Tight Bore Barrel

[gsg5pk]

Tight Bore Seat Depth



I just received 2 rifles from local gunsmith. Both were build on Stiller Tac 30.

• Bartlein Barrel 5R HV 1:10 tw (.300/.308 Bore)

• Bartlein Barrel 5R M24 1:11.25 tw (.299/.308 Bore)


Both barrel were chamber with the same reamer PTG F-TR .342"nk , .168 fb with 1-30

The suffer problem that I got from different in bore diameter was their Seat Depth to touch the land.


(.300/.308 Bore)
168 SMK
COAL = 2.900" , CBTO = 2.325"
175 SMK
COAL = 2.910" , CBTO = 2.325"
175 LRBT
COAL = 2.990" , CBTO = 2.329"


(.299/.308 Bore)
168 SMK
COAL = 2.770" , CBTO = 2.200"
175 SMK
COAL = 2.780" , CBTO = 2.210"
175 LRBT
COAL = 2.890" , CBTO = 2.226


Do you have an experienced of different in bore diameter?

The smaller of .001" bore will affect these huge number of Seat Depth around .100"?



Best Regards,
GSG

 

[LC Tikka]

Hi GSG
Firstly the bore dia is the minor figure, groove dia the major/.308.
I could be wrong but I doubt if bullets when touching the lands are making contact on the inner edge but somewhere on the taper of the land. 1 thou would make no real difference, if it did all the free-bore figures quoted for reamers would never match the spec as there are some variations in bore & groove dia between barrels and makes.
If the same reamer pilot was used for both barrels then there would likely be a slight difference in chamber diameters due to the looser fit.
Why you measure 100 thou seating variation is not due to the 1 thou difference in the barrels IMO.
LC

 

[gsg5pk]

Thus make me suffer with those outcome.



I had order throat reamer from PTG and plan to throat it out.

With throating reamer, do I need to remove barrel out of action before throating?

 

[338 Mollett]

I would,for being able to clean the shavings better alone.

 

[aj300mag]

The bullet doesn't touch the minor diameter. If he used the same reamer something else is wrong.