Posts: 8351 | Location: Jennings Louisiana, Arkansas by way of Alabama by way of South Carloina by way of County Antrim Irland by way of Lanarkshire Scotland. | Registered: 02 November 2001
OK here is the problem. I have a custom Encore barrel so there is no magazine to deal with as with a Winchester bolt gun. I was told it was tight necked and had a short throat. I took it that the throat was shorter than Winchester factory guns. Anyway I loaded some ammo starting 4 grans below max and went up 1/2 a grain at a time. Two grains from max I started to show black powder burns around the primmer. The load was for a Barns X 140 gr. ,because Barnes recomends 50 thousands back from riflings the bullet is deep into brass. I can have the throat lenthened to move the bullet out but because it is a custom barrel I have no factory recomended length. Still up in the air as to the bullet to use for hunting. Will be from Elk on down. I was in a local gun shop to day with my Stoney Point. bullet comparator and mic. I used a 300WSM split case and a 30 cal. 180 flat base bullet inserted backward to see what throat a NEW Browing A-Bolt was. It had almost no throat. I then measured a box of Winchester 180 gr. PPs .Using the 30 cal insert on comparator the 180s were 20 thousands longer than the chamber. Now I need to measure the Encore and compare the A-Bolt.
Take the pointy end of your 180 grain flat base bullet and insert it into the muzzle end of your barrel to mark the ogive. Seat this bullet so that it's base is flush with the base of the neck. With your caliper, measure the distance from the case mouth to the mark at the ogive and have your throat cut to this length.
There is usually .015 - .020 extra length in the neck portion of the chamber for which to grow brass, but you won't need to concern yourself with adding that to the measurement for the throat. Let that distance ride as a safety margin. You won't notice any difference by ignoring this .020.
A quick and dirty rule when a specific throat length isn't specified is usually 2/3 of the bullets diameter. In your case it would be .205, but you would be better off making up a dummy round with the bullet seated where you want it and having the throat cut to that length so that you don't end up with more throat than you can use.
If you were told you have a tight neck, it may be that you don't have enough clearance in the neck to release the bullet cleanly. If you haven't sized some of the fired cases that exhibited the primer leakage, try sliding a bullet into the neck of that case. If it doesn't slide in easily you will need to turn your necks. That may be causing excessive pressure. You should have a minimum of .002" clearance and in a hunting gun .005" would be better.
You can also loosely check the clearance by measuring the outside diameter of the neck of a fired case and then measure the diameter of the necks with seated bullets. The difference will approximate the clearance you have, if any.
Posts: 1261 | Location: Placerville, CA, US of A | Registered: 07 January 2001
Were getting a little side tracked. I was using the 180 because it was long and would work backwards ( flat base)to get freebore, about any 30 cal flat base would work. My thoughts for loading were some where in the 165 gr. range. If I were to use at least what Winchester used for throat I could use factory ammo if the need arised. I am finding that Winchester is short throated and is causing the large bullets to have fits. If they are makeing some chambers with throats shorter than Winchester ammo I see a desaster waiting to happen. Malm, I need to decide on a good all aroud bullet. Must be for Elk. The barrel maker recomended Barnes X 140 gr but I feel it is a little light. Also wheather to go boat tail or flat base. If I use Barnes they want 50 thousands freebore other wise I think 20 would be more than enough. Bob, all the brass I loaded is FL sized and necks turned. I had 2 thousands difference between the loaded bullet and fired brass.
I would use something heavier than the 140. Were it me, and I thought I might want to shoot some factory stuff through the barrel someday and I wanted it for Elk, I would probably choose something around 180 gr. minimum and throat the barrel for that.
