115 DTAC vs 107 SMK

[Bob3700]

Gents,

I wanted to avail myself of experience that is already out there.

This discussion is about 1 K shooting.

Seems that one school of thought on the 115 DTAC bullet is that it needs a long bbl,30") to take advantage of the higher BC. The reason is that you need the extra bbl length to get the 115 up to 2950-3000 fps. as that is where it's extra BC is an advantage.

Through a shorter bbl, the 115 DTAC velocity is enough lower that the 107 SMK,with its higher velocity) is an even match on the target.

XC bbls are typically 25-27" in length and most will say that they cannot get anywhere near 2900 fps with the shorter tube using the 115 DTAC. So, the 107 SMK is the bullet of choice for shorter bbls due the higher velocity,2950-3000 fps).

Anyone want to comment either way?

Bob

 

[Spotcheck_Billy]

You didn't specifically mention what cartridge you're using, but I take it from your post that it's the 6XC. D. Tubb reports velocities up to 3020fps MV out of a 27" barrel, but he's using moly coated DTAC's. I would think that 2950 would be feasable with naked DTAC's and that should allow them to fly flatter and buck the wind better than the SMK's at 1000yds. due to the DTAC'S superior BC. I'm not shooting a 6XC, so the above is purely speculation, but hold on for one second .......

I am, however, using the 115 DTAC's naked in a .243 Win. with a 28" 5-groove 1/7 twist Pac-Nor barrel with reasonable loads of RE25,I'm looking for improved barrel life) and getting 3049 MV and it takes considerably fewer clicks on the elevation and windage knobs at 1000yds. than any combination that I've tried with the 107SMK bullet.

In my experience the 107 can't be driven fast enough to overcome the DTAC's BC advantage.

Alan

 

[Bob3700]

Alan,

I am sorry, yes I am speaking about the 6XC. Agree that the 115 DTAC at 3000 fps has an advantage over the 107 SMK.

The problem is that with the 6XC, no one that I know, can achieve 3000 fps with a 115 DTAC with a bbl in the 25-27 " range. They all run into pressure signs way before that. They are all using Moly'ed bullets by the way.

If you have to start the 115 DTAC out at lower velocity than the 107 SMK, then it seems that the BC advantage is netgated. Then you are better off using the 107 SMK at 2950-3000 fps at 600 and 1K yds.

BB

 

[lee_eastridge]

I use the 115 and get 2900 fps without pressure signs.


h 4350 38g 2.750 win brass Russian primers 115 d tac molly.

I also bought some ammo from SSS and it was loaded with 39g +
and the brass looked just fine after shooting in 100 deg weather
i did not chrony the loads but i assume they were in the 3000 to 3050 range.

The brass has alot to do with getting the velocity.

oh yea . Schneider 28" . the brl that came with the gun.

 

[bcott]

My 6XC loading data for the 115DTAC,moly): With 38.0/H4350 & WLR primers I get 2879fps w/16fpsES. My AOL is 2.720" This is fired out of a T2K rifle and the 28" barrel. I am using Norma 22/250brass. I also purchased several boxes of Tubb 6XC ammo,115DTAC moly bullet) and broke some down. They were 39.3gr/H4350, Russian primers & a 2.730"OAL. With the extra l.3gr of H4350 I would assume they are getting close to 3000fps. I did NOT chrono the Tubb load though. Surprisingly enough, through my sources the 115DTAC bullets,500 perbox) were a couple of bucks less per box. I only went to 39.0gr/H4350 in my testing. 38.0/H4350 gave slightly better accuracy so I went with that. We only have an 800yd. range here & I only fire F class locally,600 700 800). I guess you could say I am not a serious F shooter. But I have fun anyway.

I will stay with the 115DTAC bullet as I DO support the D. Tubb project overall. He took a very large risk with some very real money to get all this going. Besides being loyal does not cost anything extra in this case.... Carl L.

 

[theduck]

I have loaded my 6mmxc with Moly 115 DTAC in the NEW Norma brass with a 27.5" @ Tubb's specification contour polygon barrel.
I use H4350 and fed 210gm.
I have never been able to achieve more than 2800 fps with using Nosler 22-250 custom brass without Very high pressures and at this load i get 2-3 firings out of the case, so i quit shooting the 115 and shot the 105-107 since.
But with the new Norma brass i loaded 39g H4350 at achieved 2870fps with ejector signs, when i reloaded the brass the primer pockets were still tight but not like new.
I think this is very close to my MAX load and the brass at this pressure should last maybe 5-6 firings.
Just to let you know on all of my Norma brass the primer pockets were very shallow..to the point which the primer stuck out of the bottom of the case but was fixed when i recut the depth.
Also i tried the new Lapua 6.5x47 brass fire formed to 6xc which took the pressure well but accuracy was bad, i think it was possibly the small neck length or the 38-39g of H4350 with the small primer, and yes i did suffer from hang fires miss fires and very inconsistent velocity's.
Hope this info helps

 

[Forum Boss]

I just got off the phone with Rick Beginski who has built three 6mm-6.5x47 Lapua bolt-action rifles, one for himself and two for customers. He reports no problems with ignition, hangfires etc. Rick is shooting 108gr BIBs with H4831sc and he says the rifle is extremely accurate and the ES/SD is low and consistent.

Rick told me Roger Amos has a 6mm-6.5x47 and was having some ignition problems, but these were corrected by replacing the firing pin spring. The original firing pin spring in Amos' action was shorter than spec for some reason. Apparently, before swaping in a new spring, Roger was able to solve the hang-fire problem by reaming the flashholes to .080. However, with the new spring, that has not been a problem.

 

[Wild_Bill]

I just got off the phone with Rick Beginski who has built three 6mm-6.5x47 Lapua bolt-action rifles, one for himself and two for customers. He reports no problems with ignition, hangfires etc. Rick is shooting 108gr BIBs with H4831sc and he says the rifle is extremely accurate and the ES/SD is low and consistent.

Rick told me Roger Amos has a 6mm-6.5x47 and was having some ignition problems, but these were corrected by replacing the firing pin spring. The original firing pin spring in Amos' action was shorter than spec for some reason. Apparently, before swaping in a new spring, Roger was able to solve the hang-fire problem by reaming the flashholes to .080. However, with the new spring, that has not been a problem.

That is interesting i have been involved in building 3 6X47 LApua's here in Australia we are using the 107gr Sierra and have got excelent results with H4831SC aswell a full case of it and a Rem 7 1/2 primer was the best. we tried CCI450's and PMC magnum primers aswell with no troubles at all with ignition also with H1000. the problem with ignition comes when using a mild primer and the larger cases but use the correct primer and these things realy shoot. all groups at 200m have been under 1 1/4" but the best combination had groups clover leaf under 1/2" at 200 metre's we wil be trying the 115gr Berger next week if they arrive on time it should be an awsome setup. One of the rifles is for the gunsmith i help it is a meliniup in a flexibed bedding system the latest mastin F Class low riding stock and a custom barrel tuner we have designed we will do an article on it and post it as soon as the stock is finished this week and the rifle is run in and tested.

Cheers Bill
Australia