6mm Rem with DTAC 117 BN Bullets

[mysticplayer]

Eric, Just spent some time reading your report. Very interesting indeed.

Would there be a difference in heat if a shorter barrel with a larger case was used to reach the same muzzle velocity as a small case/long barrel?

By reducing bore friction,shorter barrel) but increasing 'thrust',larger case, more powder burnt but at lower pressures), can we reduce the core temps so bullets don't blow up but we get the speeds we want?

Jerry

 

[EricStecker]

Jerry,

We had not pursued making a lighter bullet by using something other than lead to see if this affected the bullet failure. Our highest priority is consistency and precision. Copper and lead are great for producing both. Other materials do not come close to the level of precision acheived with copper and lead.

Frankly, we talked about using different materials but quickly dismissed this option,to solve the bullet failure question) based on what I said above. Using less dense materials would be the only way we could go lighter while maintaining volume.

It might be possible that this would work but we have no data or testing proving anything either way.

Regarding larger case and shorter barrels, we have not done any testing so my opinion is pure speculation. The way I see it you are dealing with the same compromise but with different characteristics. Shorter barrels will not heat the bullet up as much as a longer barrel under the same conditions. This is true however, larger cases produce more rapid throat erosion and higher velocity and pressure,assuming the load consists of more powder) than smaller cases. This may bring you back to the same friction causing conditions you had with a smaller cartridge and longer barrel.

This is what makes reloading so interesting. When you build a bullet delivery system and then select the bullet it is like putting a fantasy football team together. Each component has its strengths and its weaknesses. If there were a "best way" to go then we all would be shooting the same rifles. Even the guys at the top do not agree on which combination is the best.

Short range BR is mostly made up of 6PPC shooters. However, what many people don't know is that due to the nature of the extreme precision needed for short range BR their is another level of compromise occuring below the "everyone shoots 6PPC" surface such as all the various options with case preparation, bullet configuration, neck tension, chamber dimensions, ammo components and loads that change from target to target at the range during a match.

Even though their rifles are chambered for the same cartridge, short range BR shooters using 6PPC also making compromises which occur at a much tighter and finer adjustment level. My point is that there is no "do it this way because it is the best". Those who say otherwise are only relaying what worked for them and it will not be true in all rifles.

Regards,
Eric

 

[mysticplayer]

Eric, thanks for the feedback. Maybe there will be some new break through shortly.

If so, please let us know.


Jerry

 

[ConnorExum]

Jim, I suppose this is not hard evidence, but I have shot 500 DTAC 117 Boron Nitride bullets through my 6xc Kreiger one in seven and a half twist 30 inch barrel and no blown up bullets and very good accuracy. That finished my first box of bullets and a few days ago I started on my second box of 500. I shot 15 bullets out of this second box through a 6CM chambered Kreiger barrel again one in seven and a half twist but this time a 32 inch barrel. Those 15 rounds again were extremely accurate at 600 yds. MY muzzle velocities are in the 2990 range. So far I have not noticed any spotty coating on the bullets, but I will pay more attention now.
The fact that some folks had bullets with bent and missing tips and others had bullets blow up seems to indicate to me that certain lots of these bullets do have a problem. I just ordered another 500 of the lot that has been working well in my rifles. I am hoping my luck holds. I would expect Sierra and Mr.Tubb are investigating why some of these bullets are being returned.

I couldn't do the test if I wanted too, I don't own a rifle chambered in any 6mm cartridge. Otherwise I would do the test and show the results for all.



Bob [/QUOTE]