So I put in the Midway order for the poor boy's big bore-A&B Savage barrel, magnum bolthead, mag box etc. The only thing keeping this from being an at-home project is my lack of a fireformed round with which to set headspace. Are there 416 Taylor go gauges out there or tricks to setting up the barrel without one? Anyone want to sell a dummy round? I'd really like to get to the point where I could do this myself. Thanks again guys!

Standard belted go gauge. Same as used for all standard belted rounds other than 378-416-460 Weatherby & derrivitives.

Keep in mind there are many ways to set headspace on a belted round, depends on several variables: Thickness of the belts (this can be brass maker specific, for example 0.208-.210 for Rem, 0.214-.215 for Win, ect, these are averages), what the rifle is used for (hunting, tactical, long range precision shooting, etc.). The go gauge thickness is 0.220. Generally you would be OK to set the headspace so the bolt closes with resistance on the gauge on a hunting rifle. However, with some cases that have thin belts (like the.208 Remington) you will have excessive headspace if you set so the bolt will close on a Go gauge.

Confusing, huh??? Note the numbers, this is why belted brass has a reputation for head separations after a few firings. Chamber snugly on the belt, and separations are a thing of the past. BUT!!! This is dangerous for a big bore hunting rifle, you can and will have cartridges that will not chamber. Not nice when you are using a custom tight chambered 375 H&H, lose your ammo, and have to scrounge whatever is found in a far distant gun shop.

What is important for a hunting rifle is that all cartridges will chamber and the bolt will fully close.

I will post a photo in a bit showing a gauge used to measure belt thickness.

[ 03-02-2003, 09:40: Message edited by: John Ricks ]

Here is the belt gauge. Dial indicator is zeroed on the top of steel cylinder gauge, which is bored to take H&H based cases, and the belt stops on the top of the cylinder. Insert a case, pull up the indicator plunger, slide the gauge with case under the plunger, and read the thickness on the dial.

Measuring and sorting belts is important on match rifle chambers where we headspace about 0.001" over belt thickness.

Yep, that Starret dial indicator says 0.208" for belt thickness on new unfired 416 Rem brass made by Remington. So, if your chamber closes on a go gauge, you automatically have at least 0.012" excessive headspace, maybe more.

NOW one sees the desire for non belted cases. One less variable to contend with.

However, I still trust a correctly chambered 458 Lott DGR.

[ 03-02-2003, 09:38: Message edited by: John Ricks ]

John Ricks,
Great information and well put! You answered a couple of questions I had as well. Thanks!
best,
bhtr

Yep, I had a lot of questions back when I chambered my first barrel (a 338 Win) concerning belts and headspace. Seems everybody has a different opinion.

I have sort of formulated my own rules for chambering belted cartridges: First, you gotta find out just what the rifle will be used for and how proficient the owner is in the art of handloading.

Then determing what bullets will be mostly used. If it is a long range precision rifle, with carefully crafted handloads, we may get into tight chambers, close throats, shallow throat angles and snug fitting belts. Still gotta have a dose of caution here, as we can be treading on pressure problems.

Rules are different with a hunting rifle that must chamber any and all brands of cartridges, various bullets, and sometimes be subject to fast reloading.

For example, I have 5 different reamers for 300 Win Mag alone, for hunting chambers to extremely tight base and tight neck match rifle chambers. Some of the reamers are throated for a specific bullet.

I used to dabble in benchrest and 1000 yard rifles. Learned some interesting things, but my first love is big bore hunting rifles.

I will take a couple of photos next week when chambering a barrel, showing how to use a dial indicator to figure out just how much headspace you have in the chamber. Dial indicators can tell you a lot, it would behoove those chambeing barrels to obtain several good indicators and learn how to use them. I will post the photos, as each one is worth 1000 words.

[ 03-02-2003, 20:15: Message edited by: John Ricks ]

John--
Fantastic information, thank you. I look forward to the pictures--you might post them to another thread so that others not interested in my specific project will still pull them up. I look forward to putting your ideas into practice.

I run across a similar problem with my A&B 416T barrel. I used Rem 416 brass to make some cases and headspaced snugly and checked with several cases to be sure. When I tried to chamber a necked down 458 Win it wouldn't go into battery. I pulled out my belted mag gauge and it measured 0.222". So, just for kicks and edification I used the gauge to headspace on, set the action/barrel square, unscrewed the nut and re-headspaced on the Rem case. I had to screw the barrel in almost exactly one quarter turn for the Rem case and a tad less for the Win case. That equals at least 0.012", one quarter turn for 20 tpi. Makes you think doesn't it? Wonder what my 7mmMag brass measures?