New to 6br, 105's at 100yards?

[Purcell429]

Hi all, new to 6br, picked up a Savage F Class and have only gotten in a session or two with it so far, but had a question about the 105 vs 90g Lapua ammo. Was able to do a quick sight in at 200 with both when I first got it with some success, then came back with a proper front rest to test at 100 yards last weekend. The 90's shot 4 3 shot groups: 0.26moa, 0.26, 0.27 and 0.29, plus a 5 shot group of 0.41, which I was pretty happy with.

Switched over to the 105's and they shot wide left about 3-4 inches and opened up to ~2.0-3.0moa! Had maybe 60-70 rounds through it without a proper cleaning at this point, but I'm wondering if the 105's may not have been stabilizing at 100 yards?

It's a 30" 1:8 twist, I figured this would be enough? 90 degrees out with a light wind at sea level, not sure if this makes a difference. Any help would be appreciated. Plan on going to the 300 yard line this weekend to do some more testing.

 

[boltman223]

They should be stable. And I wouldn't think the cleaning or lack of should be an issue. It is a factory savage barrel though so maybe I guess. I dont know if others have had issues or not with factory barrels.

Maybe after some more rounds down the pipe it will be better.

I'm curious how the factory barrels are throated too.

Did you go back to the 90's afterwards?

 

[Purcell429]

They should be stable. And I wouldn't think the cleaning or lack of should be an issue. It is a factory savage barrel though so maybe I guess. I dont know if others have had issues or not with factory barrels.

Maybe after some more rounds down the pipe it will be better.

I'm curious how the factory barrels are throated too.

Did you go back to the 90's afterwards?

Thanks for the reply. The gun had ~100 rounds through it when I bought it, but looked very clean through a scope when I picked it up.

I went back to the 90's for a few rounds and they went right where I pointed. Didn't put more than a few through as I figured the barrel might have been fouled.

 

[johara1]

If i were you i would check to make sure it is a 8 twist barrel. Plus you need to clean more and i would look at it with a bore scope. the other thing is why was it sold with a 100 rounds on it? Just maybe they knew it was bad....... jim

 

[RonAKA]

Hi all, new to 6br, picked up a Savage F Class and have only gotten in a session or two with it so far, but had a question about the 105 vs 90g Lapua ammo. Was able to do a quick sight in at 200 with both when I first got it with some success, then came back with a proper front rest to test at 100 yards last weekend. The 90's shot 4 3 shot groups: 0.26moa, 0.26, 0.27 and 0.29, plus a 5 shot group of 0.41, which I was pretty happy with.

Switched over to the 105's and they shot wide left about 3-4 inches and opened up to ~2.0-3.0moa! Had maybe 60-70 rounds through it without a proper cleaning at this point, but I'm wondering if the 105's may not have been stabilizing at 100 yards?

It's a 30" 1:8 twist, I figured this would be enough? 90 degrees out with a light wind at sea level, not sure if this makes a difference. Any help would be appreciated. Plan on going to the 300 yard line this weekend to do some more testing.

Nice gun by the way. I think it is the best off the shelf Savage that they make. I have the Savage LRPV in 6BR 12 twist, and sure envy the F Class stock...

You should check the twist, but I am pretty sure Savage only made the F-Class model in 8 twist.

You do not mention ogive to the lands position. Did you adjust the seating depth for the two bullets to get the same distance from or into the lands? My gun shoots best 5-10 thou jammed.

Based on Berger twist data and an assumed overall length of the Lapua 105 of 1.250" you may be marginal on twist for the 105, but should be just fine with the 90 grain at sea level. I see Berger recommend 7 twist for their 1.256" long hybrid, but 8 twist for the 1.222" VLD Target. I would suggest using the Berger twist tool with your best measurments of the Lapua bullet to see what you get for stability with a 8 twist. There is also the Kolbe Twist Rate Calculator to try also.

 

[Purcell429]

Thanks for the response! It is an 8 twist, as that is the only barrel offered, but I have not confirmed this (not sure how either!).

This is all factory loaded ammo, have to shoot through the ammo before I start reloading. Interesting about the Bergers, will have to check which ones I picked up recently, I think it was the Hunting 105, none of which call for more than a 8 twist.

I'm planning on trying out some 600 and 1000 yard shooting with some heavier bullets, any recommendations for what might work best in a 8 twist?

Thanks for the links to the twist tool calculators, this will be useful.

Nice gun by the way. I think it is the best off the shelf Savage that they make. I have the Savage LRPV in 6BR 12 twist, and sure envy the F Class stock...

You should check the twist, but I am pretty sure Savage only made the F-Class model in 8 twist.

You do not mention ogive to the lands position. Did you adjust the seating depth for the two bullets to get the same distance from or into the lands? My gun shoots best 5-10 thou jammed.

Based on Berger twist data and an assumed overall length of the Lapua 105 of 1.250" you may be marginal on twist for the 105, but should be just fine with the 90 grain at sea level. I see Berger recommend 7 twist for their 1.256" long hybrid, but 8 twist for the 1.222" VLD Target. I would suggest using the Berger twist tool with your best measurments of the Lapua bullet to see what you get for stability with a 8 twist. There is also the Kolbe Twist Rate Calculator to try also.

 

[knguyen]

Thanks for the response! It is an 8 twist, as that is the only barrel offered, but I have not confirmed this (not sure how either!).

This is all factory loaded ammo, have to shoot through the ammo before I start reloading. Interesting about the Bergers, will have to check which ones I picked up recently, I think it was the Hunting 105, none of which call for more than a 8 twist.

I'm planning on trying out some 600 and 1000 yard shooting with some heavier bullets, any recommendations for what might work best in a 8 twist?

Thanks for the links to the twist tool calculators, this will be useful.

i have had this same rifle you have now: 30 inch 1:8 twsit. this rifle is what go me into all sorts of trouble
got me hooked to shooting . this rifle will shoot the berget 105 VLD really well, just load up with some varget:
i was able to load up to only about 28.3 gr varget jammed 0.010, and it shot lights out at 100. Run light neck tension with it
with my rifle if i pushed anywhere higher beyond or near 29 gr i got bolt issues.
i can tell you that this rifle will shoot berger 105 VLD (hunting or target version of this bullet really well)
reload it and try again.
for 600 yards, the 105 will shoot much better then the lighter bullets
have fun with this rifle.
also as you know this rifle shoots much better when it has been had some shots thru it. do not clean this rifle during a match, trust me, it will shoot well up to 80-100 rounds before you have to do good cleaning.
good luck
khanh

 

[RonAKA]

Thanks for the response! It is an 8 twist, as that is the only barrel offered, but I have not confirmed this (not sure how either!).

I'm planning on trying out some 600 and 1000 yard shooting with some heavier bullets, any recommendations for what might work best in a 8 twist?

To check your twist, just start a cleaning rod with a snug fitting brush just past the throat. Mark the rod at the top and measure the amount the rod is sticking out of the gun. Push the rod in allowing it to turn with the twist. On your barrel you should be able to let it rotate 3 full turns. Measure the rod length again and divide the change in length by 3. That will be the length of twist in your gun. You may have to repeat it a few times to be sure you got it right.

On the Berger Quick Reference Chart check the G7 Form Factor column. The lower the Form Factor, at least in theory, the better the long range performance. The lowest choice in 6mm is the 105 grain Hybrid which requires a 7 twist according to Berger. The second lowest is the 105 grain VLD which requires the 8 twist. So you should be good to go on the 105 VLD which has a G7 drag coefficient of 0.265 (higher is better for drag).

You may be able to shoot the 105 Hybrid but it would require further checking using the Twist Rate Calculator. You should select this bullet from the list, enter your twist rate of 8, and your expected muzzle velocity, elevation, and temperature for shooting. It will come back with a stability rating, and if applicable how much the drag coefficient is degraded. Without any degrade this bullet is rated at 0.275. For example I entered an 8 twist, muzzle velocity of 2800 (which might be optimistic...), an elevation of 2000 feet, and a temperature of 75 degrees. It came back with a SG of 1.55 which is good, and with no degradation to the drag factor. However if elevation is at sea level, it says SG is marginal at 1.44, and the drag coefficient is reduced by 2% to 0.270. That is still better than the 105 VLD at 0.265.

My conclusion is that both of these bullets would be worth a try for the longer distances.

 

[dkhunt14]

The 105 will shoot good and be stable with an 8 twist. The Hybrid would not shoot good at distance in my 8 twist. Lots of others say the same thing. Matt

 

[cs700]

I have the same rifle & mine loves the 105 hybrids with RL15. 100 yards 5 shot group 1 hole. I tried the factory Lapua ammo & mine hated it.

 

[Nellej12]

My buddy and I have the same rifle, it was our 1st year shooting mid range. Both of us managed to get NRA ranked "Master" with these rifles at 600 yards. My likes varget at 30 grains and his likes RL15 at 32 grains, We both use 105 hybrids. Finding the best bullet seating depth will make a world of difference. Our 2 rifles like 2 totally different rounds.

 

[Shynloco]

Purcell429,
I have the Savage Model 12 6mmbr which also has a 1:8 twist barrel. I've had that rifle for something like 5 years and from day one (out of the box with nothing done to it and still today), for short distances like 100-200yds, my best bullet and powder have been 68 gr Barts Ultras (slightly better than Berger 68's) being pushed by VVN133 (mine tuned to 29.5 gr). For long distances you spoke of, go with the 105's (hybrids) and the powder will depend on what your rifles says she likes.

Alex

 

[FrankG]

A 1-8 twist should do it with no problems. Also as has been mentioned check the twist the best you can. Being a button barrel the twist rates can vary. You could have a non uniform twist (which is hard to check with the cleaning rod method) or you could have a barrel where the twist is a negative. Might start out at a 8 but gets slower as it goes down the barrel.

Later, Frank
Bartlein Barrels

 

[RonAKA]

Being a button barrel the twist rates can vary. You could have a non uniform twist (which is hard to check with the cleaning rod method) or you could have a barrel where the twist is a negative. Might start out at a 8 but gets slower as it goes down the barrel.

It would seem it should be easy to check with a cleaning rod method. A target barrel should have more than 3 turns in the barrel, so you can check distance traveled on each of the three turns and see if there is any variation in the three distances.