FPS 6br or 6brx

[lilgreg]

what FPS can be expected out of 26" or 24" bartlein 6mm 5r 7.5 twist in 6br or 6brx with 105 vld berger THANKS

 

[brxbrad]

Depending upon the load. I average 2850 with my 6BR 1:8 26" Shilen and 3000 with my 6BRX 1:8 26" Kreiger using 105 Bergers.

 

[racesnake]

I'm running 3050fps wiith the 105 VLD's Out of a 27" Kreiger. Reasonable pressure and extremely small vertical.

 

[lilgreg]

this rifle is a tactial switch barrel. it started as a 300wm build by landtec on a 700rem and a A2 McMillam toped with a M4 8.5x25 mil dot and 20moa rail. then later a bolt from David Kiff and a barrel from bartlein it can be a 308 smithed by Allen Custom Arms. Both barrels shoot very well. Iwould like to keep barrel length down as much as possible but don't want to loose to much speed THANKS

 

[20PPC]

I was going to post just this question today. I shot my BRX today across the chronograph and with a 26" Kreiger GT 8.7-8.2 105 Bergers and Varget I was getting 3210 ave fps. I wasn't sure what others were getting and it sounds like I am a little faster than most.

FORUM BOSS Warning: These velocities can NOT normally be reached with a 105-gr bullet in a 6mm BRX and Hodgdon Varget powder. Don't even try!!

 

[drumcorpschamp]

I was going to post just this question today. I shot my BRX today across the chronograph and with a 26" Kreiger GT 8.7-8.2 105 Bergers and Varget I was getting 3210 ave fps. I wasn't sure what others were getting and it sounds like I am a little faster than most.

Wow!

 

[brxbrad]

Say What............?

 

[lilgreg]

sounds fast I am leaning toward BRX is .269 a no turn neck THANKS

 

[Forum Boss]

I was going to post just this question today. I shot my BRX today across the chronograph and with a 26" Kreiger GT 8.7-8.2 105 Bergers and Varget I was getting 3210 ave fps. I wasn't sure what others were getting and it sounds like I am a little faster than most.

Hmmm... I assume "GT" refers to Gain Twist. I'm not aware of a gain twist offering that much more velocity. Suggest you might want to borrow a buddy's chrono and re-check those numbers.

Message for readers: These numbers are way off the chart. I've seen velocities like that with NINETY grainers in a 6mmBR improved but don't expect to get such velocities SAFELY from your gun with 105-108 gr bullets! Quickload suggest such velocities would require a pressure close to 76,800 psi in a BRX with 43.00 grains H20 capacity. Way way too hot.

 

[20PPC]

The chrono I used was a friends and I did question the numbers that is why I posted without any numbers on the powder charge. We did check the velocity on 2 custom 6br's with 12 twist barrels and both were shooting 80 gr. bullets. One of the guys showed 3180 with a untreated barrel and the other guy has a barrel that is Melonite treated and his velocity was showing substantially more. I had heard that you will get a increase in speed on a Melonite treated but I didn't think you would the numbers he was getting. The increases he was getting made me want to send every new barrel I get out for treatment but maybe it was just the chrono giving it up.

 

[Rustystud]

Not wanting to side track the original post. But this may be of interest. I compared 5 chronographs lined up in a row. one chrony, two CEDs one with white light and the other with ifrared, one Magneto speed, and one Oheler 35. With the same rounds fired over all, I got more than a 200 feet of extreme spread between the bunch. Thus I am saying not all chronographs are created equal. Ironically the most expensive and the least expensive were within 50 fps.

I have a little experience with the 6mmBRX with barrels from 26" to 33". With Varget 32. to 32.6 grains a velocity of 3000- 3080 fps can be achieved with 105- 108 grain bullets. With H4350, N-160 and VV550 I have acheived velocities as high as 3300 fps. But it ruins the brass in short order. The beauty of the 6mmBRX is accuracy and ecconomy (brass life 16 to 20 reloads).
Nat Lambeth

 

[hogpatrol]

Nat, It would be interesting to have the Magneto speed hooked up and also shoot through the screen types, the same shot. Have you tried that? Hog

 

[20PPC]

The rifle I have is a Bat SV with a 26 in. Kreiger gain twist 8.7-8.2 Mike Davis chambered the rifle and had mentioned that he had seen on a couple occasions where you would have to increase the load more for the GT barrels than for a standard twist. I am shooting Varget in the rifle and am waaaay above what Nat mentioned he was shooting and had gone even higher in my ladder test before any signs of pressure. I guess I need to try another chrono to try and find out what it is really shooting. I guess the numbers in all reality don't really matter as long as it is shooting well. My last 5 groups at 300 yards measured between .62 and 1.1 with a 15 mph wind. I guess it is shooting as well as I could ask for.

 

[MarkS]

Greg,
I had a 25.5" Krieger in 6BR. The best I could get was 2800 f/s. I had it punched to a 6BRX. I could run it up to 3050 f/s. The best accuracy with the 105's, is 2975 f/s.

Mark Schronce