The 27 Nosler, it's official!

highdrum

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You’re confusing the length of the lead for the freebore
Okay so what you're saying, that saami chamber is basically zero freebore chamber, with longer throat than normal due to less leade andle?
 

Jud96

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6406CDC3-E72F-4AAE-AEC2-8B8BD407AD31.jpeg
The freebore is only 0.019, it does have slightly longer lead than normal as the andle is 1° vs 1.5°. The case has a long neck for 270 at 0.329 but you'll want more FB for a 170 Berger, as the bearing is 0.407, the neck helps you out way more than the freebore does. Freebore is the length after case mouth that's 277 diameter. Where the taper starts to the lands, usually indicated by a 1.X 30' measurement that's the start of the lead.
Here’s an image of the 6.5 PRC SAAMI spec reamer, it sure has more than 0.016 of freebore. The lead length is 0.016 and the freebore is 0.205 according to that print.
 

Jud96

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Okay so what you're saying, that saami chamber is basically zero freebore chamber, with longer throat than normal due to less leade andle?
No. What I’m saying is you’re confusing the lead length (0.019) for the freebore. The freebore would be measured by subtracting the case length plus the lead length (2.619) from the 2.7718 dimension. That gives you 0.159 freebore. Some people add the length of the lead plus the freebore, so essentially it gives you 0.178 of freebore. That’s a good bit and plenty for the 170 EOL.
 

Capt RB

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My goto hunting bullets have been noslers for 4 decades. I can usually get them to shoot well and they flat out kill stuff. Huge 270 fan so it looks like I will be ordering a 8.5 twist
 

highdrum

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No. What I’m saying is you’re confusing the lead length (0.019) for the freebore. The freebore would be measured by subtracting the case length plus the lead length (2.619) from the 2.7718 dimension. That gives you 0.159 freebore. Some people add the length of the lead plus the freebore, so essentially it gives you 0.178 of freebore. That’s a good bit and plenty for the 170 EOL.
Freebore stops where the chamber is no longer 0.278 diameter(2.619 on print) , at that point the lead/throat starts which tapers from 278 to 270 at 2.771". The bearing surface of the bullet is 277 diameter. That will only go into the throat maybe 30-40 thousandths before it engages the lands. Any more than that you're jammed. This chamber has nothing close to 178 freebore. Freebore is usually 1 thou larger than bullet diameter. This chamber has essentially no freebore.
 

Westernhuntr

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Another way over bore Nosler.. Great.
My 28 nos lost accuracy in less than 400 rounds.
For the life of me I can't see why the 33 nos has the least capacity, but the greatest potential.
The 270 wsm in a med action is perfection why screw with it?
Im with the guys who are more excited about the 165 Ablr
 

rfurman24

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Technically the 27 Nosler has zero freebore because the first number is just the transition from the neck to the throat (2.619-2.600) and .1528 lead(2.7718-2.619).
 
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Jud96

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Freebore stops where the chamber is no longer 0.278 diameter(2.619 on print) , at that point the lead/throat starts which tapers from 278 to 270 at 2.771". The bearing surface of the bullet is 277 diameter. That will only go into the throat maybe 30-40 thousandths before it engages the lands. Any more than that you're jammed. This chamber has nothing close to 178 freebore. Freebore is usually 1 thou larger than bullet diameter. This chamber has essentially no freebore.
You’re right. I had a major brain fart. Good thing it has a long neck. If I were to build a custom I would definitely throat it to have 0.150 Freebore or so. Sorry for the back and forth, I was completely overlooking the dimensions.
 

Jud96

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It has .188 freebore and .16 lead.
Yeah it’s 0.188 Freebore technically. I just added the length of the lead to the freebore. You’re right, but I just add the two together because that’s really how much bearing surface can be outside of the neck before engaging the rifling. Tonight has not been my night for studying reamer prints haha
 

nvschütze

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… … without the belt.
Belts are useless in today's rifles. They may have been used in the Dark Ages to headspace the round, but they are just superfluous remnants of ancient design in these modern times. I was a member of one site years ago that had a member whom machined-off the belt on his .300 Weatherby cases. As both a machinist and a rifle builder, he had to know that what he was doing would not be detrimental toward the performance upon the target of the end product.
 

nvschütze

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Presently have a 35 Whelen .. .. ..
You may have liked my .358 Sierra Stomper. It was exactly what the .35 Whelen would have been had the Whelen had been formed on a .532" case. It was pure punishment to fire it. The recoil in a nine-pound rifle was vicious. It produced 4092 foot-pounds of muzzle energy behind a 250-grain bullet at 2715 fps. I was good with it for about a dozen rounds. After that many, I got so flinchy that I just couldn't fire it any more for the day. It was accurate, producing 3/4" groups at 100 yards with 60.0 grains of IMR-4320 and that 250-grain bullet. I built the rifle just to see if I could attain 4000 foot-pounds of muzzle energy. I did, in fact, mightily succeed...
 

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Capt RB

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Dec 1, 2014
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It's funny reading the specs this morning. 2880fps for the 270 win 3000 for the wizm and 3165 for the wby. I load the 140 tgk to 3140 because it shoots best there. The 150 sst/interbond shoots best at 3110 along with the eldx The 130 is at 3139. All can run much faster 50-80fps before pressure in low capacity brass and 100ish in Winchester brass. I would hope throated for the big bullets with LRT Rl 33 8133 you would see 3400 with the 165 170 class of bullets without issue. To combat the erosion a company that is at the shot show is developing nanotechnology for its line of cartridges. These are like the new sig round with bi-metal cases running 80K psi.
Hoplite arms are the name of the company. I may try to see if I can come up with something similar. I'm a huge fan of dry lubes on bullets. On comp guns not named 308 and fast coyote guns, I have stuck with Danzac with exceptional results in both speed and barrel life.
 

Wolf76

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Jan 5, 2014
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Grandville, Michigan
I always wonder with over bored cartridges "is it worth the extra..."? Will 1-2 hundred fps make a Real Difference in terminal performance at normal hunting distances <500? Maybe if the cartridge is marginally adequate. Between the extra powder, recoil, and faster barrel erosion - is it worth it? No hate towards anyone that goes for it and I have a 257 weatherby, so I'm talking from experience.
From a marketing perspective it makes complete sense -26,27,28,30,33,35 cals.
 

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