View Full Version : Measuring the bore

February 1, 2012, 08:23 PM
I bought these nifty 400 grain "Bone Crusher" bullets, really just to see what sort of things they would shoot through, and they are .458, but in the sabot they are .509 and I can't even drive them down the barrel with a short wooden dowel and a hammer. I got some Crushed Rib sabots for them and they still won't go. I'm sure there are easier ways to measure this bore than with this. http://www.brownells.com/.aspx/pid=22095/Product/INSIDE-DIAL-CALIPER I must be overlooking a simple way to do this.


There is an enlarged ball-seating-space of about 1/2 inch in the end of the barrel and so the jaws on my caliper won't reach down to the lands and grooves. Not that it will change whether or not the bullet fits, but I just won't order any more of that size.

February 1, 2012, 09:32 PM
yeah I'm gonna need to do the same thing with this GPR.

February 1, 2012, 09:47 PM
You can drive a lead slug part way down and then pull it back out and measure it.

February 1, 2012, 10:10 PM
There's a gunsmith's chamber casting alloy named CerroSafe (Brownell's sells it here (http://www.brownells.com/.aspx/pid=384/Product/CERROSAFE-reg-CHAMBER-CASTING-ALLOY)). Plug the bore with a wad hooked to a wire you can use to pull it out with, melt the CerroSafe (it melts at a temperature below boiling water), pour it in the barrel and let it cool, then pull it out. It shrinks in the first 30 minutes of cooling, then after an hour it returns to the exact dimensions it had in the barrel.

February 1, 2012, 10:17 PM
pour it in the barrel and let it cool

Weird, you know, I had the idea of plugging it with a cotton ball and pouring a little wax plug in there and pushing it out with the rod later. I was pretty close!

Ideal Tool
February 2, 2012, 02:12 AM
Hello, Beagle333..you probably wouldn't want to buy set for 1 use, but if you can locate machine shop, telescoping gage & micrometer would probably be safest bet.

February 2, 2012, 06:18 AM
Wax won't be accurate to three decimal places. CerroSafe is.

February 2, 2012, 01:12 PM
I have found the cerrosafe for $16.59 at Track of the Wolf.

February 2, 2012, 02:16 PM
MMP makes .50 caliber sabots that fit .458 bullets.
Perhaps they're thinner and have a smaller diameter than the TC Sabots.
I would ask MMP what the diameter is of their orange .458 sabots.

MMP also makes a Ballistic Bridge Sub-Base that may provide a benefit when firing such heavy saboted .458 bullets.
They can provide:

*Additional Gas Seal
*Cushion/protection of Sabot Base
*Improved Accuracy!


What rifle model do you have? :rolleyes:

February 2, 2012, 02:27 PM
That is the sabot that is supplied with it. MMP said they sell to T/C for this bullet. The guys at Harvester sent me some Crushed Rib sabot samples for a .452 bullet, and even though a tad shorter, they won't stuff in there either.
I guess it's true about the reviews that the Genesis was just a "cheap gun" and the bore sizes wander all over the place. Mine is pretty tight. But it shoots a prb really nice and it's a dream to clean. At any rate, this was just something to play with, I hunt with the .270, the .45-70, the 1894 or the 1895 anyway. I'll just use two patches, stuff these bullets in there and go see what they will do to different sized trees, and not buy any more sabots for this one.

February 2, 2012, 06:40 PM
Okay...... got the deal done with a .60 bullet, anyway, it's .502 on the lands and .514 in the grooves. The saboted bullet is .509 and that's why it won't go in there. At least now I know.