Laura needs a little help.....where do I start?

[tangiltows]

Hello fellow shooters, I have just been introduced to the 6BR cartridge and gees do I love it. I have been shooting the big bore stuff...7mm STW, 300 RUM and the monster 338 RUM and quiet frankly I'm tired of getting my butt kicked. Tho my 7mm STW is my favorite. My loads and shot groups are real good providing I can get over the anxiety of pulling the trigger. I now have a Savage 12 BR left load right eject SS 29" barrel 1:8 twist. Today was my first day shooting it. Talk about a relief from shooting the big 7 STW. Loved it!!! My first load was 107 SMK 29.4gr Varget, rem 7 1/2, lapua brass. It shot ok but I know I (the rifle) is capable of much more accuracy. I am not really interested in shooting the lighter weight bullets. I only shoot at 100yds now, but possibly farther in the future a longer range. I seat the bullets to kiss the lands. Data came out of the Sierra load book. What can I do now to improve? Am I off to a good start? Not ready to get into a custom rifle just yet. What is the next most simple step I can take? Unturned cases come out of the rifle .271. Suggestions? Advice? Many Thanks, Laura

 

[Kenny474]

Depending on how good the groups are, you are heading in the right direction. One thing I think would help is modifying your bullet seat depth a bit. I like to either go .010 into or .005 off the lands, as that will assure that all are either touching or off, basically because bullets vary a bit and just touching can mean some touching and others not.

You also didn't mention the type of dies or amount of neck tension you are using. I personally don't like to use more than .002" tension, and normally run .001 on my .222 bench rig. I like CCI BR primers as well, as they give me better ES/SD and accuracy than most others.


Below is a link to a case prep guide, you may find some useful info there.
http://www.6mmbr.com/jgcaseprep.html

This is a link to an article on ladder testing, this may also help you find the optimal load for your rifle as well.
http://www.6mmbr.com/laddertest.html

Good Luck, I'm sure others will have better advice than this to add shortly

Kenny

 

[johnmyers]

Laura,
I am also shooting 107SMK's and started just touching lands and worked deeper but just touching always worked best. Accuracy was good but not quite what I wanted. By accident I seated some at .010 jam and they shoot great!. 30.0gr Varget or 29.0gr H4895. Velocity in the low 2800's. Hope this helps.

 

[RonAKA]

What group sizes are you getting at 100 yards? In the testing I have done with lighter bullets in a 12 twist Savage, I get best accuracy at 0.010" jam. However seating depth can be bullet specific. If you are near maximum load you may want to back off some before trying a jam.

Also since you are shooting a short distance, having the last bit of velocity is not so important. So, using the ladder test as Kenny suggested is probably a good thing to do, to see which loads may work the best for your barrel length.

I have also found the barrel can like or dislike specific bullets, so you may want to try different ones. Berger makes some good stuff. There is also Lapua in the heavier weights. For primers you could try BR-4's and also the 450's to see if that makes a difference. Varget has worked well for me as a powder.

 

[tangiltows]

Thanks for all of your suggestions. I will try each of these of course not all at once, but at least now, I have a direction to go in. I will get onto working on this now so I can be ready for the range next weekend. Many Thanks, Laura

 

[Laurie]

Laura,

I agree with the various suggestions made - all good stuff, especially trying other bullets to find the model the barrel really likes. (There are small but significant differences in 6mm match bullet diameters between the various makes, so it is unusual to find a barrel that shoots everything equally well.)

So far as bullet seating depth / COAL goes, there is a possible issue in 'just touching' the rifling. All makes of bullet see slight variations in bearing section length, shoulder form etc between individual bullets in the box, hence variations in the position of the point on an individual bullet 'ogive' that touches the rifling. Sierra 107 SMKs have a reputation for having a LOT of production variation compared to some other makes. (You can batch them by length using callipers and a Hornady / Stoney-Point or Sinclair bullet comparator tool with a 6mm insert installed to measure the length from the bullet base to the 'ogive'.)

My 107s - old stock packaged in reinforced cardboard cartons - have significant variations in this measurement. The result is that if you set the seater die up to give you a COAL with the bullet 'just touching' with a bullet selected at random, some of your loaded rounds will be engaged well into the rifling, some just kissing as you desire, and a risk of some being marginally 'out', according to the varying shapes of the bullets as you take them out of the carton. Touching + not-touching in an ammunition lot does nothing at all for group size! Also, as you fire your first few hundred rounds, gradual erosion of the rifling 'leade' will make this situation worse if it initially applies at the margin, so a good-shooting load apparently 'goes off' for no obvious reason.

So you want to seat your bullets so that they are all either well 'out', nominally 0.015-.020" with this bullet if used without length sorting; or well 'in', a nominal 0.015" into the 'leade'. As lots of people have said, the 107 SMK is a very forgiving bullet, so going 'out' is probably a safer bet, especially if there is any chance of having to unload a live round in your type of shooting. This often leaves a 'jammed' bullet stuck in the rifling and the chamber / action / lug recesses full of powder grains. Believe me, you want to avoid this as cleaning every last kernel out is an onerous job since they stick like glue to any surface with gun oil on it, even more so bolt-grease!

Another thing to be aware of is that Savage barrels are very well made by mass manufacturing standards, but have a rough internal finish compared to a custom barrelmaker's products. So they usually take quite a lot of 'running in' before they give their best performance compared to a Bartlein, Krieger, Broughton, Pac-Nor etc. Most Savage PT, F, LRPV etc owners see a noticeable reduction in group size at around the 250 round mark.

Have fun, you should get good results with this set-up.

Laurie,
York, England

 

[Tozguy]

Laurie, Glad to hear that a Savage barrel will eventually start shooting after 250 rounds. That's where my F class 8 twist barrel is at now. Accuracy from the beginning has been disappointing.
Laura, I'm starting to have some doubts about using Savage's fast twist, long throated barrels at 100-200 yds. It is probably great for long distance shooting but the 95-105 gr VLD style bullets all seem to make lopsided holes in the target (as if they are canted) at these 'point blank' ranges. Have been trying some of the heaviest flat base bullets with some improvement but still nothing to get excited about. At least the holes in the target look straight with the flat based bullets.
My barrel gets fouled easily. Hopefully this will diminish with time and help accuracy.

 

[MGYSGT]

My Savage F Class is just breaking in. 300 rounds down the tube. Shot a .815 (edge to edge) at 300 yards last trip out. It started out at about 2" at that range. Now if Hornady would just make some more 105 AMax, I will be set. Guess I'll try some Bergers until then.