt wouldn't close.

Tried the proper FL die until the bolt would close. (The die is so far out the bottom doesn't reach the bottom of the die holder!)

Pressed in a bullet just with my fingers. It grips. Probably if I used the press to seat it to the proper depth (3.06") it would sit with the cannelure just out of sight.

So, so far so good. But I'm left with a case with a slightly belled mouth and a definite 'waist' in the neck between the mouth and the shoulder. (Again, if I seat the bullet that waist will be reduced as the bullet presses the neck out.) Is this what I should be seeing?

I can't test it until I pick up some more .284" bullets and get out to the range. (I don't know why but the fuzz seem to object to anyone test firing a rifle in a 100' deep yard in city limits!)

Using my cheap plastic calipers I get:
case mouth approx .345 (vs .320 spec.)
case neck approx .32 (right on spec.)
case neck I.D. .28 something (no spec. given, but bullet dia. is .284)
case mouth I.D. looks like .295"

I'll have to pick up some Hornady 175 gr RN #2855 and load maybe 10 over 35.0 gr 4064 and 10 over 36.8gr. Might as well stay with the same loads as were showing the problem. My Barnes C.O.W. shows 39 grains 4064 for 2450fps.

Edit: the 'same loads' were Hornady #2845 162gr RN.

_________________
Them that know, know that they know. Them that don't know don't know they don't know.


Top
 Profile  
 
PostPosted: Sun Oct 23, 2016 6:45 pm 
Offline
Staff Sergeant
Staff Sergeant

Joined: Thu Dec 05, 2013 10:58 pm
Posts: 199
In his book 'Modern reloading" (I think that's the title) Richard Lee gives one of the causes of primer backout as being not enough powder in the case. I had this problem in my Arisaka carbine. Added a grain extra powder and the problem went away.
In any event, this isn't a good thing to have going on. A quick resolution is what is needed.

_________________
David

"We are not interested in the possibilities of defeat; they do not exist"
Victoria 1899


Top
 Profile  
 
PostPosted: Wed Nov 16, 2016 10:29 pm 
Offline
Gunnery Sergeant
Gunnery Sergeant
User avatar

Joined: Mon Jul 23, 2012 5:14 pm
Posts: 212
Location: Oshawa
Well I finally got some rounds modified and loaded and got out to the range. No primer backout at all. But also no backout on rounds the I had loaded a year ago and didn't go through the expanding the neck and then carefully bringing it back to 7mm. And I really had to eat my Wheaties to seat these primers. They were really tight. I'm now wondering if the problem originally arose from maybe having a different brand of primers, possibly infinitesimally smaller than standard? God knows I've got several different brands coming with an auction lot when I'm bidding on something else in that lot. The ones I used this time were CCI number 200's.

Anyway, it's all good now!

Thanks guys.

_________________
Them that know, know that they know. Them that don't know don't know they don't know.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB® Forum Software © phpBB Group