.134 freebore,can i crank it some?

[chris308]

Hi there,my current rig is a 6br with a .134 freebore. This seats the jlk and berger 105`s with the boat tail right at the nech/shoulder junction. A sierra 107 just a tad deeper.
After doing alot of reasearch on this forum I have concluded that 30.0 grs of varget is the "classic" accuracy/start load. The rifles that seem to like this have about .060 freebore such as my last barrel.
With my longer freebore,can i venture into the 31.0+ gras of varget?
The only testing i have done so far was with vv n150. 30.7 grs with a sierra 107 showed promise but shot a 9" 5 shot group with 31.3 grs with a jlk 105.
With these loads the primers were still pretty rounded,no cratering,no pressure signs at all.
Was thinking i could get 32.0 grs of 150 and a little over 31.0 grs of varget with my freebore...what do you folks think?
chris

 

[Preacher]

That seems like a lot of freebore for the 105-107's, but it will allow a bit more powder room. Have you considered giving RL-15 a try, it might suprise you.....

 

[Cheaha]

Mine loves Vit.N-550 w/ 105gr Moly Coated A-Max's.Getting 2912 fps out of my 26" bbl.

 

[Preacher]

I was just thinking that if my .110 freebore in the Green rifle only had the bullet part way into the neck that a longer freebore would make that even less if your into the rifling at all.
The Green rifle don't seem to mind being out that far, but I think that being further into the case the bullet would have a better chance of being straight.
Don't forget I'm new at this 6br stuff, but not new in general, and always willing to learn.
I have always set my normal varmint and deer rifle chambers up so the base of the bullet was to the base of the neck shoulder junction and .020 off the rifling, and just got on to shooting, but this 6br stuff is a different story.
Shouldn't the freebore match the bullet you would use the most, and still have the optimum hold on the bullet ??

 

[expiper]

My cave man theory on the FB,leade) is that if it is .080" or more ..,many long range cals are .135-.188") the long cylindrical leade which is .0005",usually) bigger than a bullet...the bullet is pioleted in this strait cylinder and even if the ammo is bowed like a bannanna,sp-?-hah)things will get straigntned out by the chamber!!!! and the bullet will be pioleted straight into the throat area and down the bore..Roger

 

[Preacher]

I checked out a few 6br's that were out close to .005 in a chamber that according to the fired brass is perfect with no run out. They did not straighten out when chambered in the rifle, and that was with a .023 jam... and the bullet was only about a 1/3 into the neck, so if it was going to straighten out it seems like it would have.....
Am I missing something here ????

 

[expiper]

Brass has spring-bak...the bullet was piloted strait when in the chamber!!think about it.....

 

[Preacher]

I never gave the spring back thing a thought, but I can believe that could happen.
This will give me another project to try.
I'll find 5 crooked ones and compare them to 5 straight ones and see what happens....
Stay tuned...

 

[Preacher]

Well, the run out test seems to lead me to believe that the chamber don't really help straighten a crooked bullet out as much as some would have me believe.

I trust the Green rifle enough to know it don't like crooked bullets very much....

I couldn't find 5 that were off enough to test so I only shot 3 of each and the results should speak for themselves....
Some folks may not mind 100 yard 4's, but I sure do ..............

 

[chris308]

With a Jlk 105, the pressure ring is about 1/3 the way in. Re 15 is next on my list. I started out with vv n150,which worked great in my last br). Was suprised to get pressure signs at 31.8grs. This would be hard bolt lift and cratering of primers. This is with a bushed firing pin.
This freebore is perfect for the 107/108`s,still has some boat tail in the shoulder area. My idea for a long b.t. is to fill the powder to the base of the neck and still have the boat tail out of the way,??)
Preacher, I will be doing re15 next after seeing your results. Would you say 30.7 as a starting load? Am thinking i should get close to your results with my long freebore.

 

[chris308]

Lynn,
Thanks for responding. I have a 28" kreiger on this thing. At 30.7 grs of n-150 and a 107 SMK i got 2860fps. Keep in mind that my chronograph is a shooting chrony and shifts depending on were the sun is.

My whole idea behind the long f.b. is to get the boattail well out of the shoulder and use a slower powder. My last barrel, which seated the 107 well into the shoulder loved 150 and filled the case well.

Recently I used a jlk 105 with 31.0 grs of n150 at 1000 yards. Morning relay,5 shots) I put 3 under an inch and the last 2 slipped out to open it to 10". I took the target around to the more experienced shooters and they seemed to think this was no fluke and I stumbled onto something good. Whether it was a fluke or not I`ll never know but my 2 "flyers" slipped out in the same place as everyone elses. Afternoon relay i held 5 shots at 7" which i thought was good considering horrible conditions,many dq`s, and all the magnums shot about the same as myself. This load was never shot on paper at close range or chrony`d.

31.8 grs of n150 was max for this gun.Hard bolt lift,cratered primers and bad accuracy at 1k. I was suprised at this as I would have thought that I could get 32.0+ grs of n150 with this f.b. This is with the firing pin bushed,GRE-TAN)

I was considering 4350 next for sure....thankyou for all responses..I`ll keep you posted chris

 

[chris308]

Lynn,
thanks again for the input. You have helped me out in the past with my br`s. I`m going to play with the n 150/jlk thing for a bit.
I`ll go along with your prediction. Either a br or a dasher for that record.
My 3 shot group under an inch at 1000 yds really got me thinking. Again this could be a fluke but very promising.

putting the chrony in a tube is an interesting idea but i think santa will be bringing me a ced chronograph soon. Any chance you could go into detail on your idea?,about the tube) This just got me very curious.

while we`re talking chronographs, I always thought mine,shooting chony) gave slow data. I could never duplicate the speeds i read here,ever on ANY of my stuff
thanks again

 

[chris308]

Lynn,
After doing some thinking, I ordered a 30", 1.250, 6mm barrel for my sleeved 700. This gun weighs in at about 20lbs. This was my slow twist br set up. Am wanting to try this for heavy gun off and on in the 08 season and see what happens. Will keep you posted.
I found a couple of 100lbs chlorine buckets here at work for the swimming pool. These should be perfect to fit my shooting chrony in. White plastic,somewhat seethrough and light. will try your tube idea and see what happens.
chris