Best #grooves & twist rate for 24" .280AI?

[Scott Spencer]

I have a new (less than 80 rds through it) Ruger M77 Hawkeye and I am thinking about putting on a 24" Pac-Nor barrel on it. I am considering doing it in a .280AI so I was wondering what would be the better number of grooves - 3 or 5? And what twist - 8, 9, or 10? I plan to mostly shoot the 140 AB but could also step up to the 160 Partition and/or 160AB if I ever needed to.

Thanks!

 

[JD338]

Scott,

Sounds like great project.
My 280 AI has a Hart #5 conture fluted 24" 6 grove barrel. No problem shooting 120, 140 and 160 gr bullets.
Sorry, I can't help you with the 3 vs 5 grove barrels, I have only used 6 grove barrels.

JD338

 

[old #7]

Just tell Pac-Nor to give you the same barrel they make for the Nosler customs and don't worry about it.
I don't know what twist rate it is but it is one accurate rifle.

 

[Desert Fox]

For your 280, I'll opt for 9 twist. Number of groves doesn't matter . I do own a 3 grove, 12 twist Pac-Nor on my 308, and it's capable of phenominal accuracy.

Here's a 3 shot group at 510 yards.

10 shot group at 110 yards

 

[DrMike]

Scott,

I would think that a 1:10 would work just fine for 140 to 160 grain bullets. The 1:9 twist would work well for the 160 grain bullets, but would likely be a little fast for the 140 grain bullet. In theory, the more grooves the more accurate the barrel. In practise, it likely makes little or not difference. It would be worth discussing this with Pac-Nor. Were I buying, I'd probably select a 1:10 in 5 groove configuration, although the Nosler Custom is 1:9 twist.

 

[30-338]

This is something I copied from 6BR
What Is the Best Number of Grooves? Barrel-makers report that, as long as the ratio of lands to grooves is relatively constant, there is no demonstrable difference in accuracy among 3-,4-,5-,6- and 8-groove barrel designs. Krieger has told us "There isn't any advantage to the shooter. Assuming the ratio of the surface area is kept the same, the number of grooves should not have any effect. Barrel makers use different numbers of grooves for ease of manufacturing and ... marketing hype." That said, in our experience, 8-groove barrels are a little slower, and may foul a bit more quickly because there are more edges to cut into the bullet's jacket and to trap powder residue. We see no reason not to specify a 4-groove barrel if that is your preference. Moreover, IBS Hunter Champion Al Nyhus and others have had great success with Lilja 3-groove barrels. Al believes the 3-groove design cleans up more quickly and yields a bit more velocity. Famed gunsmith and wildcatter P.O. Ackley believed that, all things considered, a properly-made 3-groove barrel is optimal for most common calibers. Ackley believed 3-groove profiles can deliver higher velocities with less fouling and no significant reduction in accuracy. In the months ahead, 6mmBR.com plans to do a comparison test of various barrel formats.


My wifes 280AI has a Kreiger 25" long 1/9 twist 4 groove barrel and have only used 150gr bullets in that rifle. The 280AI and 284 I'm having build I'm using 9 twist barrel both have 3 groove barrels and I plan on shooting 150/160gr bullets

I agree with Dr. Mike and call about what twist and they also get feed-back on their barrel.

Well good luck

 

[Scott Spencer]

Excellent thoughts and replies, fellas! I'm getting good accuracy with my factory barrel but I'd like a little more velocity and consistency. I just love this Ruger Hawkeye .280 and I think the Pac-Nor, in .280AI, would be a great barrel....Especially since Nosler is willing to put their name on them with their rifles.

Jim - do you like the 26" barrel or would you opt for a 24" looking back now? I have one rifle (Mod 70 in .338 WM) that has a 26" barrel and that sucker is LONG!

 

[jmad_81]

Scott I was having that very same debate about the lenght. I'm in the process of building a 280 AI on a savage 110. Will be ordering the barrel from Pac-Nor as well. Looking at a #3 stainless super match. Was torn between going 25" ( for speed, not that 1 inch will amount to anything in real life other than the cool factor) , and 24". I thought about going 26" but my Win M70 338 WM has a 26" and as you stated, they do stick out there a bit. I'm wanting this rifle to be a fairly light weight one for mountian type hunting, but the extra 2" of barrel doesn't add that much weight. It just makes it 2" longer, a bit faster, and not a nimble to handle. Let me know what you decide.

I will more than likely go with a 5 groove 1:9 twist. Just so I can shoot some 162 A max, or 186 Bergers out of it.

 

[jmad_81]

According to the Pac-Nor weight calculator there is only .15 lbs difference between the 24"and 26" #3 contour.

 

[JD338]

Scott and Jake,

My 280 AI has a 24" barrel and I get some pretty good velocity with it.
140 gr up to 3240 fps and 160 gr 3019 fps from a well balanced and manuverable 24" barrel has a lot of advantags and in my opinion far outweighs the slight velocity gains from a 26" barrel.
I would go 24". :wink:

JD338

 

[DrMike]

I would go 24".

+1

24 inch is sufficient. You won't wring enough velocity out of the extra two inches to justify the clumsiness.

 

[Scott Spencer]

My reading comprehension sux, Jim! :grin: I see that you said 24" and for some reason I was thinking 26". Looks like Jake and I are on the same path as well.

Ok, with Jim & Doc saying 24" then I suppose that is what I'll do. I like the idea of a 24", 3 groove (just to be different), and with a 1:9 twist.

Would you guys just have Pac-Nor go ahead and fit my barrel to my action? It looks like it would be about $580 for them to do it all. Or would you try to find a local guy to do it? I've got a gunsmith about 80 miles from me but I don't know what he'd charge (I suppose I need to ask him. lol).

Last thing to do now is raise the rest of the cash to get this all done.... :lol:

 

[JD338]

Scott,

My questions to you and the rest of the fellas here is-
-Pac-Nor makes great barrels but how good are they at fitting them to the actions?
-Does Pac-Nor blueprint actions?
-Is Pac-Nor experienced at chambering AI? Proper chambering will has a slight crush fit on virgin parent case.
-Do you know of any body that has a fitted action from Pac-Nor?
-What kind of accuracy can you expect from them?

Compare your expectations to these answers and you should know what direction you need to go. I have nothing against Pac-Nor, I just don't know much about them. That is why the questions. I would do the same with any gunsmith I was considering.
The gun smith I chose I got to know working some hunting shows. After 3-4 years of talking and seeing his work, different rifles and their targets I felt confident he knew what he is doing. He didn't disappoint either! In fact I have sent a few friends to him and they were very happy with the results. His prices were competitive but more than what you are quoting.
just saying...

Hope this helps.

JD338

 

[jmad_81]

I have a good friend of mine tht has Pac-Nor do all his work. They do blue print, chamber, flute barrels, and remington bolts. I have only heard one bad thing about Pac-Nor's smithing. They cut the throat WAY to long. He sent it back and they fixed it and got it back pretty quick. His guns range in size from .22-243, 6-06, 280 AI, 338-06 AI, 375 H&H. He has had these Pac-Nor done rifles as long as I have known him (over ten years), and he won't keep a rifle that doesn't shoot under half inch. I think Nosler puts all the NC 280 AI together at their place.

If I wasn't doing it on a savage action I would have Pac-Nor do it in a heart beat. I am sending them a dummy round so they can cut my chamber to my specs. Next rifle up after the 280 AI will be my 338 WM getting a new tube. They will do that for me as well. It helps that they are within a days driving distance of my house. I have heard a bunch of stories about people not getting guns back for over two years. Never heard a story like that about Pac-Nor though.

I think they will do you a fine job.

 

[JD338]

Jake,

Thanks for the G2 on Pac-Nor, good to know!

JD338

 

[Scott Spencer]

I am sending them a dummy round so they can cut my chamber to my specs.

Jake - when you say dummy round, are you sending one with the overall length you want? Is it the longest bullet you'll use? The shortest? I am showing my ignorance here on the process but what are you sending them and how do you determine what to send them?

I know just enough of the chambering, throats, etc, to be dangerous but not enough to know what the hell most people are talking about. I have always been just a shooter of what I buy off the shelf and have never learned things that I should have.

Thanks!

Scott

 

[JD338]

Scott,

You can provide a dummy round to the gunsmith so he knows how much throat to cut.
My throat is cut long which allows me to have a much longer COL and more powder case capacity. If the long bullets are seated too seep into the case, it eats up powder capacity. I can load to over 3.5" COL in my rifle.

JD338

 

[jmad_81]

I'll send them a round with no primmer or powder, with a 160 AB that is a little shorter than what I can fit in my mag. This gives me room to chase the lands as the barrel wears out. My mag is shorter than JDs I think the longest COAL i'll be able to go is 3.330" and that leaves me .015" to chase the lands.

 

[JD338]

Jake,

A COL of 3.513 will touch the lands in my rifle and I still have room in the magazine. I also have a lot of room in the case for powder. :wink:

I have to give all the credit to my gunsmith, he has built quite a few 280 AI's so he know what he is doing.

Scott,

I hope this is making sense to you.
Let me know if you need anything.

JD338

 

[woods]

My 280AI was done by Hart and is a 26" long 1 in 8 twist barrel 6 groove

My intention all along was to shoot the 160 gr AccuBond and it does that very well at 3000 fps+. Also figured I could cut it down to 24" if I wanted to. I think it is perfect just the way it is and it does not create a problem for me, feels and balances perfect

I like to get the end of the barrel out there for balance and to get the muzzle blast away. I hunt with the 26" barrel without ear protection and it never rings my ears like my 24" 300 win mag does. The shorter the barrel the more the muzzle blast.

I just recently got a Pac-Nor 3 groove barrel for a 375 Ruger and I have to say I am mightily impressed. It fouls the least and was the easiest to break in of any barrel I have and I am getting 2975 fps with a 260 gr AccuBond out of it so it is fast.

I might try one of the 5R (ratcheted) or 5C (canted) rifling barrels for my next one but if not the second choice would be another Pac-Nor 3 groove.