New 284 build. cases are not chambering question

[AKShooter]

Hello
I have a new 284 build. It's a 313 neck. Reamer was cut for Lapua 6.5 brass.

I took some brass. Expanded on a K&M 7mm expander. Then trimmed necks to .0135. Loaded round is at .309

The brass will not chamber. I actually took one piece and trimmed further into the shoulder. Way more than I would normally. This one does chamber.

So in my head, the neck shoulder junction needs to come back. I'm waiting on some neck bushings. I figured I'd full length size and go from there

Just figured I'd ask. Maybe someone had a similar issue

Thanks

 

[JamesnTN]

Sounds like the head space is a bit tight.

 

[noload]

Have you tried to chamber and 6.5X284 non expanded neck case just for the heck of it ?

 

[ShootDots]

Sounds like the head space is a bit tight.

I think James has this one nailed..

 

[AKShooter]

Was was to eager and expanded my entire lot...

I can get a go gauge on order. Would the only correction for too little headspace a trip back to the smith?

 

[338 Mollett]

James and Noload has given good advise!

 

[mr45man]

Try a feeler gauge under the case and size a few.
John H.

 

[tmwinds]

If you have a bump gauge and calipers measure one piece of brass and make note of the measurement. Use your full length sizer and bump the shoulder in .001 increments until the brass chambers with very slight resistance with the firing pin removed from the bolt. If you only have to bump a few thousands to get it to chamber you're good to go.

 

[PGS]

Maybe you need to trim the length of your brass. Could ask your riflesmith what the trim lenght is

 

[Rustystud]

My .284 has a .3175" chamber neck. My loaded cases are .3125". The old SAAMI spec for this round indicates .322" .
Just my two cents worth.
Nat Lambeth

 

[Erik Cortina]

Get a go gauge and if it chambers on your go gauge proceed by sizing your brass accordingly. However, I'm thinking it will not close on a go gauge. Keep us posted.

 

[Elwood]

Hello
I have a new 284 build. It's a 313 neck. Reamer was cut for Lapua 6.5 brass.

I took some brass. Expanded on a K&M 7mm expander. Then trimmed necks to .0135. Loaded round is at .309

I'm sure the others have got your diagnosis correct, but are you certain about those neck wall measurements?
All my 7mm's are .313 necks and to get a loaded neck diameter to 309 I have to turn the necks to 0125, if your measurements are correct your loaded round will be .311. The maths are .0135 x 2 + 284 = 311

 

[6mmcldasher]

If it's faster , just run it back to your smith , get him to run a go gauge in. take some brass with you.

 

[AKShooter]

Well, just an update. I went and picked up a Clymer go-gauge and a new batch of brass.

The bolt will not close on the go.........but, a brand new piece of 6.5x284 brass chambers just fine!! If I take the ones I just expanded and turned, and run them through my sizer and really bottom them out,,,,they will chamber.

So tight chamber, but it also appears I found an avenue to fire-form brass. Additional thought?

 

[JamesnTN]

It's your rifle but if it were mine I'd return it to the smith and have him correct the head space.

 

[Erik Cortina]

Well, just an update. I went and picked up a Clymer go-gauge and a new batch of brass.

The bolt will not close on the go.........but, a brand new piece of 6.5x284 brass chambers just fine!! If I take the ones I just expanded and turned, and run them through my sizer and really bottom them out,,,,they will chamber.

So tight chamber, but it also appears I found an avenue to fire-form brass. Additional thought?

This is your problem. It's called a Go-gauge for a reason.

 

[alf]

It seems the chamber is probably only a thou or two under the go gauge, as a virgin piece of brass chambers.

When he necks them up, part of the shoulder is now the neck, making it fatter there. When you use a bushing die, it doesn't touch this area either, you need a full length die to address that area.

When he turned a little further up the shoulder, it cuts off the hump, letting the brass chamber, same as bumping the hell out out the shoulder/neck area letting the bolt close.

 

[sparky123321]

As long as you're only going to shoot your own loads/reloads I wouldn't worry about it. You may want to grind a little off of the bottom of your FL sizer though so you can push the shoulder a little further back. I've had to do that before and its no major issue. I hate to send it back to the smith for a couple thousandths.

 

[Erik Cortina]

As long as you're only going to shoot your own loads/reloads I wouldn't worry about it. You may want to grind a little off of the bottom of your FL sizer though so you can push the shoulder a little further back. I've had to do that before and its no major issue. I hate to send it back to the smith for a couple thousandths.

If the smith can't ream a chamber to spec, I wonder what else he missed?

 

[AKShooter]

I was also wondering if there may be differences in the Go? Being cheap, the go I ordered was most likely 10-20 years old, used from ebay.

The chamber reamer was claimed to be for Lapua 6.5x284 brass,,,,,could this potentially be an issue not closing on the Go?

I heard folks running into issues with case, base width not using lapua brass in these chambers...