Long throated 280 Ackley question

[KyleC]

I bought my 280 Ackley second hand and it had a SAAMi chamber so I sent it to Gordy Gritters and had him add .200" freebore. I can seat them long and still fit in the BDL. So my question is, approximately how much powder will I be able to add? I've already am at max Nosler book with Reloder 23 and N560 with pretty good accuracy but speeds were pretty slow. The barrel is a 24" 1-8 Bartlein and I'm using Peterson brass (all fireformed to my chamber).


Peterson Brass (all fireformed now)

 

[cajun]

In your case the long freebore is lowering pressure and the velocity. The grains of powder is not as important as the max velocity listed. In some cases it may take less to get there. It's just a guide. I would creep up watching the chrono and keeping an eye out for pressure signs.

 

[adk hunter]

I've seen two thing personally happen with what you are trying.

One is a fast barrel vs a slow one can impact velocity as much as a small gain freeborn gives. The second is some guys have greater tolerance for hot loads with heavies. Not my idea of best practices.

7mm, heavies and speed say 7 Rem Mag, 7PRC and .28 Nosler to me.
My .280AI's live in the 160 class bonded or 130-150 class monos.

You are just going to have to try what your rifle wants. It will tell you better than guessing.
Good luck! My .280AI's are saving me thousands from wanting a ride on the 7 PRC train LOL

 

[Tiny Tim]

Agree with @cajun. Slowly increase powder charge and watch your chronograph and target. I've found that starting at the lands and increasing seating depth will lower velocity (& pressure) for a while, then it will stabilize until you get too far into the case.

 

[Dmagna]

I have a custom throated 280 ai for the 175 eldx. I can put a lot of powder in there, I went up to almost 60 grains of rl23 before I hit any pressure.

Running a 175 eldx at 2900 from a 24" barrel

 

[Mark37082]

I've thought about adding free bore to my SAAMI 280AI. The primary reason was running into the powder crunch when seating long monos (ie., 150 BD II's) when using extruded powders. Tried StaBall 6.5 and achieved good velocity but it pressure spiked very quickly. I too have settled on mono's in the 140 range (currently HH143) or 160 gr AB's. This seems to be the sweet spot for my rifle.

 

[Roughrice]

I agree with previous posts.
Hard to give an opinion without knowing which bullet you plan on using...but, I'll assume you throated it to shoot longer monos.

I don't shoot copper monos but my SAMMI chambered freebore allows enough room in the case for 58.5 grains of RL 23 and 60 grains of N560 with 168 ABLR with very good accuracy and speed.

 

[KyleC]

Sorry I did not mention the bullet......160 Accubond

 

[Roughrice]

Gotcha!
Those powders should work well with that bullet.
Don't know how much your jump will be but in my experience Ballistic Tip don't mind a long jump (up to 150k) and Accubond is just a tad more sensitive to seating depth.
With that said…Even though your freebore sounds a bit long, You should find a happy place with Accubonds even if you have to jump them some.

My 284 Wins are long throated and jump the Nosler 150's (ABLR, Ballistic Tip) a long way and shoot very well!

Sorry I couldn't give more on charge weights with longer freebore.