Cast Bullets for 2 groove bbl #4MKI*

Morning all. Looking for suggestions for heavy cast bullets 2 groove barrel on my longbranch #4MKI*. This rifle is not in its origional military shape. Has had the top handguards removed, forend shortened, barrel cut to 22", and a parker hale sporting front sight ramp installed. Headspace as measured was on the order of .17 thousandths. Not exactly conducive to both safety and long case life.I purchased a couple #3 bolt heads from a friend "down under" And started checking the length of the locking lug on the right side of the bolt Till I found one longer in length than the one that came with the rifle. Unfortunately just screwing on the #3 bolt head wasn't that easy. It would not fully rotate to where I wanted it to be. I used a fine die makers stone and proceeded to remove a small amount of metal on the face of the bolt body. After about 5 tries
I had the bolt body and bolt head where they are supposed to be. The joint between the bolt body and the bolt head just showed a fine line. You want the bolt head to bear on the front of the bolt body and not on the threads. Checking the headspace it was now down to.004 thousandths. I plan on mounting a redfield international rear sight and a lyman series 20 front globe frong sight. Why the series 20 when I could have used the smaller series 17 lyman globe sight. Size of the inserts. The 20 series are much bigger and easier for older eyes to see through, mine are approaching their 63rd birthday. And I wanted the generaous windage and elevation adjustments that redfield gave their international series rear sights. And since I plan on shooting cast bullets with this rifle I'll need all the help I can get.
And soon will be glass bedding the back of the forestock, the draws, noxform, and where the barrel sits at the end of the forend.
So if anyone has any comments and or suggestions they will be most welcome. Regards, Frank

Sounds like an interesting project! I will look forward to your follow up postings. Sincerely. BruceV.

Quote:

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Originally Posted by Frank46

. Checking the headspace it was now down to.004 thousandths.

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Can you please confirm how you are checking the headspace - minimum headspace should be 0.064" and maximum should be 0.074"
How have you achieved a 0.004" headspace ?
Cartridge rim thicknesses vary by more than 4 thou so how will you accomodate thick rims ?

Look forward to your reply

"Confused of England"

I have a bunch of IVI unfired 303 cases, about 300 unfired "Hansen" cases, about 250 of the greek HXP cases and about 200 new winchester cases. I'll probably select one lot and put the micrometer in a stand and measure each case in 4 places write down the numbers and then do a bell curve graph to detirmine the ones I shouldn't be using. I used a piece of "plastigage" stuck on the base with crazy glue to get the .004 measurement. Whatever brand is selected then those cases will be used for that rifle only. That should help to weed out the oversized thick rims and also the thin ones. Used to do the samewhen I was taking up hi power shooting. I'll probably use one of the redfield international rear sights that I have. Has more windage adjustment than the olympic. I've already slugged the barrel and its measurement came out at .314, so add .002 you get .316. I see the need for a CBE mold around 200 grains in my future. As far as getting the .004 headspace that was fairly easy. I started out with a #3 bolt that measured @.636 then started checking the right side locking lug dimensions as far as length was concerned. Out of the four spare bolt bodies one was significantly longer than the others. I suspect wear will overtime reduce the .004 number slightly.
I've been shooting lee's for over 30 years. Jungle carbine, a #4MKII and the last which is a longbranch #4MKI*. The rifle has not been bubba'd by me. The bbl was cut to 22", parker hale sporting front sight ramp installed, all of the top wood taken off and the forestock shortened. The trigger has been lightened somewhat to about a 5 pound second stage. THat can and will be lowered somewhat lower. Have done this on a few lee's for friends and although its time consuming it does pay off. And yes I'm aware of the .064-.075 headspace thing. Its one of the reasons for the short case life. The oversized chamber also contributes to less than stellar case life. I have a buddy that tried many combinations of bolt heads and bolt bodies and essentially gave yup. So he made up a special bolt head that was longer than any available, then by using the go guage he trimmed the new bolt body till he got the headspace where he wanted it. Course he had the facilities of a fully equipped CNC machine shop to do in. I have had british MKVII cases get partial case head separations on their first firing. The glass bedding is necessary because the forestock as it is now on the rifle is very sloppy. Much movement of the forend especially where the barrel exits the forend. Hope that I have answered your questions and keep the comments and suggestions coming. One question though, what is supposed to be the standard for firing pin protrusion from the face of the bolt face? I used a depth micrometer and got.045. Thanks, Frank

Thanks - all clear now.
It was just an unusual way of describing headspace.

Anyway striker protrusion : Her follows an extract of notes from Peter Laidler :

"What you now need to end up with a correctly set-up bolt assembly is striker protrusion of between .040" and .050". This is measured when the cocking piece is in the fired position ....., that is fully forward! If the striker protrusion is above .050", then it is a simple matter of stoning it down, squarely, until it is just below .050". Once it is below and correct, with a square tip, then ROUND that tip to a radius of.038" (.076" diameter). Look, don't worry too much about this radius. As apprentices, we did it a million times until it was perfect. Suffice it to say, the tip shouldn't be SQUARE but neither should it be pointed! That's fairly obvious I hope.
Now, if it's BELOW .040", then it's time to shorten the bolt head tenon, the threaded part, against which the striker sits. This will allow the striker to protrude further through the face of the bolt head thus increasing the protrusion"

A simple way to fire form your cases and prevent stretching in the web area is to slide a small rubber o-ring around the loaded round and fire the round. I remove the extractor for this process for two reasons, one is to prevent the extractor from cutting the o-ring and the 2nd is the o-ring when compressed “centers the case at the rear of the chamber.

And rather than use plastic gauge a much simple method of getting your head gap clearance and your actual headspace measurement is the use a new unfired case and a fired primer.

NOTE: This same method can be used with a standard rimless case with the following thumb rule, the average case is two thousandths shorter than minimum headspace. Therefore you would subtract .002 from your seated primer mesurments.
(it works *trust me)

Click on the link below for how to on the .303

Checking Winchester Model 94 Headspace the Quick Way


* I have the means to check .308-243 cases before and after firing
https://www.milsurps.com/images/impo...IMGP5150-1.jpg

https://www.milsurps.com/images/impo...IMGP5163-1.jpg

https://www.milsurps.com/images/impo...IMGP5155-1.jpg

Alan, I'm kinda anal when setting up cases for each rifle that I shoot. The enfields being no exception. Guess old habits die hard. Uniform primer pockets and flash holes, measure each case and trim to shortest one in the lot. Thats one reason I get the lee cutter and lockstud case specific trimmer. If I have to trim I can always shorten the stem and mark it afterwards, they are cheap and they work. And measured the firing pin protrusion on the longbranch @.045. did some work on the interior of the bolt body, polished firing pin, polished firing pin spring and cleaned and polished the interior where the spring is inside the bolt body. May not do much but looks neat. The bolt body got cleaned up and polished, as well as the cocking piece and the lock screw. Methinks I have too much time on my hands. And the various selection of 303 brass was stored away long before the prices started going crazy. As far as getting a redfield international mounted, I have a sight base from a rem 513T that needs to be slimmed down in width so I can get the mechanical zero centered with the bore. Have to find someone with a surface grinder once I figure out how much has to come off. But if that fails on to plan B. I have a base setup that came off a L39A1 in 7.62nato. Has the same matchup that the paramount sight I have. don't have to drill any holes. Replace the ejector screw, remove military sight, another screw goes through the sight hole on the left side of the receiver and that's it.
Edward, I have a couple of the rcbs gizmos that you show. 308 and 30-06. Wish they's make them in 303.
And thanks to all who took the time and showed interest in this project. Now all I have to do is locate one of the "T" sniper cheek rests so's I can better see the sights. Frank