270-300 Win Mag now feasible

[royinidaho]

I have a 24" 1-10 barrel that I am working up for a 130gr bullet…are we talking about a standard 270Win cartridge ?

Yep, 270 Win

 

[Big Jake Duke]

BJD,

What kind of velocity are you getting from those 130 MTHs and do you think they'll work in a 10 twist.

I'm pereping a vintage 270 Win for max performance and for some weird reason don't want to shoot any heavier than 130 grain offerings.

I'm messing with CEBs in 375 cal but no experience in the 270 arena.


MY 270 AI is a 1-10 twist. The barrel is 25"( it was a 26 " 270win, but when i shot the throat out i had them reset the chamber as an AI). I get 3300+ with the 130gr CEB.

They are highly accurate bullets

 

[Big Jake Duke]

I have a 24" 1-10 barrel that I am working up for a 130gr bullet…are we talking about a standard 270Win cartridge ?[/

I shoot a 270win AI. It is an improved version of the 270 win. It will add about 200 fps on each bullet weight in my experience. It is made by rechambering an existing 270. There are a lot of naysayers, but it has been a great improvement for me.

This thread is about necking down a 300win mag case to .277. The shoulder angles are all the same as a 300 win mag. I imagine you coud do it with an existing 270? But thr bolt face would have to be altered and the mag box may be too short.

I rebarrelled an existing 300 win mag. And i used the Pacnor 1-8 twist barrel for the higher bc bullets.

 

[Big Jake Duke]

So i had settled in with the Cutting Edge 140grs at a 590 bc and 3450fps, and then look at what just came in the mail!

Now I'll be busy this weekend too!

 

[royinidaho]

So i had settled in with the Cutting Edge 140grs at a 590 bc and 3450fps, and then look at what just came in the mail!

Now I'll be busy this weekend too!

FYI, I was pushing the 140 class bullets out of the 270 AM @ right around 3600 w/mobious amounts of US-869. 99 to 101 grains.

I'm leaning heavily towards rebarreling that thing to a 270-300 Win. It's pretty much a no brainer. The 270 AM is limited to ball powders and I'm thinking the 270-300 barrel will last at least twice as long as the improved RUM chamber with enough performance to hunt anything Idaho has to offer.

Keep up the good work.

 

[CogburnR]

I ordered my 270-300wm finally after debating about it for 3 years.

Next week I am going to unscrew my barrel and send in the receiver to Pac-nor.

I am interested to see the results of your testing the 170 Bergers!

 

[Big Jake Duke]

Ill get itvtested tomorrow and let you know- make sure to get the fast twist barrel.

I chose a 28" #6. Pacnor chambered and headspaced, then dissasembled it and shipped it to me. After that i had the barrel nitrided and since the headspace sits like a 300 win mag my local gunsmith put it back together for me.

 

[CogburnR]

I ordered a 28" Stainless Super Match Sendero contour in a 5 land/ 8 twist with the .309" neck and the floorboard crown.

It goes on a Winchester Laredo M70CRF action that is currently a 300WM.

 

[Big Jake Duke]

Sounds awesome! What is the wait?

 

[Big Jake Duke]

Ugghhhhh


The load i had developed for the berger 170s was a total flop. The velocity was there, but i couldnt keep groups in the same zip code.

So i will set up a ladder in .2 gr increments and hope i find a happy node.

I tried US 869 which had done so well with the other bullets.

I will attempt Retumbo and a new ladder of 869. I still dont have any H1000 to try.

Would anyone like to try some Berger 170s? I have 5 boxes

 

[bigngreen]

So i had settled in with the Cutting Edge 140grs at a 590 bc and 3450fps, and then look at what just came in the mail!

Now I'll be busy this weekend too!

You have to watch the CEB BC numbers, some are close some are not, .590 is not reality for that bullet, I would expect closer to .480. There are Litz bc numbers for the 120 and 130 and there significantly lower than advertised, they will not be higher than an equal weight Berger.

 

[royinidaho]

Ugghhhhh
The velocity was there, but i couldnt keep groups in the same zip code.

I tried US 869 which had done so well with the other bullets.

I will attempt Retumbo and a new ladder of 869. I still dont have any H1000 to try.

Would anyone like to try some Berger 170s? I have 5 boxes

Hmmmmm :roll eyes:

I am quite surprised by your results!

What was your velocity?

My experience with 169.5 Wildcats and 190.5 Wildcats in the 270 Allen Mag with charge weights of 93 to 101 grains of US-869 is that while she shot great with specific charge weights, ESs were never acceptable. However I did, more often than not, smash rocks way way out there.

In other words I have no love or respect for 869. However, it was the 'only' powder I could use with heavy bullets in that cartridge.

Why she would do so well with other bullets and come unglued with the 170 Bergers is certainly a head scratcher. There is no reason, that I can think of, that would be caused by powder choice.

By 'same zip code' do you mean 'field of view of the scope' which I have experienced? One instance I had to have a fella on the next bench spot for me. He had to switch from spotting scope to binos and finally to naked eye to spot impacts. Bullets were hitting everywhere from under 100 yards to well beyond 500 yards and wider than the range shooting lane when I was shooting 300 yds.

However, if your punching holes somewhere on the target/backer is there any 'pattern' at all? Different patterns indicate different things.

I'm closer today than yesterday on a 270-300 Win build and have a strong desire to shoot 170 class bullets. Either Bergers or Dale Jensen's from Canada.

As is said, "experience is the best teacher", this time I'm glad that experience is yours. Cause I've had my fill of mine with this kind of stuff..

 

[Longtooth32]

Ugghhhhh


The load i had developed for the berger 170s was a total flop. The velocity was there, but i couldnt keep groups in the same zip code.

So i will set up a ladder in .2 gr increments and hope i find a happy node.

I tried US 869 which had done so well with the other bullets.

I will attempt Retumbo and a new ladder of 869. I still dont have any H1000 to try.

Would anyone like to try some Berger 170s? I have 5 boxes

I posted this pic in the bullets and rifle section…

This was shot with H1000, 170 Bergers, 3.4" mag length, in my 270 Wby, 1-9, 28" Benchmark. I am at work, so I do not remember the grain loadings… first group was shot in the low 3000fps and the last group was in the low 3100fps…I think I can hit the accuracy node at around 3150+fps. A lased 103 yards.

I was shooting out of the back of my pick and the wind was rocking the truck. I finally gave up when my chrono would not stay up in the wind.

Retumbo was giving me terrible groups…7977 was showing promise...

 

[Big Jake Duke]

Roy-

By zip codes i mean 3-4". I think it is a bullet jump and fine tune tenths of grains issue. I was just bummed because everything else rocked right out of the gate. Cant be too easy though right?