115 DTAC questions

[Bob3700]

Mike,

I am not real focused on the 105B in the LR case as I see it's forte being heavier bullets (115grs). I will do some load work just to see where the upper accuracy node is.

My actual experience has been that a 107 SMK that is pointed has actually produced higher x counts for me. With Berger revising the BC of the 105 downward, I don't think that there is much if any BC advantage to the Berger. Tighter groups make the X ring bigger.

In the past, I know of several who are shooting 243 with the 105B and they are pushing them at 3200. That said, they have lost a bullet or two on the way to the target. That is why Berger came out with thick jacket bullets. I believe that when you are driving that heavy of a bullet that fast in a tight twist, you should consider some type of bullet coating to reduce friction and heat. Most who shoot a coated bullet have not had any disappear on the way to the target.

The other factor is bbl life. I haven't worn out a 243 bbl yet as I just started this project. My belief is that if you run a 243 anything hot all the time, it will contribute to a much shorter bbl life. I am hoping for 2000 competitive rounds out of the 243 Super LR. That will meet my expectations of equal performance to a 6.5x284 with longer bbl life.

Will post any results with 115 and 105 bullets.

Bob

 

[243Mendoza]

I can push the 115DTAC to 3100fps with H4831SC in the 6mm Mendoza which is a 243 with a 6br neck and shoulders

 

[rcw3]

I can push the 115DTAC to 3100fps with H4831SC in the 6mm Mendoza which is a 243 with a 6br neck and shoulders

Is this a bullet drag race? I don't get the point of this posting at all. I assume since there is no mention of accuracy and consistency, that it does not exist at that hot rod speed.

Robert Whitley

 

[JerryK]

I once asked a guy I worked with, how tight to torque a motor bolt I was installing. He said, "tighten it until it strips, then back it off a touch". I think that's where this thread went. My original intent was to see if the DTACs could be driven fast enough to be a good choice for 1000yd competition, if they would be an advantage over the 105/107 bullets. It seems maybe not. Does anyone have a good accuracy node for the 115's?

 

[Steve Blair]

As in my earlier post, velocities around 3180 are giving me very good accuracy and velocity spread with 7828 SSC. Below that, the best I have found is 2950-2970.

 

[Bob3700]

Jerry,

My experience with both the 105 Berger and 115 DTAC is that they are both good 1K bullets.

Here is what I ran into and what steered me in the direction of the 115 DTAC.

You can run the 115DTAC bullet easily to 3000 fps with very good accuracy in any 243 style case. An accurate load and seating dept are easy to find.

The 105 Berger is a VLD type and much more tuning is involved to get an really accurate load. The bullet is run faster than the DTAC so bbl wear may increase a bit with the 105. Speeds between 3100 - 3200 are usually what people are talking about with the Berger and a 243. They also talk about short bbl life when you are in that lofty FPS region.

I tried three or four different loads with the Berger and never achieved the level of accuracy that I received with the DTAC on the first load that I tried.

My goal is always to find a good accurate load without wearing an expensive and accurate bbl out on a bullet that is hard to tune.

No doubt that many matches are won with the 105B, It is a good bullet if you have the time and bbl to experiment with to find it's sweet spot.

Bob

 

[HPMike800]

Maybe it's cuz their pushing them so hard. I shoot alot of 105B's in a 6BR and a 1/2 min 600yd load is no brainer.

 

[rcw3]

In so far as accuracy, I find that the accuracy/velocity node for benchrest shooting is typically different than it is for F-Class and Prone shooting mainly because the F-Class and prone shooters need to go 22+ shots straight with no break or cleaning and most benchrest shooters do a few fouling and sighters then a 5 or maybe 10 shot record group and that's it.

In my load testing I have shot many fast or hot loads and they will shoot great for 10 - 14 rounds but then the group falls apart if you keep shooting. This is not a good load for F-Class or highpower prone, because you need to make it the whole way and stay tight. What I typically find is I need to drop the load back a grain or more of powder for the load to stay tight the whole way.

So it's hard to gauge things when guys jump on these forums and say they have an accurate load at 3100 fps, the question is what does that mean? Accurate for how long and how many shots in a row, and is what they posted even relevant to the type of shooting you want to do?

Since I do almost all highpower prone type shooting, all my load work ups go through 22 shot strings and I cannot tell you how many loads look great to start, but fail for consistent accuracy at the back end of the 22+ shot string.

Robert Whitley

 

[Steve Blair]

Well, Robert, I usually shoot 50 rounds while practicing and developing loads and have seen no significant group degradation with my 6mm 115 DTAC load. I am using hBN coated bullets and a 30" Bartlein 7.5" twist barrel. That is not to say that is everyone's experience but it is mine. The load is well below top pressure for the 6mm Rem and exhibits no indications. ES is in the low to mid teens.

I have always found the 6mm Remington an easy cartridge to develop. Barrel life is not great but accuracy has never been the issue.

 

[Bob3700]

Mike,

I have shot the 105B and 107 SMKs in my BRX and you are correct that shooting them in the 3000-3050fps range gets you some small groups. I use the 107SMK exclusively at 600yds and now at 1K with the BRX. I just get tighter groups with my 107s. I can't see any difference on target between the 105B and the 107 SMK once the SMK is pointed. The SMK is so easy to get to shoot, that while I have and shoot the 105B, it is not my first bullet of choice when I go to a match.

The bigger cases are not as easy to tune with the 105B. My 6mm SLR will shoot bugholes with the 107SMK at 3000-3050 fps but takes 10 gr more powder than the BRX to do it. So I am not looking to shoot the SLR so much at 600 yds prone.

I think a BR based case is almost unbeatable in the long run at 600 yds. Plus, the bbl will last a heck of a lot longer than any of the larger cartridges, so it is a no brainer.

Bob

 

[Dgd6mm]

My 25 shot string at 200 yards was shot one after the other without breaks. Group size under 1 inch. During testing at 600 yards I shot 3 - 20 shot strings in 20 minutes with only flagging ribbon for reading the wind and the outcome was high 190's. This was with a stationary target. I have shot 5 shot groups at 100 yards in the 0's to the low 3's, and at 1000 yards under 4.5 inch 10 shot groups. I will not bore you with anymore details other then this was shot with a 6CM 115 DTAC at 3153 27 inch Krieger on a Savage Action. No Robert, this is not a drag race.

 

[HPMike800]

I guess the question is, Is 2980+/- the limit for consistant accuracy with the heavyest target bullets?

You see it all the time - 115's in the 243/6rem, 140's in the 6.5X284, 180's in the 284 Shehane / WSM. Some of these cartridges can push the velocity higher, but, most shooters run them at 2950 or so.

If you go with 107's, 130's, 168's in the same cartridges is the same consistant limit still 2980 +/_?

 

[TonyR]

Mike,
My 284 Shehane gives great vertical at a little under 3100 fps with the 162 A-Max; but I absolutely agree with you about the 180 VLDs. Nice vertical nodes every 100fps or so from 2600 on up then it opens up at 3000fps even though I can get there without any great difficulties. Any theories about why this happens??

 

[RDavies]

Tony, I was thinking the reason 284s shoot better at the lower velocities (mine prefers 2800 over 2900+ anyday) is that the extra recoil with hotter loads makes gun handling more critical. To get to the big velocities you are speaking of would take major pressure, I wonder if the long 180gn bullets deform under very high pressures when you try to drive them towards or over 3100 fps?

 

[TonyR]

cr500.
I think that it is recoil related. Some of the 1000 yard BR guys shoot tiny groups with giant 30 cal cartridges with heavy, high BC bullets, but they do that with 100 pound guns with wide fore-ends and sometimes muzzle breaks. I shoot a 22 pound F-Class with a 3 inch wide fore-end whether it is a 6BR or 284 Shehane so the movement of my gun during recoil has to be different than those big BR guns. The question is what to do about it?