Help me with my 6mmBR!!

[BlackHawk95]

Hey guys. Ive got my gun running after a little downtime and had a new barrel and caliber chambered. Ive been fighting with this thing since day 1. The rifle is a Win M70 thats been blueprinted and trued. Barrel is a new Broughton 6mm 8 twist 5c barrel. The stock is also a Manners T4, tactical style.

So far ive tried two different powders, Varget and RE-15. on both powders Ive worked up loads from about 29.3gr untill the primers would show pressure. As far as bullets, Ive used 107MK, 105VLD, 105scenar. also tried the 95VLD and MK.

With either powder, the gun seems to preffer the 107MK or the 105 scenar. To date the best groups ive been able to get out of the gun are, with the 95VLD and 30.4gr re-15 jammed .020" it put 5 shots into .347". The other best was with the 107mk. 31.2g RE-15, it put 5 in .447"

At longer range. 270yards the best Ive managed with the 31.2gr re-15 and the 107MK it put 10 1.464"

I just can get any cosistancy.

I will say this, I had a bad barrel on this gunn befor the barrel I have now, and have been under alot of stress. Could I be just phycing myself out?

any ideas would be great

Jerid

 

[6BR]

Have you tried different primers yet? If not, try the CCI 450 or the Russian primers. Also what type of brass are you using? What type of dies are you using?

 

[pahog]

Just curious are you shooting fresh brass or fireformed brass?

 

[Twud]

I've good money that says don't jamb 'em jump 'em. Start at .020" and work forward. You'll likely see your best groups around 10

 

[wal]

BlackHawk95

If all your load development is shooting similar groups weather it be 29.5gr or 31.0gr and the groups look the same,and your not getting a coning effect) i will bet my bottom dollar that the muzzel hasn't been chopped back far enough. Have the muzzel air guaged or slugged chop the loose part off the muzzel and re crown. ,the end will be bigger ID from lapping tolerances)

wal

 

[Travelor]

I don't think you "problem" is a barrel one. Sounds like you have a good platefore for a 6mmBR and have done the right things to make it shoot. You did not mention if the gun had been bedded into the stock or not. If not have it "glass" bedded. I use Devcon and really like it.

We have 3 6mmBR's and one is rather finicky like yours. We eventualy ended up using 30.5 grains of VV550 and the 107 grain SMK loaded .020" jam and Wolf Small Rifle Magnum primers with neck tension of .002". I am assuming you are using Lapua cases. This particluar gun, like yours, just did not want to shoot enough VARGET to get the velocities up without excessive pressures. Might try this load.

The old "go to" load for 6mmBR is 30 grains of VARGET with a 107 SMK. Might try a harder primer,ie CCI or Magnum WOlf) and see if it will shoot.

Neck turning at this stage most liely will not help.

When you start getting groups in the .3's your technique becomes a LARGE part of target results.

 

[BlackHawk95]

6BR, Yes ive 4 different primers. CCI 450's BR4's, Fed small match. and wolf. Ive had the best luck with the Fed match primers. The wolfs were peirceing.

PAHOG, All the brass is fireformed Lapua brass.

TWUD, You may be right about jamming them. the farthest in ive seated any so far is .010" jammed

Wal, What exactly is the coning effect?

Travelor, The gun is pillar bedded. The only thing Ive changed on the stock is, the barrel was fully free-floated. I went in and put a pad about 1.5" long under the barrel and it seemed to help. Mine also seems to be not able to get enough Varget to gewt the velocitys up there. I think i should try the VV550.


Im going to let a friend shoot the gun today with a load of 30.0 RE-15 with a 105 scenar jammed .015" and a fed match primer. I want to see what kind of results he's getting.

I really do think its something phycological with me and this gun.

Let me ask one more question, i read somewhere if you line up your scope and dry fire and the crosshairs move, somethings loose? Right. Mine is doing that, but I cant find anything loose?

Thank you all,
Jerid

 

[wal]

BlackHawk95

Providing the rifle is put together properly and there hasn't been any built in pressure points it should be shooting tac holes. That why i believe your problem is your muzzel needs chopping and re crowning the last inch or two may be slightly larger in bore diametre.,lapping tolerances) this will allow pressure to pass the projectile at its most volitile point. ,Inconsistent grouping)
If this is the problem your groups will magnify even bigger at longer ranges. No matter what the load it will shoot a big round group and not cone in.
The coning effect im talking about is when you make powder adjustments 0.5gr increments you should get smaller groups. As your changing velocity and barrel node. When you get the barrel node correct the groups will indicate that,when you go past the load the the groups will get larger.,coning out)
Hard too explain over a keyboard.
Most scope reticles will move when dry firing caused by enursure from the firing pin. Dont worry about that.


wal

 

[BlackHawk95]

Wal, I got to looking at the chunk of barrel that was cut off. The barrel had, cut off 1.25" minimum. This one was cut back 1.75".

Where should I look for any pressure points? Do you think I should remove the bedding under the chamber to fully free-float the barrel and try that?

Im going to take a little while off shooting. I think Im just really stressed out over work lately and it affecting my shooting. But, when I do resume. Im going to try a few things and see what happens.

Also, Im hoping my friend gets to shoot the gun today. Im curious to what kind of results he gets.

Jerid

 

[MarkS]

BlackHawk95,

Sometimes the 3 screws on a Win Action can cause problems, check and adjust the middle screw, if needed.

Have you tried the 108 Bergers? Try them into a little and off 0.010".

One thing I do when working up loads. I shoot 3 shot groups starting out. Two more shots will not make the group any smaller. Shooting 5 shots text the shooter as much as the gun.

Are you shooting with wind flags? Very little wind can open a 0.2" to a 0.3" & 0.4".

Mark Schronce

 

[fdshuster]

BlackHawk95: Over the years, I've usually had problems trying to get boatails to group at 200 & less, while flatbase were always sub moa. Recently joined a local club that has a 300 yd. range, so am able to do a lot of comparisons there. Flatbase groups are opening up, and the boatails are becomming much smaller. Kevin Thomas from Sierra bullets, did an article in P.S. a while,long?) back, saying that in many instances, boatails will not really start to perform 'til 300 yds. and beyond. My "rule-of-thumb" now is: flatbase for 200 yds maximum, and boatails for 300 and beyond.

 

[BlackHawk95]

Thanks alot for all the tips. I really think its me just not shooting good right now. Today I shot a gun I usually shoot well and didnt shott that good at all.


I think im going to just not shoot for a while and them se what happens.

Jerid

 

[wal]

I would still have the muzzel checked by your gunsmith with and air guage or slug it your self.,be careful) Just to make sure.
If you have added bedding compond to your original bedding you may of built in a pressure point. Check to make sure your:
-barrel is free floating
-trigger is not touching stock or trigger gaurd
-including bolt release and safety
-Make sure your scope base screws are no going through and touching your bolt body.
-make sure your action screws are not touching bolt body.
-make sure bolt when closed is not touching stock.
-make sure your firing pin doesnt protrude to far this happens with SAKOS more commonly.
-make sure your firing pin assembly is clean including pin hole
,can effect lock timing)
-make sure case head has suffient clearance in bolt
-bed trigger guard and floor plate independently to your action bedding
I dont know how its been bedded but would suggest re bedding action and make sure theses principals are checked.
Good Luck

Wal

 

[Dave223]

Blackhawk, how heavy is the trigger?

Dave

 

[BlackHawk95]

Wal, the bedding in the rifle is very nicely done. When the barrel was changed from a lilja to the one currently on the gun. I got it back and was struggling with it and found the barrel was free-floated 100%. I went in an added a pad under the barrel about 1.5" long. and it shot better. It not a big deal to sand it down a tad, till its not touching again.

Dave, I dont have a trigger pull gauge. But. its a jewel factor set at 1lb thats been lightend slightly.


I really believe one of my biggest problems is in my rear bag. As I dont have a good one that I can get comfortable with. Its just a cheap Caldwell bag. When I really need something like a Protektor.

Jerid

 

[BlackHawk95]

I was talking with some guys yesterday that shoot a good many 600 yard benchrest matches, and I was aking them about technique, And I think that has the most to do with me not shooting well.

Im pretty much convinced my rear bag and how im using it is the major problem. Im going to get me a new bag and change a few more things about how I shoot and see what happens.

Thanks for all the help,

Jerid

 

[chino1969]

Try jumping your bullets from the lands. Start approx. .030 off the lands and go back by .010,further from the lands).

My 6mm 1 in 7.5" Kreiger just wasn't performing as I thought it should. I was shooting Berger 105 VLDs with Varget and just knew the rifle was capable of doing better. I contacted Eric Stecker of Berger and he told me to try jumping the bullets. Well, at .034 off the lands I found my sweet spot.

Lou Baccino
Chino69

 

[treeman]

,"Let me ask one more question, i read somewhere if you line up your scope and dry fire and the crosshairs move, somethings loose? Right. Mine is doing that, but I cant find anything loose?")
Blackhawk, If you dry fire the gun and it is on a rest ie "stable" and the cross hairs move there IS something loose. it may well be in the scope itself. I've had this problem before. I tooke a 223 on a prarrie dog hunt with a used scope that i had purchased at a gun shop and my spotter would say a foot high - afoot low. so we dry fired it and the cross hairs would jump up one time and down next time. could be you have a similar problem just on a lesser scale. hope this helps. if it is posible that you are flenching have some one load the gun some times with an emty shell and some times with a loaded round. if you are flenching it will be very obvious. hope this helps. ______treeman

 

[BlackHawk95]

Chino, I havent shot the gun much at all lately. I did get some 88gr Berger high BC FB bullets and tried them. They shot better than the boat tail bullets. My friend put 3 rounds in 1 hole from 100 yards.


Treeman. The reticle movement in my scope very small. maybe 1/4". Ive been looking at all my friends guns and everyone moves slightly when fired.


Yesterday I was shooting so rounds at 100 yards, and was not grouping all that well. I decided to adjust the trigger a little lighter, While doing that, somehow I noticed my front action screw was contacting the lug on the bolt. The action has always been tight, so Ive never thought about it. But I got to looking and sure enough, I have some marks on the lug where its rubbing. So, I cut a few threads off the screw and shot my last 6 shots. My last 3 where a nice little .250" triangle.

Im going to have to load some more up and see what happens.

Jerid

 

[BlackHawk95]

Well, I had some spare time this weekend and decided to start over with load development with the 107MK. I uniformed all my brass and used Fed match primers and RE-15 powder. I started at with the bullet .005" jumped and 30gr powder working in .2gr up to 31.2gr. Well It didnt start off to well, but once I got around 30.8gr it started shooting tighter, and 31gr was the best. so, I started the test over again with 31gr RE-15 but played with the seating depth. I started at .015" jumped and worked my way in .005" increments to .005" jammed. It really started to shoot better. So I tried .010" jammed and with 31gr of powder and it put 4 in one hole and one more just outside. This is at 100 yards. Im thinking about going another .005" further out to see what happens.

What seems odd is it seems to like more powder than Ive seen for other people. And the fact that it shoots the 107MK better jammed. Its a Broughton 5c barrel. MAybey the canted lands like that combination.

Im definately going to go back and try the 95gr MK's and start at 31gr and go up to 32gr Re-15 and see what happens.

Jerid