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Greetings all.
Recently acquired a No 4 Mk II. Was concerned about what appears to be scorching on the face of the bolt head. First thing I did was order a field gauge from Okie Gauges. Have some resistance JUST before the bolt fully closes but would have to say at the end of the day it fails. Is this a headspace issue that caused the scorching? A new bolt head in order? The bolt head is a #1 that measures 631,5.
https://www.milsurps.com/images/impo...DSC03116-1.jpg
That bolt head looks normal to me
All of the bolt heads on all the rifles I have had look like that or worse
I have said this alot. head space on the 303 is dependant on the rim and as rim thickness varies between brands and batches of brass so the head space will vary accordingly. Head space the rifle to the brand of ammo you are using. The measurement for military head spacing allows for various rim thicknesses and an allowance for dirt.
I have owned close to 80 303 rifles and never had a head space issue with any of them except 2 which 1 had a mismatched bolt and for that I had to change the bolt body for alonger body to get it right.
Check the MKL for a nice article by Parashooter on head spacing .. ;)
Headspace 101 for .303's (click here)
Regards,
Doug
Good article, thanks Doug. I had seen that but wasn't sure if what I was seeing on the bolt face correlated to a headspacing issue, especially after it failed the field gauge. Guess I expected the bolt to offer more resistance well before it did since it is a relatively 'new', all matching '55. I have some Mosin's that haven't come close to where I got the bolt on the gauge so there was some initial panic. After doing a little more reading I have a couple of boxes of Prvi that I feel pretty confident running through it.
Thank you both for the quick responses!
Have the same ring on my No4 mark2, always thought someone didn't clean the bolt head properly after shooting corrosive ammo.
If it's a .074 gauge and it's got resistance before closing, I'd guess it's probably OK and I'd keep the screws tight and just enjoy it. Remember that emergency use standard was .084. The ring on the face where the primer gas hits is normal.
Are you sure you're not getting pierced primers? It looks like excessive firing protrusion on this bolt...
pierced primers would burn the riring pin and around the firing pin hole in the bolt headQuote:
Originally Posted by browningautorifle
the ring on this bolt head is normal for gas leak around the .250 berdan primer found in cordite surplus ammo