6mm 115grain Berger & Dtac, any good?

[Mudcat]

Shoot, I know some folks that do nothing more than load up their 80s in their 223 AR15 to the max, actually, OVER the max, and use them at 600 having never determined just how good they do shoot. For them, velocity wins over accuracy as they are looking to make up for lack of skill...ie wind readin'

John

 

[Kabang]

If you have crapy accuracy, how can you learn wind reading? You are all over the place and have no frame of reference.

 

[rcw3]

If you have crapy accuracy, how can you learn wind reading? You are all over the place and have no frame of reference.

Dittos to that statement!

Robert Whitley

 

[Mudcat]

If you have crapy accuracy, how can you learn wind reading? You are all over the place and have no frame of reference.

Dittos to that statement!

Robert Whitley

And, to add to that, if you cant hold at least the 10 ring for 22 shots, how will you learn to read the wind?! I watch folks at every match, even reduced course, dial in, shoot a couple center shots, then boink a 9 at 11, then watch them click right and down and shoot a 9 at 5 and wonder what the heck is going on...one day, they will figure it out.

John

 

[JRinCo]

115 gr. Bergers: What barrel twist do they really like, 1 in 7.5 or 1 in 8

 

[GermanS1]

JR, the 1:7.5" twist works very well for me in the 6XC, for a 6BR I would probably use a 1:7" twist,but I don't plan to use them in 6BR). I don't know of anyone who's gotten them to work in a 1:8", including in a .243, but that doesn't mean there isn't someone, somewhere,or maybe a lot of someones) who makes it work - but I haven't seen it.

 

[Mudcat]

I will probably have the answer to the 1/8 question tomorrow as I plan on testing the new 115 thicks in a T2k with a Wilson 1/8 26 inch bbl.

Will report my results.

John

 

[spclark]

I've run the DTAC's in 1:7.5 twist PacNors & 1:7.8 Bartlein. No grief at all.

The 115 Bergers I put thru a 1:8 Schneider,polygonal) saw me losing bullets down range, so I stopped. I tried them late last year in the Bartlein & they made it to 600 yards, but I hadn't worked up the right load & accuracy was awful in a gun that shoots the DTAC's exceptionally well.

I may try the Berger 115 THICK but it'll be awhile as I have lots of the DTACs now on my shelf. Every other 6mm Berger I've shot works great.

 

[rcw3]

JR, the 1:7.5" twist works very well for me in the 6XC, for a 6BR I would probably use a 1:7" twist,but I don't plan to use them in 6BR). I don't know of anyone who's gotten them to work in a 1:8", including in a .243, but that doesn't mean there isn't someone, somewhere,or maybe a lot of someones) who makes it work - but I haven't seen it.

German

A 1:7" twist is no good for an 6mm - the twist is just too tight - more like a wall than a ramp for the bullets - you will likely see a lot of pressure, even with mild loads,been there, tried that, and sitting now on two 1:7" twist 6mm barrels that I consider junk). The 1:7.5" twist barrels work for 6mm's but in my opinion that's where the edge of the point of no return is, step over it and go tighter and you are inviting problems.

For the 115 DTAC's and the 115 Berger I have used a 1:7.8" twist with great results. In summer conditions and a cartridge that can deliver 2750+ fps or so with a 6mm 115, a true 1:8" twist will stabilize both, but once again, you are right on the edge, go any looser and you are inviting problems.

Probably the best all around twist for the 115's is a 1:7.75" twist.

Robert Whitley

 

[1shot]

Robert is exactly right. I'm currently shooting his cartridge design the 6mmSuper X. It's a 30deg. shoulder 243 with a slightly longer neck, and I have two 30" barrels chambered for this cartridge. Barrel #1 is a Krieger 4 groove .237 bore; 1-7.75" twist. It will shoot the 115 VLD bullets all day at over 3,000 fps. and never flinch. Barrel #2 is a Broughton, .2365 bore, 1-8" twist. It will shoot the VLD bullets OK, but you need to really drive them hard. However using the DTAC's or 105 VLD's it will routinely keep 5 rounds in .2 to .3 moa. Either barrel is a hammer, but as Robert said, you need know the true twist rate of your barrel and use the appropriate bullet for it.
I hope this helps,
Lloyd

 

[spclark]

Anything to be gained,pun intended) by using a gain-twist barrel?

They've been getting a lot of positive results in bench rest recently. Certainly may reduce that "wall" effect when trying to use something tighter than 1:7.5.

 

[rcw3]

Anything to be gained,pun intended) by using a gain-twist barrel?

They've been getting a lot of positive results in bench rest recently. Certainly may reduce that "wall" effect when trying to use something tighter than 1:7.5.

I think that would be one way around the issue, but truly you really don't need a twist faster than a 1:7.5" anyway for the 115's. If I were going to do such a gain twist for the 115's, I would begin at the breech around 1:8.5" twist and wind up at the muzzle at 1:7.5" twist.

I am currently testing one,a Bartlein "Transitional Rifling" barrel) in one of my 6mmAR Turbo 40 Imp. uppers. It starts at 1:9" twist at the breech and ends at 1:8" twist at the muzzle,I did not set it up to shoot the 115's, only the 105-108 gr bullets max that's why I ended up at the muzzle with a 1:8" twist).

Robert Whitley

 

[HPMike800]

An f-class shooter here rechambered a 1:8tw 6BR to a 6superX to shoot 115's. He reported good results at 600 and poor results at 1,000. The jury is still out as it was day one, but, it did not sound good.

Robert:
Have you shot the gaintwist barrel enough to have an opinion? It's always been idea I've had a hard time accepting especially for long bullets.

Mike

 

[Mudcat]

Shot 2 strings at 300 yards yesterday out of a very worn Wilson 1/8 twist bbl,on a T2k) and the Berger 115 thicks all made the target, all went in straight and were grouped well for a toasted bbl and I was running them at 3100 fps,maxed out H4350 load this time, no bullet failures).

Thats almost 200 bullets at 3100fps or more and ZERO failures. I think its time to develop a load for 600 yard use this season....new bbl going my "big course" T2k before next weekend.

John

 

[rcw3]

Mudcat

Great testing but it is unlikely you will wind up with a load that will be consistently accurate for 22+ shots in a row with the 115 gr 6mm Bergers at 3100 fps - - - at 2950 fps, yes - - - but 3100 fps would be most unlikely.

I run into this all the time with guys trying to beat a 6.5 x 284 with the 6mm Super X and just try to run things beyond their accurate limit. The Super X can easily run the 115's at 3100 fps, but it seems just about impossible to get the 6mm 115's to stay consistently accurate at that velocity,for 22 or more shots in a row). If you are going to shoot a few sighters and then a 5 or 10 shot group you might pull it off, but not 22 or more shots in a row, and not match after match after match.

Robert Whitley

 

[Mudcat]

I am probably looking at 2950-3000fps with the load of H4350 that I am going to use. WHile I have Re17, I am not sold on it yet and am not about to start a season with it only to find out I need to change out, so H4350 will be the ticket again this year. And 2950-3000fps with 115grs of VLD aint that shabby anyhow!

John

 

[rcw3]

John

I have RL17 too but I am really not using it for anything currently,plenty of speed in RL 17 but not the easiest powder to find consistent accuracy with, and low ES and SD numbers seem harder to come by with that powder too - learned a lesson working with RL 17 that a good target accuracy powder is not all about speed, it's about the proper balance of all the important factors that make a powder good).

On another issue, I am not not trying to "toot my horn", but this past year I shot more cleans than not at 600 yards shooting the 115 gr 6mm Bergers in the range of 2925 - 2950 fps, and at that speed you are still very close in performance to a 6.5 x 284, but with a very low recoil factor and much better barrel life. As I read forum postings, it just seems people can just not stop gravitating to trying to push the 115's up at ridiculous velocities, then they cannot understand why they are having trouble getting consistent accuracy,then blame it on the gun, the barrel, the cartridge, the bullets, whatever). You wonder if people realize that there are practical working limits for certain things. If you could consistently and accurately run the 115's at 3100 fps, you would see a lot more shooters shooting them and winning long range matches. I think the 115's have a somewhat tarnished reputation, not because they are bad, but because shooters expect or try to get too much from them,i.e. usually beyond their practical working limit, especially by pushing the velocities way up and out of the "sweet spot").

Robert Whitley

 

[mikecockcroft]

Roberts posts always seem to make sense.

 

[GermanS1]

Robert, I agree completely with what you wrote. While I did the initial testing of RL17 to find out what it would do, I've stuck to my load of 4831sc,2930 fps) for match use so far. Last week at our 1000 yard state championship, the 115 Bergers with 4831sc worked just fine,195-9, 200-9, 199-8 all irons) even though I got in a hurry on the first string and blew a few shots. We had a sudden and severe hail storm that caused us to cancel the match before the last string. The week before, shooting the same load I had a 198-7, 197-7 and 198-10, also all irons and in windier conditions. I'm more than a little reluctant to give up very good, very consistent accuracy for more velocity. The 4831sc load holds great elevation, the rest is up to me; that's how I see rifle matches.

 

[LenBackus]

Forgive the ignorance of a non-competitor. Is the problem with 22 shot string accuracy or blowups,vs shorter strings) related to barrels heating up or fouling...or to something else?