450Bushmaster.net

First range report to this.
Gun: RAR
Bullet: Barnes TSX 275
Brass: Starline
Primer: Rem 7 1/2
Powder: N120
COL: 59,4 (front side of first groove)
Temp: about 18C

Load(grains) Velocities
35.0. 1766. Lot of soothing
37. 1689. Lot of soothing
38. 1733, 1746. Soothing
39. 1800, 1804, 1769. Minor soothing

39 grain load did 15mm group @50m with old scope and 4* magnification.

Will fine tune loads from 39 to 40 grain and test more. 40 grain is about full load, and anything over it will be compressed load.

I know nothing about that powder but as for the sooting, that may be caused by not enough energy to expand the case against the chamber walls before the bullet releases and some of the gasses bypass back into your chamber. Not an ideal situation. First check your crimp to be sure it’s firm enough to hold the bullet during ignition. And you might consider a hotter primer. But what I found to be the case with a different powder was that I didn’t have quite enough energy in the form of chamber pressure to seal the case against the chamber wall. I was using LilGun. When the sooting stopped, I also found an accuracy node soon after. I think it was around 41.0 grains of Lil Gun when I was loading those 230 FMJ flat points a few years ago. Go back and check my range reports. But since I don’t know this Finnish/Swedish powder you’re using, I cannot make any suggestions on your next step. But stay safe and I’m definitely going to be watching your progress. Thanks for the report.

My own guess at this point is that I will run out of case capacity before I get pressure signs on bolt action rifle. Maybe I also try to make col longer and crimp between cannelures.

LeaderOfThePack wrote:My own guess at this point is that I will run out of case capacity before I get pressure signs on bolt action rifle. Maybe I also try to make col longer and crimp between cannelures.

Have you actually measured your chamber?

this is where I crimp the 275's for my bolt guns and #1 Ruger.

2.410ish keeps it about .050 off the lands and will give you some extra case capacity with that N120.

Here’s mine. But it’s for the AR15. My RAR and my single shot have a longer COAL.

I have measured it, but will confirm that. Result: 2.41.

I think you might get better results with N110, that's what I use and I get zero sooting.

For 275gr TSX? What kind of loads you have tested? My purpose was to use N120 so I can get best possible speeds, but case capacity seems to be limiting factor.

I don't know anything about Vihtavuori powders, but your sooting is under control, and your at a compressed load sounds like it's too slow. That and your only at 1800fps. Try something faster.

Edit - Just looked at a burn rate chart, now I know these aren't always accurate depending on application, but they get you in the neighborhood. N120 is rated slower than 4198, which is slower than 1680. 1680 is hard to get full burn with 300gr bullets. Now with a COL of 2.4, you might be able to get it going with this bullet, maybe.