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Crazymonkey

7-08 shooting faster than it should?

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The .280AI will push a 140 @ 3200+.  Or a 175 @ 2900+ easily.  7-08 won't match that.

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I've loaded quite a bit for 7mm08.  Reloder 17 always gave me more speed than I expected.  I moved away from it because 1) I didn't like compressing the powder that much, and 2) I saw very noticeable changes in velocity when I shot in hot weather. 

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12 hours ago, lancetkenyon said:

The .280AI will push a 140 @ 3200+.  Or a 175 @ 2900+ easily.  7-08 won't match that.

We talked about my goals for the 280 build and twist rates .I'm still going to build it and will be ordering the proof barrel and trigger in July after my hunt in June.As for prdatars question on twist .I'll have to check as I don't remember off the top of my head.But Keith and I had a conversation about what I'd be shooting and I didn't want to go above the 140's so it was built to run the lighter stuff.The case volume in the Ackley will let me run 168's and 175's with a 9 twist no problem and the brass life will be better I've heard.

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7 hours ago, Crazymonkey said:

We talked about my goals for the 280 build and twist rates .I'm still going to build it and will be ordering the proof barrel and trigger in July after my hunt in June.As for prdatars question on twist .I'll have to check as I don't remember off the top of my head.But Keith and I had a conversation about what I'd be shooting and I didn't want to go above the 140's so it was built to run the lighter stuff.The case volume in the Ackley will let me run 168's and 175's with a 9 twist no problem and the brass life will be better I've heard.

A 9 twist better on brass? I've been shooting the 280A! since 1990. Always shot 165-170 weight bullets with 8 or 8.5 twist. Todays bullets are even longer and require 8-9 twist with 9 twist on the marginal side for best accuracy. I'm helping a friend put one together right and it'll be an 8 twist Brux on a Kelbly Atlas action. My advice to him was to buy Lapua 30/06 brass and neck down. 

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16 minutes ago, L Cazador said:

A 9 twist better on brass? I've been shooting the 280A! since 1990. Always shot 165-170 weight bullets with 8 or 8.5 twist. Todays bullets are even longer and require 8-9 twist with 9 twist on the marginal side for best accuracy. I'm helping a friend put one together right and it'll be an 8 twist Brux on a Kelbly Atlas action. My advice to him was to buy Lapua 30/06 brass and neck down. 

I'm still learning this stuff the barrel will have little effect on brass life but the 40 degree shoulder helps with case stretch and powder volume.Something to do with the angle helping to prevent brass flow there for increasing brass life.

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My .280AI has a 1:9" twist.  It shoots the 175 Elites amazingly well.  Also a 160TMK is deadly accurate and fast.  But a mono would be limited to the 145LRX or 154 Absolute Deadblow Hammer.

If you plan on shooting monos, a 1:8.5" will shoot up to the 168LRX or 169 Hammer Hunter.  It will also shoot up to a 184 Berger Hyb.

If you want to maximize for true heavies, a 1:8" will spin a 195 EOL or a 177 Hammer Hunter.  

My opinion, a .280AI does best with a 160-180.  If you want to shoot heavier, might as well step up in case capacity.

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On 5/16/2022 at 2:59 PM, Crazymonkey said:

I was out this weekend and finally got to Cronograph my 7-08 and its shooting above barnes velocity .Here are the gun and load specs.

Custom 7-08 brux #5 26inch barrel work by Phoenix custom rifles.

Lapua brass trimmed to spec

140 gr ttsx barnes

45.6 gr r17 middle of the recommended charge weight per barnes

Federal mag primer

Coal is 2.755

2.165 to the olgive

Bullet seated .05 from the lands as checked with a Hornady gauge.

Labradar has me at 3026 low and 3042 high .

I'm not getting any pressure signs but barnes has 47.8 gr r17 as a high and 2910 for velocity.I'm no where near max but above the speed .The gun groups outstanding if I do my part but that seems way fast given the charge weight.Anything to worry about or run it up the ladder and see what it gives me for max?Accuracy always trumps speed but this seems fast .

I have literally never hit pressure signs from the recommended max.   I expect to hit 100-200fps more speed than recommended max.   Now I don't drive them that fast but the velocity is there if you are a speed demon.   I watch my brass and let my gun tell me what is going on.   It's great you are tracking speed.   If the barrel is new then doing load development for accuracy is not awesome until you get constant speeds.   I've found that a new barrel will take 50-100 round to calm down and become consistent.    A new barrel will just get faster and faster as you shoot pills down the tube.   So, until the barrel gets broken in your speeds will change and that will cause you accuracy issues.   

If you find a speed that is accurate make sure to remember it.   The load isn't the key it is the speed of the bullet that is the key and as your barrel breaks in you will be able to use less powder to get the same speed.  Sounds like you are in for loads of fun!!!!!!!      

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On 5/16/2022 at 4:38 PM, PRDATR said:

Why are you using Magnum Primers?

Primers are just another variable to play with. I often try standard primers in my large capacity case (e.g. 300 Weatherby), and Mag primers in small capacity cases. Just a tool to fine tune. 

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