Rounds won't chamber

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#1 Post by **wildrover77** » Sun Jul 24, 2016 4:00 pm

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?

#2 Post by **phaedra1106** » Sun Jul 24, 2016 4:25 pm

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.

#3 Post by **wildrover77** » Sun Jul 24, 2016 5:40 pm

I expanded 6mm BR to .338. Surely that will reduce the thickness?

#4 Post by **wildrover77** » Sun Jul 24, 2016 5:43 pm

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.

#5 Post by **phaedra1106** » Sun Jul 24, 2016 5:58 pm

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?.

#6 Post by **ovenpaa** » Sun Jul 24, 2016 6:48 pm

Does unfired brass only chamber OK?

#7 Post by **Rarms** » Sun Jul 24, 2016 6:53 pm

Im guessing its a different profiled bullet which is hitting the lands.

#8 Post by **wildrover77** » Sun Jul 24, 2016 7:10 pm

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.

#9 Post by **ovenpaa** » Sun Jul 24, 2016 7:17 pm

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?

#10 Post by **wildrover77** » Sun Jul 24, 2016 7:36 pm

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?

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