So you want a 6mm/AR.....

venatic

venatic

Active member
Last fall I saw where Mike Milli(DTech)was taking the 6.8SPC and simply necking to 6mm and it was called the 6mm DTI. I spoke with him about it and asked what it would do compared to my 6X45mm. Well after I listened to his reasoning that it was a niche cartridge between the 6X45mm and the 243 WSSM I told him that I was in for one knowing full well it might take a while as behind as he was. Well guess what showed up last Tuesday.... A 22inch Shilen Select 1/12 twist 6mmDTI along with some dies and SSA 6.8SPC brass. It did not take long for me to make some ammo(very simple) and get to the range shoot a few rounds, check the speeds on couple of loads and realize Mike has a winner here.I probably need to add that you do fire-form the brass which changes to shoulder angle but as I have found in the TAC 20 it shoots the same speed-wise and accuracy-wise so you can go kill stuff while fire-forming.
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Here is the first of what I hope to be many victims shot Thursday night under a full moon.... the load was 80gr Sierra Blitz loaded with VV530 traveling 3265fps.

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I did not take pictures of the first few groups I shot but they all were between 1/2 to 3/4 inches at 100/200yds both. I went this morning thinking I would catch the wind calm and get a picture of a few groups... well there was a thunder storm off to the NE and the winds were gusting right into my face as I was trying to shoot so my groups were all vertically strung ( that's my excuse and you have my permission to use that if you ever need to)
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anyhow... here is a picture of the worst groups I have gotten so far!

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The 6 x 45 you have is not compensated, and neither is the new 6mm DTI. How is it without the compensator? Are you able to retain sight-picture?

My DTI has the compensator, so I was just curious what you are seeing without the comp.
 
Awesome! thanks for sharing. That is good news! I recently change a 243 WSSM I had on order to the 6mmDTI after a long conservation with Mike. I already have his 25 WSSM and 20 Tactical the 6mmDTI would be a good fit between the two.

Was the neck down of the 6.8 brass easy and do you see a need to anneal?

Thanks

Mike
 
Originally Posted By: DtechThe 6 x 45 you have is not compensated, and neither is the new 6mm DTI. How is it without the compensator? Are you able to retain sight-picture?

My DTI has the compensator, so I was just curious what you are seeing without the comp.

Recoil was mild actually less than I was anticipating.Yesterday I shot my .223 back to back with the 6mm DTI and there is not an appreciable difference.I shot that hog at 10:30pm by moonlight and watched him drop. Oh and with the 22inch barrel with the load I used the muzzle flash was minimal FWIW.

MikeinLouisiana

The brass was easy... really not much different than making 6X45mm except when you fire-form you can see a change in the shoulder angle. No I did not anneal and am speculating that it does not really need it although once you have fired it a few times you might try to extend the life by annealing.I only sized 30 pieces so I will probably just keep using that brass over and over to see how long it lasts before using the remainder.
 
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I don't think you will find anything as easy as a 6 x 45 as far as brass-prep. The 6mm DTI is not far behind though! It is very simple. You simply run the 6.8 brass through the DTI full-length sizing die. That brings the neck down to the correct size, but the shoulder is still at the original angle.

Once you fire the brass for the first time, the shoulder moves forward to the 30^ and from that point on, it's load and shoot.

Venatic had mentioned that the "fire-forming" process is accurate enough "to kill stuff with". Well, when you look at the size of animal he took with it, there should be no doubt that fire-forming should be accurate enough. I have taken white-tail all the way down to prairie dogs with the 6mm DTI and have found the non fire-formed cases to be accurate enough for even long-range prairie dogs. I have shot some groups side by side with non fire-formed brass along side of fire-formed brass. You can see the difference on paper, but it is VERY minimal.
 
Cool. What is the shoulder angle on the DTI? The reamer I had made has a 40 degree shoulder with a .238" neck length and very minimal body taper. VV-540 has given me some impressive velocities with 85 and 88 grain bullets (yes, in a bolt gun with a long barrel).
John
 
John, I went with 30* on the DTI. It's not much of a change, but I built a couple (one in 10 twist and one in 12 twist) with the original shoulder angle, and after pushing the shoulder forward to 30* we got much better results.

I've been using TAC, H-4895, AA-2015, AA-2520 and RL 10-X in bullets from 55-85 grains. The AA-2520 does quite well with the 85 grain bullets, and the H-4895 does very well with the 70 grain bullets. I'm going to have to get my hands on some of the VV powders and give them a try. 3265 FPS out of a 22" barrel with no high-pressure signs is pretty encouraging!
 
Now you guys that own a 6mm DTI, I know you guys have 1 in 12" twist or 1 in 10", I was wondering though if there was a barrel with a 1 in 8" twist is it possible to load the 105 grain class of bullets to mag length without having to single load the cartridges?
 
For the long, heavy bullets, the 6 WOA is the way to go. I have been building it longer than the DTI, but it is build primarily for the longer bullets. The DTI shoulder is pushed forward for more powder capacity, but WOA is pushed back for more room for long bullets.

Here is a photo of the DTI on the left, and the WOA on the right.
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The problem we have had with our design is that it does not show pressure signs. I had already decided that if I were going to revisit this project, the shoulder angle and the body taper was going to be a bit more conservative. With cases that showed no signs of pressure, the primer pockets were loose after two firings. I guess I could have had the barrel cut for a transducer, but this was suppose to be a fun project. Nice job with the DTI.
John
 
Thanks for the pictures Mike I was curious as to the exact differences between the DTI and the WOA. I was mainly interested in bullets from 65gr to 85gr range so the DTI fits my needs.
I got some 80gr Sierra Blitz to try based on a post pcammo(John) made about how they shot in his 6X45mm. After I shoot a few coyotes with them I will know more but so far so good.
 
I feel the 6mmAR Turbo would do the long bullets better since its parent case the 6.5 Grendel was designed to seat the longer 6.5mm High BC bullets yet still fit in the standard length AR mags. I was just seeing if anyone has done so out of the 6mm DTI. I know the 6mmAR Turbo will do 2900 fps with 105 grain bullets with the same C.O.L. as a 223 Rem.
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I've never loaded for either the 6mm AR or the Turbo. I have on the other hand loaded for the 6 WOA, 6mm DTI and the .243 WSSM.

The case capacity on the WSSM (to overflow) is 53.9 grains. The capacity of the 6mm AR is 36 grains, measured the same way. I don't have a number for the Turbo, but it is probably around 39 grains. Given all that, the WSSM with a working pressure of over 64,000 is just able to push a 105 grain bullet at 2900 FPS, with my loading.

With a smaller bolt, and less case capacity, I don't see how they are going to get 2900 FPS out of the Turbo without ruining brass.

I think if the same person loaded both cartridges to what they felt was a safe pressure limit, there would be quite a difference in velocity between the WSSM and the Turbo.

All this is slightly irrelevant as I have no intentions of paying a royalty to build an upper, so the Grendel and Turbo are not going to be part of my line-up.
 
Originally Posted By: venaticI got some 80gr Sierra Blitz to try based on a post pcammo(John) made about how they shot in his 6X45mm. After I shoot a few coyotes with them I will know more but so far so good.

I've got a bunch of those 80's sitting on the shelf. I was hoping they would be a good yote bullet in the 6x45 upper I've got ordered.
Keep us informed!
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