.270 AI owners sound off ...

[Don A Parsons]

One would think that H1000 and Short Cut H4831 would be nice powders to work with as well,,, the bullets might not be as fast in ft-per seconds as using the R powders...

At least there are options out there for us in what might be available in our areas threw out the Americas.

The .277 idea crossed my mind before I picked a different caliber on my build,,, a benefit I see is opening up the bore more than the 65's,,, a chance to gain a few more ft-per seconds and a verity of more bullets in the 270 category to choose from...

Maybe the 270AI is the new up coming Moorcreed...

Let's not forget that .277 is the closest thing to the real 7mm,,, if I recall it's actually 7.03mm... LOL

Another benefit is the 130gr rifle land to barring surface,,, way less chances of the bullet corking down the pipe,,, one would think that even the shorter bullets in the 117 and 120gr would pilot down the pipe straight...

This is one of the reasons I don't prefer to shoot 147gr 308 bullets,,, just not enough barring surface along the flat sides to keep it alined and straight traveling down the pipe,,, noting worse than ending up with wobble right of the bat... Ha

Just me i guess,,, to much old school thinking from the old timers...

Beautifully morning sitting in my toasty warm blind with Elk in the midst,,, I just hope one shows up for breakfast... Ha

 

[Frog4aday]

I think there might be some diminished BC due to the slower twist. but only testing will tell. https://www.rokslide.com/forums/threads/berger-170gr-eol-vs-matrix-165gr-vld-plus-freebies.43228/

I read the three pages of thread. Sadly, the OP who was shooting the 170gr Bergers didn't say in TEXT what he was getting for accuracy, he just posted pictures and all the 'markers' for the pictures say "picture not found" so I didn't get much out of it. Some other member shot the bullets in 1:9" twist and got good accuracy from a .270WSM.

Now I'm curious. Seems at max load, the OP was (apparently) getting good results from a 24" long .270Win barrel with a 1:10" twist. If true, a guy could just rechamber and go with the barrel they have now. Tempting.

 

[Michael Smith]

From the article Berger recommends 1:8 twist. I don't think my 1:10 will stabilize the 170. I found couple of twist calculators online I will play with them. Giving the old girl some spark is really appealing to me.

 

[sedancowboy]

I don't think that a 1/10 twist will stabilize a 170 Berger EOL. you need a 1/8 with a long throat. bigngreen is the Master of all things 270 maybe he will chime in. Some 150s are hard to stabilize with a 1/10. I am getting better long range hits with a 1/8 and the 150s.

 

[Timnterra]

I've had a 270ai reamer and headspace gauges setting in my reamer drawer for a couple years wanting to build one. A couple years ago I bought a 1-8" twist benchmark barrel, but it was a heavy varmint contour and I really wanted a hunting rifle. It just seemed wrong to build a classic hunting rifle in 270 ackley with a 6lb barrel. I ended up selling the barrel and have been hoping for someone to change their mind and sell a #4 or #5 1-8" twist barrel. I guess I'll keep on shooting my standard 270 with 150gr LRABs. Which is no slouch as is, but with with1-10" barrel the 150's are the best bullet I can shoot.

 

[FEENIX]

From the article Berger recommends 1:8 twist. I don't think my 1:10 will stabilize the 170. I found couple of twist calculators online I will play with them. Giving the old girl some spark is really appealing to me.

To stabilize in 1:10", you will need to propel the 170 at least 3000 FPS and 7K'+ altitude ...

With my set-up, I should be able to get the 3K' FPS and at my altitude ...

 

[Big Jake Duke]

I just remembered both of my barrels are standard 1-10 twist. But the guys over at Rokslide shot the 165's and 170's and have done okay. Maybe if I find some AI dies for cheap I'll pull the trigger, so to speak

mine (270AI) is a 1-10 and it shoots the matrix 165s, the Nosler 150 LRABs and the Cutting Edge 130MTHs very well. I could never get the berger 170s to shoot even in a 1-8 twist. I would use the 130MTH on elk because of the bullet construction, it isnt too little.

 

[Big Jake Duke]

To stabilize in 1:10", you will need to propel the 170 at least 3000 FPS and 7K'+ altitude ...

View attachment 147651

With my set-up, I should be able to get the 3K' FPS and at my altitude ...

View attachment 147652

I had a 1-8 twist and 3300fps and I couldnt get consistent 4" groups at 100 yards. yes 100 not 1000. I had to give up that bullet- I still have 300 on my shelf!

 

[Big Jake Duke]

Back in Ackley's day the 270ai was not recommended because 4831 was the slowest powder they had beside some surplus machine gun powder. There was also the issue of no virtually no commercial bullets heavier than 150 grains. In a phone conversation with him years ago he said with more modern powders and better bullets that he would recommend it. He told me that when he chronoed the standard 270 vs the 270 weatherby that there was only about 125 fps difference then.
Powders have greatly improved since the 1980's. The 270ai is a worthy contender with the newer powders and better designed bullets. If there is a 270 sherman, that would be the optimum salute, to the 277 bore. I would go for it.

I actually got the best bag with Reloader 19 and the 150gr class bullets. 3200fps in a 26" barrel.

 

[FEENIX]

I had a 1-8 twist and 3300fps and I couldnt get consistent 4" groups at 100 yards. yes 100 not 1000. I had to give up that bullet- I still have 300 on my shelf!

WOW, 4" at 100 yards, yikes! Pushing the 170g at 3300 FPS is impressive. Unfortunately, this combination does not necessarily mean accuracy. My grouping opened up with FPS greater than 3000 FPS, so I back it off a tad for the best compromise of accuracy and velocity. Bullet stabilization with the right bullet twist is part of an accuracy equation. What stabilization supposed to do is help orient the bullet in flight as stable as possible to the target ...

(SOURCE: https://bisonballistics.com/articles/barrel-twist-and-bullet-stability)

 

[Big Jake Duke]

I didnt try the bullet slower, because I didnt build that cartridge to shoot sub 3000 speeds. I just had to drop that bullet from my line up. The funny part isa that I built that rifle soley to shoot that bullet. I thought that 3350fps and a 705 bc would be the best, but I couldnt get the geni into that bottle!

 

[FEENIX]

I didnt try the bullet slower, because I didnt build that cartridge to shoot sub 3000 speeds. I just had to drop that bullet from my line up. The funny part isa that I built that rifle soley to shoot that bullet. I thought that 3350fps and a 705 bc would be the best, but I couldnt get the geni into that bottle!

I am having a hard time understanding how you are able to push the 170 at 3300 FPS, is this velocity off your .270 AI or your .270 - .300 WM?

 

[Big Jake Duke]

I am having a hard time understanding how you are able to push the 170 at 3300 FPS, is this velocity off your .270 AI or your .270 - .300 WM?

VERY SORRY for the confusion. I never shot the 170s in the AI. It was a 1-10 twist. I did shoot the 165 Matrix's at 2950 in a 25" barrel. That was about full power plus in the 270AI.

The 170 speeds were in the 270-300 win mag. 28" barrel

 

[Nomosendero]

I have a M700 .270 that shoo9ts good. An AI would be fine, I have a 30-06AI & a 25-06AI, but if 6.5 RPM brass is high quality and decent price I might go .270RPM as a wildcat but may be commercial some day.