Need some advice on bolt rifle build

[swd]

swd, are you shooting a .175" freebore with your 109s?

My BRX reamer has .140” and if 109’s were the only bullet I planned on shooting .175” would be about perfect.

 

[707electrician]

I ended up cutting a window in a piece of brass and seating a bullet so the base of the bullet is right about where the body-shoulder junction is and this puts about .145" of bearing surface in the neck. I loaded up three more dummy rounds to the same length and I think this is what I will have my reamer cut to. It looks like the freebore is going to be around .220".

Any other words of advice, or should i send it?

 

[whatsupdoc]

Dont send it, I dont shoot Dasher but .220 does not seem correct.

 

[Dusty Stevens]

Not sure how you measured that to ..220 thats more like a .130fb judging by how it looks and the ones ive done itll be perfect

 

[707electrician]

The 109 hybrids have a .431" bearing surface, so with .145" of that in the neck, that is .286" of bearing surface extending out of the case so the freebore may be longer than .220" unless I am missing something.

 

[Dusty Stevens]

The 109 hybrids have a .431" bearing surface, so with .145" of that in the neck, that is .286" of bearing surface extending out of the case so the freebore may be longer than .220" unless I am missing something.

Thats not how it works although you may be correct on your measurements. Do a search on here for measuring freebore. Theres a pretty fresh topic in the main forum. What i suggest is to get that pressure ring seated halfway in the neck and send that to your gunsmith and let him do what he does. Theres no way for you to measure or calculate freebore unless you have an optical comparitor and know exactly what to measure. After doing dashers and every other 6mm cartridge out there using bullets even longer than that for many years, a .150fb reamer will even most likely be too long

 

[Stan Taylor]

Thats not how it works although you may be correct on your measurements. Do a search on here for measuring freebore. Theres a pretty fresh topic in the main forum. What i suggest is to get that pressure ring seated halfway in the neck and send that to your gunsmith and let him do what he does. Theres no way for you to measure or calculate freebore unless you have an optical comparitor and know exactly what to measure. After doing dashers and every other 6mm cartridge out there using bullets even longer than that for many years, a .150fb reamer will even most likely be too long

You are right Dusty ,I’ve seen a lot of the .155 free bore Reamers on the market for sale a lot of these custom bullets you don’t need any more than .120. Lead

 

[707electrician]

Thats not how it works although you may be correct on your measurements. Do a search on here for measuring freebore. Theres a pretty fresh topic in the main forum. What i suggest is to get that pressure ring seated halfway in the neck and send that to your gunsmith and let him do what he does. Theres no way for you to measure or calculate freebore unless you have an optical comparitor and know exactly what to measure. After doing dashers and every other 6mm cartridge out there using bullets even longer than that for many years, a .150fb reamer will even most likely be too long

I have been reading that thread you are referring to, and maybe I am not understanding freebore completely.

I guess my question really is; do my dummy rounds look good? My intention is to send these off to JGS to have a reamer made so I will let them figure out what the freebore really is.

 

[One Eye Pete]

I only shoot two bullet diameters 6mm and 7mm. For both of these diameters I purchased a PTG unithroater. When I purchase a new reamer I generally specify a freebore that is on the short side. With the unithroater I can always add freebore but if your reamer comes with too much freebore and you chamber your barrel with it you can't reduce the freebore. Most of the rifles I shoot shoot best somewhere between .020 jam and .030 jump. The unithroater allows me to get my chosen bullet just about right where I want it sitting in the case neck.
The only thing with a unithroater is that it can cut metal really fast. When you use one I can't overemphasize go very slow, take very little metal at a time and you can get the bullet right where you want it.
The way you have the bullets sitting into the cases looks OK to me. I like to have the boattail bearing surface junction on the bullet just above the neck shoulder junction on the case.