[philthephlier]

I have a Savage #4 Mark I with headspace issues. Fires a fresh Winchester case fine but separates on the next firing. I saw a thread about some smart Canucks that use O-rings against the rim of a new case to force the case head against the bolt face, thus forcing the case to form forward to the shoulder. They claim it works great so I will try it tomorrow. I found a package of 10 size 7 O-rings in the plumbing section of Home Depot for $.97.
Size 7 is 1/2" OD and 3/8" ID. They stretch nicely over the case and seat well against the rim. I tried a new empty case in the chamber with one and the bolt locks up nice and snug. I'll post again with the results. Thanks in advance to whoever thought of the idea and then tried it sucessfully.
PS How many cases will an O-ring form before giving up the ghost?

 

[Edward Horton]

The o-ring as a spacer works very well and the Canadians thought up a winner with this one (No duct tape)

I use high pressure aircraft grade o-rings so they will last longer (Aim High Airforce)

The spacer idea has caught on and you no longer need to use resizing lube on your cases which increases bolt thrust.

http://parallaxscurioandrelicfirearmsforums.yuku.com/topic/3361

 

[Calgacus]

It's basically a good technique, but as those O-rings are presumably 1/16in. thick in the fore and aft direction as well as sideways, I would hope that most of these 65.5 thousandths of an inch are being taken up by squeezing rubber out at the sides.

If the actual headspace excess is more than a small fraction of that figure, they are rather large headspace issues. It would be a good idea to substitute a longer bolt-head, and if they don't exist long enough, examine the rifle carefully to see WHY it has such headspace issues. If a rifle's headspace has increased more than a couple of thousandths in use, it may be because of some past abuse that could be dangerous in the future.

 

[ditch68]

I am completely ignorant of reloading and brass resizing, etc, issues, but I read this and was giving it some thought. I don't reload yet, but would like to delve into it.

Wouldn't placing an o-ring, presumably rolled down the case to the cartridge rim in order to take up excessive headspace, artificially set the case head rearward (yes, I know, that's the point), but with potentially adverse effects? I thought headspace was a finite measurement which was a relative expression of the bolt face to the case head (rear), taking into account the specifics of the chamber, relative to the brass cartridge plus rim thickness. I.E., case and rim thickness being a given, the chamber shoulder to boltface distance is "headspaced" via bolt head exchange or fitment for an Enfield (or bolt body exchange in a Mauser action) to achieve the proper boltface-to-chamber shoulder length, with the aim of avoiding stretch, and ultimately case head seperations?

Now, with a cartridge case like the .303, with such a tapered case body, I would think this o-ring solution would subject the case to the possibility of improper seating of the casewall in the chamber, thus causing radial stretching of the cases as they fireformed to the chamber. Or linerar stretching which would weaken the shoulder of the case?

Please explain why not, or if so, why it is acceptable, and how many reloads this will endure. This is new to me, but I am curious!

Jeff

 

[Edward Horton]

I’ve been reloading for over 40 years and was tutored in my early days by a machinist and bench rest shooter, this means tight head space and tight chambers. As a reloader one of the things that makes me a little tight jawed is the phrase “.074 is good enough for me” because our American made cases are on the small side in the base web area and in rim thickness.

I have a South African marked 1950 Mk.2 that was centered bedded by the South Africans and I replaced the bolt head and have the head space set tighter than the minimum of .064. (My bolt will not close on a .064 head space gauge)

A war broke out over my head space views four years ago and a few people still want to have me castrated, hung, drawn and quartered and loose all internet privileges. BUT if you notice at Mr. Parashooters head space 101 you no longer see anything about using resizing lube to fire form your .303 cases. (I’m explaining this because of Calgacus uncalled for comments in another posting)

In the book below it states to set your head space .003 (three thousandths) over rim thickness and it was written by Skennerton and Labudda. Note, one of my favorite sayings is “All the information in the world is written in books and all you have to do is read”

My first Enfield wears a # 3 bolt head the headspace is approximately .067 and Winchester cases start to separate after three firings, and this is due to the case construction of our American made cases. (I now use only Remington commercial cases)

On this Enfield I use the o-rings to fire form the cases and have had no problems after two reloadings. I have a RCBS Case Mastering Gauge and can measure the thinning in the web area very accurately after each firing.

In my opinion for the people who reload the best thing to do is push the case as far into the chamber as possible and forget the published head space setting to reduce head gap clearance and prevent the stretching in the web area, this depends on the type or make of cases you reload and how fat or the diameter of the chamber.

I just bought 500 once fired Greek HXP cases from Brian at http://www.bdlltd.com/ and I’m amazed because NONE of these 500 cases have ANY thinning in the web area and they were shot from two different machine guns and several different Enfield rifles.
(I’m assuming our American made cases do not have enough Oúzo in the brass mixture)

To ditch68, yes the o-rings push the case to the rear and into contact with the bolt face, but this prevents or reduces any case stretching in the web area on the first firing. The downside to this is more case expansion outward to meet the chamber walls and the possibility of ending up with a warped banana shaped case. A warped banana shaped case is a case that expands more on one side than the other when fired and when the case tries to “springs back” to its original shape the base of the case becomes off center and is no longer 90 degrees to the axis of the bore.

The o-ring is for people who can’t decrease head space for what ever reason and do not want any thinning in the web area.

Below are the latest headspace settings from the 2002 Canadian No.4 manuals and this is for shooting the case once and not reloading it, I take these settings to read as:

GO - .064
NO-GO - .070
FIELD - .074