SAMMI 280 ACKLEY IMPROVED CHAMBER LENGTH QUESTION

[Roughrice]

Can you not face the breech on the Remage barrel and bring it sync with your other rifle?

That sounds like what I need to do as I think it would be great to at least size the brass the same if they are within 1 or 2 thousanths.

This^^^
Have you tried to shoot standard 280rem out of that chamber? If it's not a tight bolt close on standard 280rem then the chamber is cut long/wrong.

I do have some 280 Rem ammo.
I did not fire any but I did close the bolt on both rifles and felt very little if any resistance.
I even used a crayon to color the shoulder and I saw a touch on both but no tightness felt.
Weird thing is when I measure fired Nosler 280 AI brass from both chambers... I have 5-6 thousanths difference in case length to the .375 Datum line.

 

[Pdvdh]

According to this article, there is no difference. It sounds like the Remage has excessive headspace. I would think that you could have the breech face machined to "tighten" up the headspace at the same time giving you more clearance between the breech and bolt face.

280 Ackley headspace comparison

Disclaimer: I am an armchair gunsmith, take this with a tablespoon of salt and talk with your gunsmith.

The author of that article got it wrong. As have a number of others. The link below demonstrates this, using basic arithmetic. Addition and subtraction.

The difference in headspace between the two is ~0.014". Doesn't solve the OPs issue.

280 Ackley Chamber

Reamers and gauges are made following those SAAMI prints. If your reamer doesn't conform to SAAMI specs, its the reamer or gauge or both that is wrong, not the print! And, for what it's worth, .280 Rem brass or factory loaded cartridges won't "crush fit" into any SAAMI .280AI chamber I have had...

www.longrangehunting.com

 

[DUCKMAN11]

That sounds like what I need to do as I think it would be great to at least size the brass the same if they are within 1 or 2 thousanths.

I do have some 280 Rem ammo.
I did not fire any but I did close the bolt on both rifles and felt very little if any resistance.
I even used a crayon to color the shoulder and I saw a touch on both but no tightness felt.
Weird thing is when I measure fired Nosler 280 AI brass from both chambers... I have 5-6 thousanths difference in case length to the .375 Datum line.

Put a peice of scotch tape over the base/head of the case and try to chamber the standard 280rem. If the bolt still closes easily then your chamber is cut long. A standard 280rem should be a crush fit in a 280ai chamber.

 

[DUCKMAN11]

If you have 2 barrels with the same tenon and thread dimensions....cut with the same reamer...to the same depths...with the same action screwed onto the identical barrels then and only then could your headspace be the same. I'm not 100% sure that the .375" datum line is where you should measure from on a 40° shoulder but that wouldn't really make a difference at this point. 6 thou is a big gap nonetheless.

 

[Roughrice]

Put a peice of scotch tape over the base/head of the case and try to chamber the standard 280rem. If the bolt still closes easily then your chamber is cut long. A standard 280rem should be a crush fit in a 280ai chamber.

I can barely feel the 280Rem with scotch tape on one rifle.
The Remage barrel is cut too deep.
I don't feel resistance with the 280 with scotch tape.
When I try to tighten headspace it bottoms out on lugs.
May have to have the breech face cut back a bit.

 

[26Reload]

So to speak....
Every cut with a reamer can be different...the reamer isn't exactly perfect..just close..so specs do change...

 

[Roughrice]

So to speak....
Every cut with a reamer can be different...the reamer isn't exactly perfect..just close..so specs do change...

Understood.
These were not cut by the same Smith and definitely not the same reamer.

 

[DUCKMAN11]

I can barely feel the 280Rem with scotch tape on one rifle.
The Remage barrel is cut too deep.
I don't feel resistance with the 280 with scotch tape.
When I try to tighten headspace it bottoms out on lugs.
May have to have the breech face cut back a bit.

Load up a dummy round of fired and unsized ammo from your other 280ai and ask the Smith to "cut it for this round".

 

[DUCKMAN11]

Good luck!

 

[Roughrice]

Thank you guys for your input on the matter!
I hope to get this small issue resolved mostly for convenience for the sake of at least resizing for both with the same die setting and not have to keep everything separate.

 

[59FLH]

The author of that article got it wrong. As have a number of others. The link below demonstrates this, using basic arithmetic. Addition and subtraction.

The difference in headspace between the two is ~0.014". Doesn't solve the OPs issue.

280 Ackley Chamber

Reamers and gauges are made following those SAAMI prints. If your reamer doesn't conform to SAAMI specs, its the reamer or gauge or both that is wrong, not the print! And, for what it's worth, .280 Rem brass or factory loaded cartridges won't "crush fit" into any SAAMI .280AI chamber I have had...

www.longrangehunting.com

It appears as though you did not take into account the difference in the radius at the neck shoulder junction between 280 REM and 280AI. The larger radius on the 280 REM contributes to the "crush"

 

[59FLH]

To the OP

My guess is one chamber is close or at SAAMI minimum and the other is at the middle of the tolerance (+.005")

I would do as suggested and face the breech end of the barrel for additional set back but use a head space gauge not a case.

Did you confirm the interference is the bolt lugs and not the nose?

 

[L.Sherm]

The radius on the 280 Rem and 280AI saami are the same at the neck shoulder junction the crush on the 280AI comes from the boltface to the neck shoulder junction being shorter on the 280AI than the standard 280 Rem.

 

[59FLH]

I could be wrong but according to the SAAMI prints he posted, to me it appeared the 280 Rem rad is .125" and the AI is .06".