DTACS coming apart

[Ryan Eastman]

I was wondering if anyone else has had any experience with DTACS 115's coming apart. They have been very good bullets except for in the last two matches I have had two bullets experience sudden high intensity trajectory failure mid flight to the target. I'm not for certain if it may be the particular lot of bullets I have, or if this is more widespread and would like to know if any others are experiencing this.

Running around 2950 with a 1 in 7 twist barrel. 2 out of 300 have come apart mid-flight, but other than that they have been great.

Thanks

 

[Hoier]

I watched Henry Childs blow up probably 15 at our 2 day money match. It was weird I would see the grey puff at 50-100 yds but he still had a few holes in the paper at a grand.

 

[flatlander]

I think running any twist faster than 1:7.8 in a 6mm is asking for trouble like this. The only 6mm bullets I've ever had come apart short of the target were fired out of a .236" bore 1:7.5tw 6x47 Lapua - but they weren't DTACs. None of my 1:8 or 1:7.8tw 6mm bbls have ever had a bullet failure, even when running DTAC or Berger 115s to well over 3100fps.

 

[wc872]

I have never had a problem with 115 DTACS. I normally run them 2775 - 2840 fps in a 7.5 twist 6xc. Never a problem in 6 years of using them. The fastest that I have pushed them from a 6-284 is over 3425 fps without a problem. The 6-284 is a 7.5 twist Rock Creek barrel.
Semper Fi

 

[spclark]

0.66% failure's not really acceptable when it comes to losing points, is it?

How many rounds thru your 1:7 barrel?

Do you have access to a bore scope?

When I was shooting them in 6XC it was at ~ 2850 fps in a 1:7.5 PacNor 26". Never lost a single one & fact it shot really well at 600 yards. I later tried them in a 30" 1:7.8 @ 3100 fps & still didn't lose any but proved to myself that Berger's 105VLD @ 3,100 fps was a better choice, consistency-wise.

Personally I think 1:7 might be a bit too spinny for 'em at anything approaching 2900.

 

[teele1]

Yes, I've also has issues with 115 DTACs blowing up. I have attributed my issues to a less than clean barrel. After a match where 4 blew up, I scrubbed my barrel squeaky clean and haven't had issues again. Just MY experience. Your mileage may vary. 6CM Krieger 1-7.5 about 3050+ fps

 

[Ryan Eastman]

Yes, I've also has issues with 115 DTACs blowing up. I have attributed my issues to a less than clean barrel. After a match where 4 blew up, I scrubbed my barrel squeaky clean and haven't had issues again. Just MY experience. Your mileage may vary. 6CM Krieger 1-7.5 about 3050+ fps

That was a thought also, since both failures happened around shot # 45. Cleaning is not really an option for me though since this is an f-class match.

 

[teele1]

Mine was during a F/Class match also. Once I had my barrel really cleaned I could shoot an entire match without a blowup.

 

[jfseaman]

That would be leaving the barrel at over 300,000rpm.

If I understand correctly optimum is more like between 200,000 and 250,000 but YMMV.

It is my belief that at that RPM a little galling or imbalance from a dirty barrel could push the jacket over the edge and cause a 'blow up'.

I don't know if Sierra is still the source manufacturer for the DTAC but http://www.6mmbr.com/DTAC115hbc.html

 

[Dgd6mm]

I have the same barrel chambered the same as teele1. I had 1 Dtac blow up the sameday. Cleaned it good ever since and have not blown another one since. I have 3900+ rounds down that barrel, 2000 DTAC's on order, and about 1500 in my possession. I run mine at 3150 FPS.

 

[DukeDuke]

I have the same barrel chambered the same as teele1. I had 1 Dtac blow up the sameday. Cleaned it good ever since and have not blown another one since. I have 3900+ rounds down that barrel, 2000 DTAC's on order, and about 1500 in my possession. I run mine at 3150 FPS.

Amazing! Still shooting good?

 

[Elwood]

I have had the Dtac up to 3300 fps in both a 1-7.5 and a 1-7.8 twist barrel and have never lost a bullet.

 

[jfseaman]

So to recap:

DATA:
Bullet RPM over 300,000
Cleaned barrel and did not repeat blow up.
Multiple rifles and shooters experienced the same thing.

If it were me, my SOP update would be to 'clean' the barrel 'more'. Seems like y`all have come to that conclusion.

Since I've read of other bullets doing the same thing, particularly V-Maxes being pushed past 300,000 RPM it seams like barrel hygiene is a factor to watch in blowups.

 

[Dgd6mm]

I have the same barrel chambered the same as teele1. I had 1 Dtac blow up the sameday. Cleaned it good ever since and have not blown another one since. I have 3900+ rounds down that barrel, 2000 DTAC's on order, and about 1500 in my possession. I run mine at 3150 FPS.

Amazing! Still shooting good?

Yes, still shoots good. July 23rd I cleaned it down to bare metal and polished the throat. I do this every 200-300 rounds. My notes show 271 to be exact. I use a copper cleaner when I feel a need to. July 31st I took it to 600 yards and shot 37 rounds that a.m. I was working on my .308 FTR rifle and took the 6MM Competition Match to see what kind of group it still holds. In prone it sighted right away, last 10 shot group measured under 3 inch.

 

[Ryan Eastman]

Just a little update. Made it out to shoot some more yesterday, and intentionally left the barrel uncleaned from the last match. Shot another 30 rounds through it with the DTACS, and had about 10 more failures. The last 5 in a row failed. Then changed to Berger 115's and did not experience any failures for 25 shots. Verified the speed again was still at 2970.

 

[Dgd6mm]

Whynox, not that I'm telling you what to do, but if it was me, I'd be calling SSS and tell them about your findings. I'm sure they would be curious of the lot #. They may also replace the ones you have left. Do you know the diameter of your bore? I'm a believer that the DTAC is better suited for a .237 bore.

 

[tonysnoo]

I searched and found this old thread.... I thought I would share to see if this is still happening.

I was out at a practice day. Thought I would work up/verify some loads using my new reworked Lapua Palma brass in my 28" 7.5 Krieger barreled 6SLR.

I had 30 rounds down range with 108 burgers and various powder charges. I had loaded some lower end charges with some older DTACs. Out of nine shots fired only 4 imprinted a 100yd target. My spotters said all had vapor trails.... some pooped into dust clouds before the target... some just diverted or splattered 15" off target to the side.

I ran 10 more much hotter Berger 108 loads (.6-.8 grain more) with great results. I'm wondering if there were a bad batch of Dtacs out there a few years ago?

Thanks.

 

[Hoser]

I have been shooting DTACs at 3000 - 3200 fps out of 8 twist barrels for years in a 6CM. Kreiger, Brux and Bartlien.

One of the barrels was cleaned every 500-700 rounds, if I felt like it.

 

[tonysnoo]

Yeah... for sure. Ive run many DTACs in the past too, but mostly around 2950 on my older barrel. I still run 7.5 twist but have been working with hybrids and now most recently 108s for a couple of years. Thought it might be fun to test the dtacs against the 108s. This barrel is faster than my old one for who knows why. I have another box of them beside these, but now it makes me wonder if it was only an isolated lot number that was problematic.

I have blown up lots of AMAXs but never anything else. I definitely don't clean as often as some... maybe every 200 rounds. I guess ill clean it and try some more now that I'm curious.

 

[rcol317]

Very interesting thread, I'm expecting my new 6 XC tomorrow with a new 7 twist. Was hoping to run 115 DTAC's and 115 VLD's sounds like I may not be able push them that much with that much spin. Was hoping to send them @ 2900-3000 for a good 300-600 yard rifle. It will be interesting to see what happens. I've got 1,500 bullets waiting to be used?