Yeah, lack of freebore its like sticking a throttle governor on 6-pack Barracuda!. So everyone who builds a 27N will put it in LA with "sufficient" magazine COAL.
27 Nosler
- Thread starter Muddyboots
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Here is the Sammi Drawing. it is true.
The Hock
Well-Known Member
I bolt a 27 Nosler and had a reamer made so the Berger was at the shoulder because I'd thot it had a short throat. I love the rifle. Shoots lights out. But comparing the reamer drawing to the SAAMI change drawing mine has significantly less freebore! The factory chamber would be tough to reach the rifling.
I'm having a 270 WSM built with a fast twist and bullet seated out. SAAMI reamers have a long throat and my gunsmith's reamer has too little freebore so I'm back to buying a custom reamer.
The long throat fat twist 270 Winchester has interested me. I am going through a 300 Norma Improved build instead.
I'm having a 270 WSM built with a fast twist and bullet seated out. SAAMI reamers have a long throat and my gunsmith's reamer has too little freebore so I'm back to buying a custom reamer.
The long throat fat twist 270 Winchester has interested me. I am going through a 300 Norma Improved build instead.
I have the reamer you want on file at JGS Precision. Let me know and I will release a copy for you.
I also have a 270 WSM reamer on file for the 170s and long throat.
nralifer
Well-Known Member
The 140 SBD2, .277 caliber, is a bullet manufactured by Badlands Precision. G7 BC is 0.333 and G1 is 0.650. Recommended twist is 1:8
nralifer
Well-Known Member
Attached is the revised SAAMI chamber print showing a 0.152" free bore. Full view of the chamber print available on SAAMI site. Free bore diameter is 0.278"
Attachments
nralifer
Well-Known Member
That is a very significant velocity difference between two bullets with essentially the same BC. The copper bullet will be able to perform the best at close distances because of the inherent toughness of the bullet.
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If it reads anything ".270" I am interested in it. If you are reading this thread and contemplating building a .277 caliber rifle, it might be worth reading this reply and then doing some research on your own. A few years back I was looking to build a rifle that was a "wildcat" cartridge; however...had some difficulty figuring out what it was going to be. I was thinking about settling on the .280 Ackley Improved, but got disgusted with Nosler when they decided to differ from the Ackley principle of using the actual donor case, and instead developed their .270 Ackley Improved to meet "their"SAAMI specs. I refused to be held hostage to marketing for a manufacturer of ammunition. So after some long thought and research I decided on the .270 Ackley Improved. According to P.O. Ackley, some 50+ (?) years ago, stated that the .270 Winchester was already an overbore cartridge and not worth improving. Well that was 50+ years ago and the powder technology was not what it is today.
Unless one has to eek out every FPS and ME out of a .277 caliber bullet, the .277 Ackley Improved might be a consideration, and...I'll probably get beat up here, but the cartridge is not too far off of the heals of the 27 Nosler for ballistics. I sometimes shake my head in amazement when I read some of the marketing touting that these companies do. My son and I both have .270 AIs, built on Ruger 77 actions that have been trued, with 26 inch Lilja 1:10 barrels, pillar bedded/glass bedded/floated barrel that have been contoured to Ruger's barrel dimensions. Due to the thin barrel I call these rifles our "two-shot" guns because of the wispy barrel the third shot tends to wander. We can get around 3300+- with 150gr ABLRs, but this load is tough on brass/primer pockets. We've found that 3100 fps seems to be an accurate load for what we have built. For me personally there are a lot of pluses for this cartridge over the 27 Nosler. First and foremost is that components are readily available and affordable. I just ran a search for 27 Nosler brass, it was $111.99 for 25 cases @ $4.48/case, and....out of stock!!! I also question the barrel life on the 27 Nosler. I just did a quick search on load data for the 27 Nosler and 150gr ABLR and found load data that ranged from 76 grains to 89 grains and those velocities ran from 3200-3400 fps depending on the powder being used. We're getting 3100fps with 56.6 grains of RL15. There is a forum member on here who likes the .270 Ackley Improved, FEENIX, and could help fill in the blanks for anyone who would like to consider building a .277 caliber. He certainly is a very knowledgeable and helpful person who is a wealth of information when it comes to the .270AI. And if memory serves me correct his rifles are set up for the heavier, high BC bullets. I have attached a couple of photos of the cartridge and one of the 300 yard targets.
Unless one has to eek out every FPS and ME out of a .277 caliber bullet, the .277 Ackley Improved might be a consideration, and...I'll probably get beat up here, but the cartridge is not too far off of the heals of the 27 Nosler for ballistics. I sometimes shake my head in amazement when I read some of the marketing touting that these companies do. My son and I both have .270 AIs, built on Ruger 77 actions that have been trued, with 26 inch Lilja 1:10 barrels, pillar bedded/glass bedded/floated barrel that have been contoured to Ruger's barrel dimensions. Due to the thin barrel I call these rifles our "two-shot" guns because of the wispy barrel the third shot tends to wander. We can get around 3300+- with 150gr ABLRs, but this load is tough on brass/primer pockets. We've found that 3100 fps seems to be an accurate load for what we have built. For me personally there are a lot of pluses for this cartridge over the 27 Nosler. First and foremost is that components are readily available and affordable. I just ran a search for 27 Nosler brass, it was $111.99 for 25 cases @ $4.48/case, and....out of stock!!! I also question the barrel life on the 27 Nosler. I just did a quick search on load data for the 27 Nosler and 150gr ABLR and found load data that ranged from 76 grains to 89 grains and those velocities ran from 3200-3400 fps depending on the powder being used. We're getting 3100fps with 56.6 grains of RL15. There is a forum member on here who likes the .270 Ackley Improved, FEENIX, and could help fill in the blanks for anyone who would like to consider building a .277 caliber. He certainly is a very knowledgeable and helpful person who is a wealth of information when it comes to the .270AI. And if memory serves me correct his rifles are set up for the heavier, high BC bullets. I have attached a couple of photos of the cartridge and one of the 300 yard targets.
Attachments
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The Hock
Well-Known Member
Some 270 Winchester brass today is pretty good stuff! After a lifetime of shooting the Winchester and building a 27 Nosler I went with the WSM and a fast twist barrel. We'll see how it plays out. With the bullet seated out it's effectively a new cartridge as was the 27 with the bullet seated out. Any more I like a heavy bullet since the fast light weight bullets seem to ruin more meat.
Even plain Jane .270 Win, 27" Light Palma, 1:8tw, 0.290 freebore, 700LA to max magazine COAL 3.63 with 156HH with RL26 touched 3300 and settled load is 3200. 3X firing primer pockets still very good. Heck of lot less powder to get pretty close to 27N.
If 27N cannot do the following, no point.
If 27N cannot do the following, no point.
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Trm82
Well-Known Member
Those 270 AI are sexy little rigs.
I want one now !!
nralifer
Well-Known Member
The 140 SBD will get you to 1000 yds with far more energy because of the substantial BC advantage. Do the math and see.
