SSS Inc's 117 gr 6mm bullet,Goliath)

[rcw3]

Today I received some samples of Superior Shooting's new 117 gr 6mm bullet. The 117 gr bullet looks great, but it's a real Goliath for a 6mm projectile. When I did some checking on how the bullet sits in relation to the throating of various 6mm's, it looks like you need about .050" - .060" more free bore than you need with a DTAC 115 to keep the junction of the boat tail and bearing surface in the same place, and about .125" - .135" more free bore than you need with a Sierra 107 to keep the junction of the boat tail and bearing surface in the same place. I will try these in a 6XC,after I throat out one of my barrels a bit) but the bullet looks big for a 6XC case. I am also looking forward to trying these in the 6mm Super X, the 6CM, and the 6mm Remington I have, all of which have a good bit more powder capacity to enable the use of slower powders,H4831SC, H1000, etc.) with such a bullet.

If these shoot as well as they look, the 6mm's may give a 6.5 x284 some real competition at long range - we'll see!

Attached is a picture with a boron nitride coated 117 gr bullet,left) vs a moly 115 gr DTAC,center) vs a moly 107 Sierra,right).

The 117 gr is 1.376" long, the 115 DTAC is 1.290" long, and the 107 Sierra is 1.225" long.

David Tubb is to be congratulated for bringing this offering to the market.

Robert Whitley

 

[Hoser]

Is it gonna take a 1-7.5 or 1-7 to stabilize it?

 

[rcw3]

I followed up with David Tubb on barrel twist and he says with the 117's he has been shooting 7.5" twist barrels. Just from personal experience, I would be wary of 1:7" twist barrels in 6mm. I know of three different people,myself included) who tried a 1:7" twist barrel, only to find that the extra twist made pressures spike so you could not get good velocities without high pressures.

Robert Whitley

 

[Turk1961]

Well now what am I going to do with the Pac-Nor 7 twist I have on order?

Hanging around here, Benchrest and other like sites for over a year. Reading and learning about 6mms. Make a decision to buy a bull 6mm to get started. And it is wrong! Now what?

Think I will go back to my 10/22s. Anyone want to buy a nice SS Pac-Nor barrel in about two months?

 

[rcw3]

Well now what am I going to do with the Pac-Nor 7 twist I have on order?

Hanging around here, Benchrest and other like sites for over a year. Reading and learning about 6mms. Make a decision to buy a bull 6mm to get started. And it is wrong! Now what?

Think I will go back to my 10/22s. Anyone want to buy a nice SS Pac-Nor barrel in about two months?

Maybe call them up and change the twist before they make it - I have done that in the past.

Robert Whitley

 

[Longshot]

I followed up with David Tubb on barrel twist and he says with the 117's he has been shooting 7.5" twist barrels. Just from personal experience, I would be wary of 1:7" twist barrels in 6mm. I know of three different people,myself included) who tried a 1:7" twist barrel, only to find that the extra twist made pressures spike so you could not get good velocities without high pressures.

Robert Whitley

Which only raises the question, "Is there really any point in such heavy 6mm projectiles?" Sounds to me like we're approaching a sort "coffin corner" in terms of velocity, stability, and projectile failure. This is just an opinion, but I rather doubt the theoretical gains in BC are worth the trouble.

Regards,
Bert

 

[Forum Boss]

Keep in mind that Robert's experience is his own and David Tubb has shot 7-twist barrels with success, and they seem to work quite well in .223 Calibers. David has experimented with polygonal rifling and that may make a difference. Polygonal rifling and canted land rifling seems to stress bullets less and seal gasses in a different fashion.

Also, Berger's research suggests that barrel length may make a difference--that longer barrels,30" vs. 27-28") produce more heat and heat creates problems for bullets.

My point is simply that we don't have conclusive evidence that a 7-twist won't work for a 6mm. And keep in mind that David feels a 7.5-twist will work with the 117s.

 

[reverend]

I shot a limited number, 10 )of the new Boron nitride coated 117 DTAC's today through a 28 " 7 1/2 twist Schneider polygonal barrel.

Conditions were awful, cold and very windy. Seating of the bullet certainly wasn't ideal. Even with the bullet jammed 0.020" into the lands the base was way back in the case.

Results were very good. Velocity was 3150 fps. No pressure signs. Both 5 shot groups were under 1/4 " at 100 yds. These groups were shot from a clean cold bore.

Hopefully the weather will be better tomorrow and I'll try some more.

I think David may have delivered a spectacular product.

John

 

[Ronald]

rcw3, Do you think these new 117gr DTACs will shoot good out of a 243 Win. with a 28" schneider 7.5 twist barrel? What overall lenght of the loaded 243Win with the 117gr do you think will be needed for optimal results?
Thanks
Ron

 

[reverend]

I shot them from a 6 X 47 Lapua.

My Tubb gun in 6XC needed a little work, I just got it back. I hope to get it put back together tonight and try these 117 DTAC's in conjunction with the latest Norma 6XC brass tomorrow.

In my experience the samples of the new bass I received will take as much pressure as the lapua brass and has tighter tolerances. I feel it is superior to the lapua brass.

I expect with the slightly larger case of the XC I will be able to achieve a little higher velocity, but I don't know, I'll have to give it a try.

And yes, it should give spectacular ballistics at that velocity.

John

 

[Turk1961]

Too late to change my order. It is in a group buy.

I will try it with a 6mm Rem and maybe it will work OK.

It will end up at 26" and that may help too.

 

[rcw3]

I installed a 30" 6XC chambered Schneider 7.5" twist polygon barrel to a single shot tube gun this morning for some chrono testing. This barrel is chambered with the recent version of the 6XC reamer with a 3/4 degree throat angle and a .123 freebore. I did not throat out the barrel specifically for these 117 gr bullets, so the bearing surface of the bullets sat back in the case a little bit.

The chrono results with the boron nitride coated SSS 117 gr 6mm bullets are as follows:

Win Cases,1x Fired), BR-2 Primer, .015" jump

38 gr H4350 - 2846 fps,E.S. 16 & S.D. 6) Moderate Loading
39 gr H4350 - 2922 fps,E.S. 33 & S.D. 12) Pressure Signs Evident
40 gr H4350 - 2993 fps,E.S. 16 & S.D. 5) Very Hot Load

Norma Brass,New - Latest Batch), BR-2 Primer, .015" jump

38 gr H4350 - 2856 fps,E.S. 12 & S.D. 5) Moderate Loading
39 gr H4350 - 2921 fps,E.S. 28 & S.D. 12) Pressure Signs Evident


I did not do any accuracy testing. I will not shoot the 40 gr load because the brass flow into the ejector area was substantial and the primers were very flat. In truth, the 39 gr load is getting pretty warm and with both the Norma Brass and the Winchester Brass, the E.S. & S.D. numbers also went up with the 39 gr. loading.

Robert Whitley

 

[Forum Boss]

Based on Robert's testing, Jason Baney's testing with 115s, and what David Tubb has told us, I think Reverend's velocity results for the 117s are anomolous. He's probably got a super-fast barrel, but I suspect his chronograph is reading on the high side--way high. I don't think we can expect this bullet to go much past 3050 fps with the 6XC or 6-6.5x47 class of cases, and even 3000 may be hard to achieve for some people--this was certainly true with the 115s in 6XC brass. Every barrel is different however.

But I'm one to "never say never". Maybe boron 117s can do 3100. I'm glad folks are out there testing. When we did our rail-gun test, Jackie Schmidt was able to drive the 105 Bergers at 3000 fps from a standard 6BR and he was loading his cases a dozen times or more. That did surprise me. Other guys weren't able to duplicate that but I know Jackie was hitting those numbers,which were confirmed with three different chronos).

I would be interested if Reverend could borrow another chron and re-test. We've seen variances of up to 90 fps among Shooting Chronies, and 30-40 fps among same-model Oehler 35s.

 

[reverend]

It's possible my chronograph reads high, it seems most of my loads have greater velocity than other posts. I don't think I am the only one getting these speeds though. The following reply I received from David Tubb today in response to some questions I had for him.


John,
You will need to throat your rifle about .040" longer than for a 115 DTAC to keep the neck shoulder junction in front of the case -
On a 6XC the OAL of the loaded round should be greater than 2.810" to be in front of the donut
I have some new 6XC reamers on order, I sent the one I had for my testing to McMillan so they could start chambering).
I am getting a throating reamer made that will be like a chambering reamer so that I can send it out and one can throat their own barrel to correct depth with out deepening the chamber.
You can buy a 28" barrel from us as soon as we get the reamer in.
My other knee is doing well,2 weeks now)- thanks for asking.

If you post something on 6BR - do give them the velocity you are driving the bullet.
I also am able to shoot the 117 at 3120fps in my T2K in a 29" barrel and reloadable brass,primer pocket is still tight after 5 firings)

Regards
David

 

[rcw3]

I always dislike getting into the velocity discussion. It always seems there are those out there that get 100+ fps more velocity out of the same cartridges that I shoot. Anymore I just disregard velocity claims and run off the actual chrono tapes I get from a chrono I have that I know is accurate. I also put my screens as far away from my rifle and the printer as the wires will allow because I feel you get the best and most accrate readings there,i.e. muzzle blast does not interfere with your readings). If I believed many of the velocity claims,David Tubb included) then I must have had the consistent bad luck of getting every slow rifle barrel that barrel manufacturers produce.

The key number for me anyway is the consistently accurate top velocity - not just top velocity and have a reloadable brass case - not just a top velocity you get an accurate group from one day but its over the top the next day - but a top velocity you can count on and shoot day in and day out, in hot, cold and various weather conditions and have great accuracy all the time. Personally, I suspect that velocity number is typically more conservative than most want to admit.

Robert Whitley

 

[reverend]

I agree consistent accuracy is the most important factor. I also think that if my velocity readings are consistently high the most likely reason is that my chronograph reads high.

I have no idea if this is the most accurate load, too early to tell.

I also think there are many unexplained variables. I have 3 rifles chambered in 6 X 47 Lapua. they are all chambered with the same reamer, all have the same type barrel in slightly different lengths. They all have different actions. In the same lot of powder there can be a 2 grain difference between rifles in what is a hot load. One of my rifles shoots consistently faster and better than the others. It has had two different barrels.

I tested the bullets in my rifle that shoots the fastest. I also stuffed 40.9 grains of H4350 into the cases. I don't recommend anyone else do that. I had easy extraction, no brass flow, but the primers, CCI 450's were somewhat flattened. I usually only neck size my brass, and that is what I've done with these cases. When I reloaded these cases the primer pockets were still tight, and the round slides easily into my chamber. In one of my other rifles I would have blown the primers out with that load.

I've just used the last of my previous lot of H4350. Things will probably change again.

Just observations, not science.

John

 

[rcw3]

John

One thing is for sure with that Lapua 6.5 x 47 brass,I assume you necked it down to 6mm), you practically have to blow up your gun before the primer pockets loosen and you get brass flow, at least that was my experience with it - great stuff!

Different rifles, in my opinion, handle pressures better than others as well. I am shooting a Remington 700 Tube Gun. That rifle has a plunger ejector,they are larger in dimeter than some other different makers actions I have seen) and brass flow shows up earlier with such an action, and the bolt lift gets sticky. The Barnard action I have has no ejector and a very smooth full support bolt face, and that shows almost no case pressure signs, and never seems to have hard bolt lift, no matter what you do, and it's wierd because you can take a load right up and "over the top" and not know it,although the "over the top" loads will shoot poorly and if you try the load over a chrono you would say - "whoa, no wonder it does not shoot"

I know there's a great variance in chronos too. When I was at the range about 6 months ago a guy set up his chrono and shot his 223 service rifle,20" barrel) through it with a 600 yard 80 gr Sierra load,24 gr RL 15). He said his bullets were going right around 2850 fps and that's what his chrono showed. I told him there was something not right there and that was way too fast. After I set up my chrono, we ran 5 shots from his rifle across my screens and the load came out around 2725 fps which seemed about right especially considering his come ups. Is my chrono slow, I don't think so, but I have seen others that register a good bit faster than mine.

Robert Whitley

 

[Rob01]

What is this boron nitride coating? Never heard of it. Advantages? Disadvantages? Is it supposed to be like moly?

 

[jb1000br]

Rob, sheesh, you been under a rock!!

Look at the last Blog entry...

Yep, s'posed to be better than moly...

JB

 

[reverend]

OK, shot some more Boron Nitride coated 117 DTAC's today. Shot in a Tubb Spectacular, 30" Schneider 7 1/2" tube. Barrel has previously had about 3000 rounds through it, I thought it was done. Some good groups, some not so good. I'll attach them below.

4 groups of 5 shots at 100 yds. 1st string averaged 3060 fps. No pressure signs on the Norma Brass, latest batch. Chrono didn't survive the second string. I think I'll go shopping tomorrow.

It was once again windy today, gusty 10 to 15 mph. These groups were good for my shooting ability, not sure I could do much better than the good groups. Shot off a Harris bipod with a rear sandbag.

I think you could get more velocity out of this combination, probably more accuracy. Could still fine tune the load. I'll have to wait for the 117 DTAC's to be released to do much more testing, I'm running out of samples. I'm anxious to try them at distance.

I still feel this is going to be a spectacular combination.

John