What .277 barrel and twist?

[ducky]

I'm looking at building a couple of .277 cal rifles. My GS recommended Pac-Nor, he said their 1:8 twist barrels are shooting great in his builds. I've got some sample bullets coming in from a generous member, @Bghunter338.

Just looking in the picture he provided of the bullets, to say they're long is an understatement. I'm looking at rebarreling a M670 .30-06 to .270 Win, and my M70 .270 WSM to shoot these. Should I look for a faster twist than 1:8 to handle these bullets, especially in a .270 Winchester? I live and hunt CO mainly 4000 ft to above timberline. I just want to insure these bullets will stabilize.

10- Nosler BT 170gr
14- Sierra TGK 175gr
10- Maker T-Rex 160gr
10- Hammer HT 160gr

I'm going to load up a few dummy rounds and see how they fit the magazines before moving forward on the builds.

 

[FEENIX]

I'm looking at building a couple of .277 cal rifles. My GS recommended Pac-Nor, he said their 1:8 twist barrels are shooting great in his builds. I've got some sample bullets coming in from a generous member, @Bghunter338.

Just looking in the picture he provided of the bullets, to say they're long is an understatement. I'm looking at rebarreling a M670 .30-06 to .270 Win, and my M70 .270 WSM to shoot these. Should I look for a faster twist than 1:8 to handle these bullets, especially in a .270 Winchester? I live and hunt CO mainly 4000 ft to above timberline. I just want to insure these bullets will stabilize.

View attachment 632579

10- Nosler BT 170gr
14- Sierra TGK 175gr
10- Maker T-Rex 160gr
10- Hammer HT 160gr

I'm going to load up a few dummy rounds and see how they fit the magazines before moving forward on the builds.

I built my .270 AI in 2012 primarily to propel heavy bullets—165/175 Matrix. I have a 30" 3G 1:8" barrel from Lilja. If I had to do it again, I would go with 1:7", which they now make. I have 2 Lilja 3Gs and am very pleased with them—they are very easy to clean and hardly have any fouling. Good luck!

 

[Bghunter338]

Yes, definitely go with a 7 twist. You still can shoot the heavier cup and cores to.

 

[Hand Skills]

1:8 will limit your choices some, for example;

Maker recommends 1:7 for those 160's

If you want to shoot heavy for cal monos, definitely go 1:7.

6.8 Western comes standard with 1:7.5 twist for reference.

 

[David_h]

I have a 7.5 twist 6.8 Western and I chose not to shoot the 160gr Hammer HT. Instead I shoot the 151gr Hammer HT for more terminal stability when the projectile hit the animal (ie. less deflection I hope!).

 

[ducky]

Maker recommends 1:7 for those 160's

I had read that on their web page. I was going to stick with cup-n-core bullets mainly, but I guess Bghunter338 thought I should look at the monos as well. The 155 LRX is definitely on the table as well but it only needs a 1:8.

 

[Hand Skills]

As far as I know, 1:8 will stabilize any cup-n-core in .277 - the Sierra 175 being the longest and heaviest I am aware of, but if you are shooting loooong distances a 1:7 may help out the BC some (most of the time faster spin = higher BC)

Like @David_h mentioned, higher SG (gyroscopic stability) can help with terminal performance too. With monolithics, a lot of guys are looking for an SG of 2 which seems to help with consistent expansion/rapid petal shedding and straight line penetration.

Good luck in your quest, keep us updated on the progress!

 

[Lou270]

Havent tried the heaviest monos but have shot 165/175 matrix, 155 barnes, 156 HH, 170 btip, 165 ablr, and 175 tgk all in 1-8 270 wsm or 6,8w. All super accurate. So long as go with what manufacturer recommends will be good

Lou