280 AI FT +P vs 7mm PRC

[VLD Pilot]

My 27" 280AI is doing 2950fps with 180VLDs and N560. Anymore than that is hard on the brass. I got lesser results with RL-23 which I had hoped to use. I think N550 might actually be better. Normal free bore I assume. Borrowed the reamer from a friend, but as far as I know he just ordered the standard 280AI reamer that PT&G stocks.

Why does everyone think they need a twist tighter than 8" in a 7mm? Berger recommends a 9" for the 180 and 195. Since Lapua took them over, Berger has reduced their twist recommendations, and in my opinion they went too far on a few bullets, BUT, they recommend a 9". An 8" is just fine. Run it through a calculator and you'll see.

Correct. Going down to an 8 actually will increase the BC number of the real long heavies. Brian Litz did studies and 8 maximized the BC. Anything faster or slower, the number dropped a bit. 8-9 is perfect for pretty much any bullet north of 150 grains.

 

[captacademy]

So I am have a Terminus Zeus switch barrel rifle built. So I don't have to change the bolt I went 22-250 AI fast twist, 308, and 280 AI fast twist with some free bore so I can load the bullets out and push the heavies. The 22-250 and 280 have 27" barrels. The 308 is 20". Tell me why I should consider a 7mm PRC over the 280 AI FT +P. The negative for me is brass and a $400+ bolt change. What does the 7 PRC give you the 280 in the above configuration won't? Just a curiosity at this point?

Factory ammo if needed.

 

[2Old2Care]

No clickers with 280AI

Just checked with two of my serious shooting friends and none of us know what 'clickers' are. Is it when a cartridge fails to feed and the firing pin goes 'click'?

 

[pointy sticks]

Click happens at primary extraction. Case web around the .200 line is tight.

 

[Wachsmann]

So is the 7PRC with the numbers hornady originally spec'd out was it with a 22 inch barrel or a 24 or 26. I see a lot of gun makers building them in a 22 inch which to me if it was spec'd in a 26 then that just totally defeats the purpose except for the faster twist barrel over the 7mm mag. Does anyone know?

 

[dogz]

Cans............

 

[Paladin300]

So is the 7PRC with the numbers hornady originally spec'd out was it with a 22 inch barrel or a 24 or 26. I see a lot of gun makers building them in a 22 inch which to me if it was spec'd in a 26 then that just totally defeats the purpose except for the faster twist barrel over the 7mm mag. Does anyone know?

That is a great question?

 

[dogz]

Cans............

meaning, so many people are going with cans and they generally go with shorter barrels when canning...

 

[Paladin300]

meaning, so many people are going with cans and they generally go with shorter barrels when canning...

The can is a mute point. If the data is for a 26" and you cut it to 22" you negate the need for a magnum cartridge because you lack the needed barrel length to burn the powder, thus the velocity gains over the 280 AI or a 284 would be minimal. You would be better served with the 280 AI in theory. Would you not??? Which is the point of this discussion. This coming from a guy who owns a 20" 300 win mag.

 

[dogz]

So is the 7PRC with the numbers hornady originally spec'd out was it with a 22 inch barrel or a 24 or 26. I see a lot of gun makers building them in a 22 inch which to me if it was spec'd in a 26 then that just totally defeats the purpose except for the faster twist barrel over the 7mm mag. Does anyone know?

He asked why...I answered my thoughts as to why...

 

[Wachsmann]

That is my thoughts. Some say the can acts like extra barrel length but I have no real world experience. I thought they are just to make it quite. I never shot a gun with a can so I have no experience on how quite they are or how the velocity changes but I did look on my Hornady phone app and they state a 24 inch barrel so maybe its spec'd with a 24 inch barrel. For me if I get one I want it in a 24 inch minimum probably looking more for a 26 inch barreled gun. This is also coming from someone that my main hunting gun is a Remington sendero in 300RUM. My 308 also runs a 26 inch barrel.

 

[dogz]

Totally get what you're saying, my 25/06 has a can on it and the barrel is 24" pre can. It's a long son of a gun, trying to work up the nerve to cut it but then I feel like I'm running a Roberts...

Most of the hard cores that know who shoot a ton load just deal with the speed loss to have the rifle balance a bit better.

I had my 70/7WSM threaded for a can and took the barrel from 23 to 22" don't think I'll miss the 25-30 fps loss at all. I'll tote it for spring bear more than a bit this spring.

It's all about choices I guess

 

[Wachsmann]

I don't even think I've ever been around someone at the range with a can.. Are they like Hollywood quiet, or just a lot quieter; and I've heard they don't scare game but any noise can scare game it seems. Bow hunting has taught me that. Just taping you bow against my tree stand spoked a doe from about 40 yards. She jumped and then ran about 30yards away and started stomping her front foot. It was a little funny to watch but I blew my morning hunt. (white tail.) Never smelt me just the single tick of the metal sound I guess was so different it scared her pretty good.

 

[Paladin300]

A standard caliber will loose about 25 fps for every inch you cut off. Most velocities are for a 24" barrel. Magnum calibers can loose as much as 50 fps and data for most of them is for a 26" barrel. 308 is tricky because the data can be for a 20" or 24". Cans do not necessarily add velocity. It is not the same as barrel length. I made the mistake of suggesting that one time, that is in correct. You do get back pressure which adds between 35-65 fps in velocity, so technically if you cut a couple inches off the lost in velocity is negligible, which was my point back then. If you cut more than that though you really aren't gaining anything by shooting the 7PRC over the 280AI or 284. A 20" 7 mag for example may loose 200 fps the 284 100 fps they both get the advantage of back pressure but with it you are only gaining maybe 100 fps and using 25-30 percent more powder in the 7 mag. If I were building a short barreled rifle for use with a can I would go 284 or 280 AI. It is just more efficient.