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Rounds won't chamber
Posted: Sun Jul 24, 2016 4:00 pm
by wildrover77
Just made up some new brass for my .338 whisper.
I have loaded 10 rounds but I cannot easily close the bolt on them.
Comparing to some of my existing ammo the only difference is the mouth of the case has a chamfer on the outside. The new brass has no chamfer.
The new brass chambers unloaded.
Do I need to chamfer the mouth of the new brass? Is the brass on the necks to thick?
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 4:25 pm
by phaedra1106
When you say "Just made up some new brass for my .338 whisper" what did you make them out of? If you're cutting down and forming from larger cases (30-06, 7mm BR or 308Win etc.) then the case necks are going to be very thick and would need to be neck turned.
If the cases chamber unloaded measure the neck diameter, seat a bullet and measure it again.
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 5:40 pm
by wildrover77
I expanded 6mm BR to .338. Surely that will reduce the thickness?
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 5:43 pm
by wildrover77
Camo paring a loaded round in the new brass to he old brass they look identical. I will get my calipers out and do as you suggest.
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 5:58 pm
by phaedra1106
I'm fairly certain that you'll have to neck turn those cases as there will be a small bulge at the base of the neck as part of the original shoulder will be used.
I'm assuming you've necked these up in 2 stages, 6mm to .30 then .30 to .338 and have annealed the necks?.
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 6:48 pm
by ovenpaa
Does unfired brass only chamber OK?
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 6:53 pm
by Rarms
Im guessing its a different profiled bullet which is hitting the lands.
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 7:10 pm
by wildrover77
I neck turned the brass, just to take of the donut after forming.
Yes expanded the neck in 2 stages.
The new brass chambers ok when not loaded.
I am using 300g bullets, which aren't a problem in the old brass which came with the gun.
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 7:17 pm
by ovenpaa
Fitting empty is not confirmation of all being well as once a bullet is in it may have expanded the neck far enough to just contact the chamber neck. I would be inclined to build a dummy .030" short and see if it chambers OK. Have you confirmed the OAL and trim to length?
Re: Rounds won't chamber
Posted: Sun Jul 24, 2016 7:36 pm
by wildrover77
Just measured 2 loaded rounds
The new brass with a bullet in place has a neck diameter of 9.33 mm while the old brass has a neck diameter of 9.16.
The new brass has a .4 mm longer neck.
Is this enough to stop chambering a round?