Having to bump shoulders back on new Lapua brass to chamber??

[Tsu45]

Would this concern you about the chamber being too short? I’m having to bump the shoulder back on virgin 6.5creed Lapua brass .004-.005 to get no resistance on bolt close. Getting the resistance on factory ammo as well.

Just though I’d ask before resizing 400 pieces since I haven’t encountered this before. Safe to just bump the shoulder and continue with load development? Should I not fire the factory ammo?

Barrel is new

 

[JohnKielly]

Don't bother. Chances are that the diameter of your chamber is wider than the brass so when it fires first time it may well change dimensions.

Apart from that, you have the optimum relationship between case & chamber to ensure it will perfectly fire form to chamber dimensions without expansion & thinning at the base.

 

[Tsu45]

I usually run it through to straighten it up anyways, so it isn’t really a bother. I was more concerned with the safety aspect, but sounds like that is good. Factory ammo ok to shoot if I grease the lugs?

 

[MikeMcCasland]

If you're getting stiff bolt closure on both factory ammo, and new brass, that doesn't seem right to me. Typically new brass, and especially factory ammo is well undersized, so that's a bit concerning. Hard to say if that's a safety issue though; probably not, but it shouldn't be "tough" to chamber it.

Who installed the barrel? Is this a barrel-nut type system?

 

[Tsu45]

If you're getting stiff bolt closure on both factory ammo, and new brass, that doesn't seem right to me. Typically new brass, and especially factory ammo is well undersized, so that's a bit concerning. Hard to say if that's a safety issue though; probably not, but it shouldn't be "tough" to chamber it.

Who installed the barrel? Is this a barrel-nut type system?

It’s a shouldered prefit on a Nucleus that I installed at 40ft/lbs.

 

[jepp2]

Safe to just bump the shoulder and continue with load development?

I assume you have the ability to measure case head to datum, right?

How does your brass (Lapua and factory) compare with the headspace gages?

 

[Tsu45]

I assume you have the ability to measure case head to datum, right?

How does your brass (Lapua and factory) compare with the headspace gages?

Don’t have headspace gauges, but if I’m tight on both we know it is short.

 

[jepp2]

Don’t have headspace gauges, but if I’m tight on both we know it is short.

Just compare with SAAMI specs:

Cartridge: 1.5438 - 0.007
Chamber: 1.541 min, 1.551 max

Why is there never time to do it right, but always time to do it again.... Measure and know instead of assume.

 

[MikeMcCasland]

I strongly doubt it's a safety issue, but it shouldn't be tight on both unless you had it cut that way with a specific reamer. As John pointed out, it might be better for your brass life, but it doesn't seem right on a pre-fit.

I will also say that the only time I've ever played with intentionally heaspacing a barrel too tight, I ran into problems with stiff bolt lift/extraction.

 

[Tsu45]

Just compare with SAAMI specs:

Cartridge: 1.5438 - 0.007
Chamber: 1.541 min, 1.551 max

Why is there never time to do it right, but always time to do it again.... Measure and know instead of assume.

I guess I’m not sure what conclusions I could draw from that exercise that I don’t already know, or how I would reconcile a Hornady headspace kit measurement to the saami measurement. There is resistance chambering two factory loads and virgin brass. The chamber is undoubtedly slightly short.

Knowing that I only have to bump it .004 to get zero resistance, are there any drawbacks to doing that for the first firing?

 

[Tsu45]

I strongly doubt it's a safety issue, but it shouldn't be tight on both unless you had it cut that way with a specific reamer. As John pointed out, it might be better for your brass life, but it doesn't seem right on a pre-fit.

I will also say that the only time I've ever played with intentionally heaspacing a barrel too tight, I ran into problems with stiff bolt lift/extraction.

Thanks, Mike. Pending what the shop says I might just do 100 pieces to start.

 

[Zero333]

One other thing you may check is to paint a virgin piece of brass with a marker and chamber it.

This might show weather the chamber is short or just tight.

Personally I wouldn't care as long as it chamber's. But that's me.

Did you clean the barrel and chamber throughly ?
There might be a burr left over somewhere as well.

 

[Dusty Stevens]

All new brass should be fl sized as the first step out of the box

 

[KMart]

It’s a shouldered prefit on a Nucleus that I installed at 40ft/lbs.

Somebody correct me if I am wrong here.
Aren't shouldered prefit barrels purposely chambered SHORT? Then the headspace is corrected by using go/no go gauges and a reamer?
Or adjusting the headspace by using a slightly thicker recoil lug, again using go/no go gauges to confirm the fit.

 

[dolek]

Somebody correct me if I am wrong here.
Aren't shouldered prefit barrels purposely chambered SHORT? Then the headspace is corrected by using go/no go gauges and a reamer?
Or adjusting the headspace by using a slightly thicker recoil lug, again using go/no go gauges to confirm the fit.

That was my thought also . I have only done a few shouldered pre-fits and they all came short-chambered .

 

[Richard Coody]

I guess I’m not sure what conclusions I could draw from that exercise that I don’t already know, or how I would reconcile a Hornady headspace kit measurement to the saami measurement. There is resistance chambering two factory loads and virgin brass. The chamber is undoubtedly slightly short.

Knowing that I only have to bump it .004 to get zero resistance, are there any drawbacks to doing that for the first firing?

i would get a go gauge and check it. we pretty much know what the answer is but it would be nice to confirm it.

well if after bumping the shoulder back and getting no resistance we know the chamber body is not tight. The chamber is just short. new lapua brass is already short and if you are having to bump new brass .004 just to get it to chamber that chamber is quite short.

you have to decide if that is acceptable or you need someone with a finishing reamer to lengthen that chamber slightly.

if all you plan to shoot are reloads then it really shouldn't be a problem to leave it as it is. overall length of your brass will always be short. your necks will be a little longer to start so trim length will change. with a trimmer that indexes off the shoulder that shouldn't be a problem difficult to fix. That brass will be only for that rifle.

fireformed dimensions should answer a lot of questions. Remember it may take 3 firings to be fully fireformed. check dimensions after firing and when they stabilize you know the brass is fully formed.

 

[dolek]

All new brass should be fl sized as the first step out of the box

Why ? Are you saying quality like Lapua brass is not sized properly ? I make sure my necks are round,but never FL size new brass . I have tried it both ways,IME FL is a waste of time . What am I missing,always willing to learn .

 

[Richard Coody]

Why ? Are you saying quality like Lapua brass is not sized properly ? I make sure my necks are round,but never FL size new brass . I have tried it both ways,IME FL is a waste of time . What am I missing,always willing to learn .

opinions vary

whatever works for you

i run an expander mandrel through the necks and load and shoot.

don't do any trimming or neck turning or or setting up sizing dies until that brass is firefirmed. now if you have a tight necked chamber or did some radical case forming you might want to go ahead and neck turn.

 

[dcali]

I never size new brass, and it has always fit. I agreee that you should measure your chamber, as it’s likely small. Not tragically small, but out of spec. That may not do anything bad. If factory ammo is sticking, you’re just asking for headaches.

 

[carlsbad]

Since your chamber is shorter than spec for 6.5 Creedmoor, you should rename it.

1. It may catch on and be the next hot thing.
2. You can deflect all the creedmoor comments as not-applicable to you.