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6mm Rem with DTAC 117 BN Bullets

rcw3

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Today I put on my new 6mm Rem 30" Schneider 1:7.5" twist polygon barrel on a rifle to try out the DTAC 117's,boron nitride coated). Did not do any accuracy work, just chrono testing as follows:

All loads with new Winchester 6mm Rem brass neck turned to .269" loaded. Chamber has a .272" neck. All loads with Russian primers and all bullets loaded .015" in the lands. The chamber was throated out long for the 117's so the junction of the boat tail and bearing surface of the bullet was just ahead of the neck and shoulder of the case.

46 gr N165, 2969 MV, ES 26, SD 12
47 gr N165, 3039 MV, ES 16, SD 6
48 gr N165, 3096 MV, ES 23, SD 8

48.5 gr H1000, 2961 MV, ES 18, SD 7

There was no excess pressure with any of the loads.

I will be trying 49.5 and 50 gr of H1000 in the next day or so as well as 48.5 of N165. I really cannot see much reason to push things over 3100 fps for match shooting so my accuracy load workups will probably focus on the area betweeen 3000 and 3100 fps.

Robert Whitley
 
About 3.125" OAL - pretty long with those 117's. Lately I have been doing some accuracy testing with them, but that is not going well at all. I will probably put them aside for now and go with something else.

Robert Whitley
 
How is the testing going with the 6 mm Remington Robert? Have you tried any other bullets aside from the 117's?

Thanks,

Chris
 
Chris

Initially there was a problem with the barrel for the 6mm Rem and it shot poorly no matter what I shot out of it. I just had another 1.5" cut off the muzzle to get rid of the problem,i.e. very rough tooling marks in the bore and not lapped or badly lapped at the muzzle end and picked up huge amounts of copper). Yesterday I did some accuracy testing with the Sierra 107's and DTAC 115's to see if the barrel issue was resolved, and it appears to be resolved, but now I am down to a 28.5" barrel instead of the 30" barrel it was to finish at.

I am also currently not confident with the DTAC 117's,boron nitride coated) as I went to a 1000 yard match a little over a week ago,with a different 6mm cartridge) and I had two of them vanish into thin air for no apparent reason,only going 2950-2980 fps). At this point I will try other bullets.

Robert Whitley
 
Are there anyone else having problems with the new 117DTACs BN? I am having bullets desintegrate in mid air, Sometimes even at a 100yds no hole on paper. Does anyone figure it out what is causing this?
Thanks
Ron
 
Ron, I have fired about 250 of SSS 117grBN bullets through my 30" 1 turn in 7.5" twist Krieger barrel,6xc chamber) and have had not had any bullet blow ups.
My lot of bullets have no bent or missing tips. The lot I have is lot 7055XX. I just called to order more and SSS is sold out of 117gr BN bullets until some time next month. And it seems that particular lot was in demand.

I am using H 4831SC powder and CCI Br2 primers.

Bob
 
Bob I bought 3000 of these 117 BN DTAC lot #7055xx. I've shot about 600rds out of a 243 Win with a 28" Schneider 7.5 twist at 2980fps. I've had a lot of them disapper in mid air, I've even had one going into the 100yd target completely sideways. I've inspected the tips and they look fine. I don't know what is causing this. I am not the only one having this problem. I've read about other people with the same problem. I am just going to send them back and switch back to the 115.
Ron
 
I think there has been some discussion about opposing land barrels. so 4 and 6 groove barrels may shred these bullets easier than 3 or 5 groove barrels.

If I had the time to tinker I would invest in a 30 inch 3 groove 6mm tube from Pac-nor and see how it goes.

I have heard 105 bergers also blowing up, 115 bergers, 117, 115' DTAC's.

Maybe you guys should stick with the 105 scenars.

RHINOUT!
 
Rhino

I never had a DTAC 115 blow up at any reasonable speed. I imagine someone has tried to run them 3250+ fps and lost one, but that's kind of an extreme velocity and I don't go there.

Robert Whitley
 
Ron it really is strange. My velocity is about the same as yours 2950 fps. I have the same twist rate but a Krieger barrel. I set my bullets to just touch the rifling, not jammed, although I tried jamming .020" but I still did not get bullet blow up. I just started to get sticky bolt lift and ejector marks on the case head.
In the past I did have problems with the old Berger moly 115's blowing up and I had one out of a few thousand DTAC moly 115's blow up.
My barrel has about 1000 rounds through it now. Too bad we couldn't have a competent gunsmith or barrel maker bore scope and measure the diameter of both our barrels for a comparison.
 
Couldn't the problem be with thickness of the jacket? If the jackets aren't meeting the specificed thickness given the forces of gryoscopic stablization I can see bullets blowing up at even reasonable speeds. Some one needs to do finite element analysis of bullet and see exactly when a bullet of this type will blow up given a specific velocity and jacket thickness before people start talking about barrel issues. That would be my first area interest, than I would look into rifle design and finally barrel specs. Because if this is happening to many shooters it is doubtful that everyone is having a bad barrel. it is more likely that a quality control issue exists with manufacturing of the bullet's jacket.
 
rcw3 said:
Chris

Initially there was a problem with the barrel for the 6mm Rem and it shot poorly no matter what I shot out of it. I just had another 1.5" cut off the muzzle to get rid of the problem,i.e. very rough tooling marks in the bore and not lapped or badly lapped at the muzzle end and picked up huge amounts of copper). Yesterday I did some accuracy testing with the Sierra 107's and DTAC 115's to see if the barrel issue was resolved, and it appears to be resolved, but now I am down to a 28.5" barrel instead of the 30" barrel it was to finish at.

I am also currently not confident with the DTAC 117's,boron nitride coated) as I went to a 1000 yard match a little over a week ago,with a different 6mm cartridge) and I had two of them vanish into thin air for no apparent reason,only going 2950-2980 fps). At this point I will try other bullets.

Robert Whitley
Robert the following is my recent experience with the 117DTACS b/n coated. two rifles both Surgeon single shot actions
Schneider 30 " 5P 7.5 twist hv 8
243 AI
pillar and skim bedded
Ammo : 117 Dtacs b/n
Lapua cases
RL 25 46.3 grs for rifle 1 and 47.2 grs. for rifle two
FED 210 GM
seated long ,bolt closing sets final seat depth

Velocity /es rifle one : 3044 avg /18
rifle two : 3007 avg / 11 es Oehler 35p with 8 foot bar

group sizes rifle one and two : 3tenths at 100 with many going in the mid twos, 5 shot groups ) .750 at 300 3 shot groups


Rifle one seems to have a tighter bore , note the velocity difference and powder weight difference between the two rifles . Also when first cleaning session occurred the same jag and patch for rifle two could not be pushed through rifle ones bore . Had to buff jag down and is still extremely tight . This condition persists at current round count .

Rifle one has 350 rounds through it and two has 210 rounds . Both rifles received same breakin treatment , i.e. shot one /clean for 5 round s , shoot two and clean for 5 sets, and shoot 10 then clean . The last step was not necessary as the bore was not copper fouling any more .


At the Camp Robinson 1000 yd f class and palma shoot in June rifle one was the only one of the two shooting . elevation comeup was determined by using Exbal and the first sighter was around .5 moa low and centered .Oily bbl on that shot so sighter two was fired without any changes and was slightly high and centered . Down .5 moa , fire third sighter for a x slightly left .Record firing began at this point and the shots were 10, 9, 10 , X, 8, 9, X , M . Calling for the target to be rescored we were told by the pit crew that the bullet did not " Crack " down range at the pits , they only heard the boom of the rifle from the firing line . Next round sent down range for a 10 , then two shots later two " nonarrivals " in a row . The remainder of the string same as the first part .

The second 20 round string was without mishap , score was 193 5x, we are complete novices at the long range game and wind reading skills amount to comments like " yup ! its blowing ", hence the avg score ) and the third string had two nonarrivals . The vertical component of all shots fired was approx .3 moa .


Lots of head scratching and research reading went on between the June match and the just completed July match at Camp Robinson . No changes were made to Rifle ones load as it is not near the pressure max and did not think lowering the velocity was any fix . Rifle one was tested up 48 grs of RL 25 with resultant velocity avg of 3212 fps . This was a primer pocket killer however so we went back down to the next node of 3100 and then to 3044 as it had the best es .

Rifle two was ready for the July match and it was shooting the 47.2 gr charge of RL 25 . Both rifles were shot for confirmation of velocities the day before the match , 10 rounds ) and left with a fouled bore .

rifle one had a " nonarrival " the middle of the first string , by this time the pit crew had a clue and was quick to report no " crack " at the target . There were two more that string so we cleaned the rifle between strings .

In the meantime rifle one fired a mediocre 20 round string , that wind thing again ) of 180 3x . The vertical component was practically nonexistent . This was repeated with its second string with a slight improvement , 187 5x . The final string of the day for rifle two the day had warmed quite a bit and the string was being fired rapidly, read barrel was smoking hot ) when the first " nonarrival " for rifle two occurred . After a pause to drop the bbl temp a bit the firing resumed and the string was completed without mishap . Rifle two had around 70 or so rounds down the bore and was extremely hot before it suffered a bullet loss .
 
Jimm

I spoke to Superior Shooting today on the 117's. They said they are working on the vanishing bullet issue with Sierra. They also indicated that it does not happen with all barrels, only with some, and that some shooters are having no issues with the bullets. If that's the case, it seems to be "hit or miss" whether you get a barrel that will shot them without issue. At this point, I will wait a while to buy any more 117's until they indicate they feel they have things nailed down and resolved. It's unfortunate because I like the bullet and will happily shoot it as long as it is a consistent performer without unexpected issue.

Robert Whitley
 
I have come to the conclusion that it is a combination of heat,
increased friction due to fouling, tight bores, and thin jackets
that is causing erratic bullet preformance
i'm playing around with some lapua scenars right now got some sierra 107s ordered i have been told these two bullets have
thicker jackets
I like the idea of the compressed air to cool the barrel seems practical, even during a match
 
rcw3 said:
Jimm

I spoke to Superior Shooting today on the 117's. They said they are working on the vanishing bullet issue with Sierra. They also indicated that it does not happen with all barrels, only with some, and that some shooters are having no issues with the bullets. If that's the case, it seems to be "hit or miss" whether you get a barrel that will shot them without issue. At this point, I will wait a while to buy any more 117's until they indicate they feel they have things nailed down and resolved. It's unfortunate because I like the bullet and will happily shoot it as long as it is a consistent performer without unexpected issue.

Robert Whitley


Robert , I have contacted them as well , before I posted here. David is away for a week by my understanding and I have not had any communication with him yet .

I also consider it unfortunate that there is this problem with them as I like the accuracy I get out of them and the .600 bc is a plus for sure .

At this point I have about 1400 of them on hand . 400 are the 750whatever XX lot and the remaining 1000 are lot 1620xx . I have not fired any of the new lot . Kinda waiting to see what might get figured out .

I look forward to this being resolved and continuing to shoot these bullets when they are " improved " .

Jim B
 
Those of you out there that have followed this thread , What do you think would solve this problem from the rifle end ?

I'm thinking that 2" off our 30 " bbls would completely eliminate the probl;em of " vanishing " bullets for rifle one and two .

Any thoughts ?

Jim B.
 
How much velocity loss do you think you'd suffer with the loss of the two inches of barrel?

I've been contemplating a 30" Palma taper 6mm Rem barrel for my match rifle. If I go that route, perhaps I should stick with the 115's.

Guy
 

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