N140 or N150 in a Straight 6BR with Heavies?
- Thread starter HTSmith
- Start date
Both will work very well. However, N150 will produce better velocity. Do you have a .236 or a .237 bore? I have had both and I much prefer the .237 bore. With an 8 twist .237 bore, try going from 29.4 to 30.4 with N150>>>> somewhere in there you will find it shoots great. With the Berger 108, try initial seating depth at 6-7 thousandths INTO the lands. CCI 450 primers..
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Both work, but over here in the UK the majority of match users of the cartridge choose N150. We've been doing this for some years now as H. VarGet became almost impossible to find here as long ago as 2012/2013.
It's difficult to overload the cartridge with N150 in a rifle properly throated for the heavier bullets. I'll stress 'difficult' as it's not impossible. A friend ran a 6BR 'Heavy Gun' a few years ago using an N150 charge that I'd have thought impossible to be accommodated in a 'straight BR' case. (He and his father make up 30-inch long drop-tube powder funnel outfits so this tool has to figure here somewhere, maybe a bit of vibratory settling too which they also use on occasions having made a tool up for that.) MVs too were really impressive for the 'straight' version and he and his daughter won a series of UKBRA matches with the outfit. Until ...... a couple of hundred rounds or so into the barrel life, pressure in the form of blown primers appeared and reducing charges in 0.5gn steps failed to cure the problem until he got down to 'usual load levels'. This was in a Benchmark barrel and this makes seems very prone to pressure / MV increases at around 200-250 rounds in 6mm calibre at least as it's not the first time I've seen this.
Usual loads here are between 30 and 31gn, the latter with some compression even with the Forster 5-inch drop-tube funnel, using the 105gn Berger VLD a bit into the lands. Lapua brass and Rem 7 1/2, CCI-450 or BR2 primers. My current 6BR barrel gives superb groups but modest MVs (2,700 fps from the 107gn SMK jumped 0.015) from 30.0gn 'old formula' N150. (Vihtavuori recently introduced a temperature stable upgrade to the powder, but reports say any load/performance/pressure change is marginal at most) This is in a very low round-count 30-inch Benchmark a twin of my friend's from the same production lot, so I decided to stick with 30gn which was chosen during initial barrel run-in shooting, until I see if the barrel changes with use.
I've no experience of the Dasher or other improved variants, but reports here on the AS Forum and from Dasher shooting friends say that N150 doesn't work nearly so well in this version of the cartridge for some reason.
It's difficult to overload the cartridge with N150 in a rifle properly throated for the heavier bullets. I'll stress 'difficult' as it's not impossible. A friend ran a 6BR 'Heavy Gun' a few years ago using an N150 charge that I'd have thought impossible to be accommodated in a 'straight BR' case. (He and his father make up 30-inch long drop-tube powder funnel outfits so this tool has to figure here somewhere, maybe a bit of vibratory settling too which they also use on occasions having made a tool up for that.) MVs too were really impressive for the 'straight' version and he and his daughter won a series of UKBRA matches with the outfit. Until ...... a couple of hundred rounds or so into the barrel life, pressure in the form of blown primers appeared and reducing charges in 0.5gn steps failed to cure the problem until he got down to 'usual load levels'. This was in a Benchmark barrel and this makes seems very prone to pressure / MV increases at around 200-250 rounds in 6mm calibre at least as it's not the first time I've seen this.
Usual loads here are between 30 and 31gn, the latter with some compression even with the Forster 5-inch drop-tube funnel, using the 105gn Berger VLD a bit into the lands. Lapua brass and Rem 7 1/2, CCI-450 or BR2 primers. My current 6BR barrel gives superb groups but modest MVs (2,700 fps from the 107gn SMK jumped 0.015) from 30.0gn 'old formula' N150. (Vihtavuori recently introduced a temperature stable upgrade to the powder, but reports say any load/performance/pressure change is marginal at most) This is in a very low round-count 30-inch Benchmark a twin of my friend's from the same production lot, so I decided to stick with 30gn which was chosen during initial barrel run-in shooting, until I see if the barrel changes with use.
I've no experience of the Dasher or other improved variants, but reports here on the AS Forum and from Dasher shooting friends say that N150 doesn't work nearly so well in this version of the cartridge for some reason.
shooting 108 gr Bergers in a two straight 6BRs with 30.3 grs of N140. these is a long throat barrels that shoots these loads with no pressure issues. MV around 2900 fps in a 30 inch barrel. i used to use Varget, but the N140 shoots better, more consistent vertical at 600 yds, with an ES around 10 and single digit SDs
What about N135? Too fast?
I have all 3 in my inventory, 135/140//150
I have all 3 in my inventory, 135/140//150
stacy
2 TIMOTHY 2 VERSE 15
YEP THE N-135 IS LITTLE FAST FOR HEAVYS BUT IT WORKS WELL WITH 80GR BERGER IN A 6BR SHOOTS LIGHTS OUT FOR ME
JEFFPPC
Gold $$ Contributor
I would certianly try it. I had a 14 twist and a 10 twist 6br barrel years ago. I shot 68 ,80,88, and 95 gr bullets. VV135w2as the accuracy power in both guns for all bullet weights. It might give you a bit less velocity but hey, accuaracy trumps speed. I would try it.
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josebd
Silver $$ Contributor
What was your loads on both powders?
My straight 6BR has a 27” 8 twist that’s 1.2” from Preferred Barrel Blanks. It has the 94 or 95 (can’t remember which one without going to look at my print) free bore JGS chamber spun up by my smith Mr. Jim Futch in FL. I tried N133, 135, N140 and N150 and a whole other host of powders as well as bullets. Mine shot N150 the best. I shoot N150 (30.4) with a velocity of 2900-2910 with no pressure. Pushing 105 Berger VLD Targets seated 20 off touch in Lapua brass and 450 primers. I have 16 firings on my brass with good primer pockets still and it’s won the last 3 midrange FClass matches it went to. I’ve since switched my 308 to N150 also. 140 and 135 pressured out around 2775-2800. Once again it’s my rifle work accordingly. But in my setup vv-N150 is the sweet spot. But I just tried some RL 15.5 yesterday for the fun of it and it shot almost equally to the N150. I was very impressed with the velocity and accuracy of it too. It actually worked out a bit more velocity without pressure. Varget is crazy different lot to lot and seems to be more sensitive to temperature or humidity changes here in FL. I shy away from it.
Allen Corneau
Silver $$ Contributor
Old thread, but... In my mind "heavies" would be 115 grain bullets, not 105s. That being said, I use N150 for the Berger 115's going 2,735-ish.
I heard a rumor that Berger was working on a 120 grain 6mm bullet. Probably geared toward the 6 Dasher, 6GT, 6CM, 6XC (etcetera) crowd. I wonder if it will be a standard boat-tail, hybrid, or VLD type of bullet.
I heard a rumor that Berger was working on a 120 grain 6mm bullet. Probably geared toward the 6 Dasher, 6GT, 6CM, 6XC (etcetera) crowd. I wonder if it will be a standard boat-tail, hybrid, or VLD type of bullet.
64Rambler
Gold $$ Contributor
Not BR but a lower node in 6 BRA, so maybe an upper node in 6 BR(?), I shoot 30.2gn N150 in Alpha brass w/ 107 SMK 0.006" IN on a 0.120 FB at 2850 ES 26 SD 7.2 and pulled off a 198-7X today. The 2 dropped points (shots 5 and 13) were missed wind calls - completely pilot error.
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