Interested in Comments on 70 Grain 6mm Speer TNT

[MQ1]

Folks,

I have been using the 70 grain speer TNTs for fireforming my .243 AI because they were about as inexpensive a bullet as I could find.

I was surprised to find that the fireform loads easily put out half inch groups, and the velocity was in the neighborhood of 3600 fps.

Tonight, I read on the box that the TNT should not be used in excess of 3400 fps. ,

Now, of course, :idea: after horsing around with more expensive varmint bullets, I'm thinking that the TNT is probably my best choice for all around varminting...and I want to know what I can expect if I push this bullet a bit faster,which I believe that I easily can in this rifle).

BTW, my rifle has a 1-12' twist Hart barrel that is finished at 26'

What are your experiences with the 70 grain Speer TNT? What are your experiences with the reasonable upper limits in velocity, and what can I expect the terminal performance to be?

MQ1

 

[Dave223]

I've been shooting some 70 TNT's out of my 6BR. There is nothing wrong with them at all. I have used them on rabbits, hares and crows so far and they are a devastating projectile and accuracy is very good.

 

[WOLF2]

i used the 70 grain tnt in my .243 rem 700 vls sending them at 3600 and some did'nt reach the target. i now use the 58 grain v-max sending them at 3900 with no problems.

 

[soldierofchrist]

With your barrel twist you may be able to push them a little faster since most factory barrels are 1 in 10' while yours is 1 in 12'. I'm guessing the velocity that your pushing is about on the edge of what the bullet can take before it throws it jacket off from spinning to fast.

 

[MQ1]

soldier,

That is what I was thinking...that I may be able to get away with a bit more velocity because of the twist...

I'm hoping that some persnickity, data loving rifle nut with a chronograph will pipe up and share what they know in regards to how fast this bullet can be pushed before it disintegrates in flight

Not that I can't find that out for myself...of course I'll have to do that anyway...but it is always helpful to have an understanding from others who have treat the path before me...

MQ1

 

[golfer2b2000]

I have also used the 70 grain TNT..I do basically because it is less expensive than others. I am shooting it out of a 6mmBR, and my accuracy is very good. Now I am not a benchrest shooter, but not a bad shot either. I can group for the most part 1/2 inch groups, and my rifle is a 1-12" twist. This is about the heaviest bullet I can shoot though. I usually dont get to shoot chucks more then 300 yards away, but my success rate is quite good also. And they do a great job as far as terminal damage goes also.

 

[Ackman]

That's a one size fits all warning. With a good barrel they handle a lot more speed than that. I've been shooting them in my 243AI's for years. One gun has 13" twist, the other is 9-1/2". With a 70TNT the accuracy load in either gun is high 3700's to 3850. Never had one blow up until it hit something.

Same thing with .22 cal.....the 50TNT is very accurate at 3825 through a .223AI. But just to find out......in a 22-250AI at around 4200 not one made it to the target. The limit is somewhere in that 400fps window.

****With a 70TNT and 760 powder, fireforming loads were in the high 3700's.

 

[MQ1]

Ackman,

Thanks for your post...your experience is exactly what Iwas hoping to hear.

I'm hoping that I can find an accuacy node around 3800, and knowing that I have a pretty slick Hart barrel, I think I'm going to have to load up a couple test rounds and sort out the details...

I know that you are fond of 760..have you used much Varget or H4350in your 243AI's?

MQ1

 

[Ackman]

MQ1,
Never tried 4350 in that case. Varget works well for some people but it doesn't meter well and has never shot very well for me.......760 has always been real accurate in .243 and .243AI. Fireforming load was more than 48gr/760 with a 70. Start about 46.5 and go up. With formed brass it's about the same.

My 243AI reamer is minimal.....0 freebore, .273"nk, length about .010" longer than brass, and web dia. is just small enough that Lapua brass won't fit.

 

[Steve Blair]

I used the Speers in 6mm Remington and around 20% never reached the target. The 6mm has about the same case capacity as the .243 AI but has a 9" twist. You might get away with it in your barrel. The best way to know is to try.

The Hornady 58g V-Max Moly is very accurate in one of my 6mms, giving 4055 fps from a 25.5" barrel with 48 Varget and single-digit ES. I use H4350 for all bullet weights 70g and above.

 

[MQ1]

Ackman,

I'm probably gonna make you laugh, but my 70 TNT experiment got me to just under 3700 fps with Varget.

Low and behold, I found 10 test rounds I built in the past with a generous helping of H380 and some 55 grain Ballistic tips. Holy Smokes! 4200+ fps, somewhat flat primers, and 1/4 inch groups. I recognize that H380 is just a number away from your favorite 760...I think that I'm going to have to drop a couple 70 tnts on top of some H380 and see if I can replicate the accuracy and lower the erosion rate I have a couple pounds of H380 and was wondering what I was going to do with it...I think I now know...

MQ1

 

[25AI260]

i'm just getting started with a 6mBr.. don't have a lot of powder avaliable to me at this time mine has a 14tw short heavy barrel an would like to do the 70 TNT experiment
so what would i load using varget or imr 4895... i have 7 1/2 rem br an lapau brass
reading your posts i should get some solid info.. i hope..!

thanks

 

[AckleymanII]

My partner and I shot untold thousands of the 70g TNT's in Hart barreled, 1-12 twist 243 AI's fireforming with 47-47.5g of Win 760 with a CCI 250 Primer with fireforming velocity at 3750+ shooting groups in the high 3's.

Formed loads were 48.0-48.5g of Win 760 at 3800-3850 depending on the barrel length and charge.

We NEVER had a problem with bullets not hitting the targets.

The 70g TNT's were so accurate, it made me feel stupid for having a very costly and time consuming set up to make 6mm Bullets, thus I sold the bullet making equipment.

 

[AckleymanII]

25AI260, In your 6 BR for the fastest velocity in a 6 BR, try AA2230, and with Benchmark, I am getting extreme accuracy, just about a max load so use a thick cup primer.

 

[sixfiveguy]

I have been using the Speer 70gr TNT's for a while out of a Tikka 243 and my Wife's 6mm Rem. The 243 load is using 39.7 gr of A-4064 shooting 1/4" to 3/8" groups. I have never driven them over 3800fps and they still hold up ok. 8)

 

[25AI260]

thanks keithcandler
if i can get AA ... i'l try it

i just realized i have a a pound of re 17... haven't found a use for it yet
how would that work in the 6br ... start load ? 14tw hb 70gr #1510 sierra ?

 

[Steve Blair]

My load development and QuickLOAD both indicate that RL17 is only suitable for heavy 6mm bullets. I would recommend it for 105-115 grain bullets. It looks like 50 ksi could only be achieved with a compressed load. It is likely that combustion would be sub-optimal.

 

[25AI260]

thanks Sleepyg, good timing with the info... i started to put 30.0gr w/ a .2+ latter tonite guess i'll pull those..

my next option is w748 ... i haven't shot the varget an imr 4895 yet but expect to when i visit the range on sat

like i mention in earlier posts get'n powder local is a problem .. when i find a workable one i'll order 8#'s i just hate get'n stuck with a bunch of partially
used 1 #'ers

 

[Steve Blair]

Rich,

I had never thought of using 748 for lighter bullets in 6BR. QuickLOAD predicts ~3500 fps from 26 inches and 70 grain Sierra with 35.0 748, 96.8 loading density and 57.5 ksi chamber pressure. Start at around 32.5 grains and work up in .3 increments.

I have about 4-5 pounds of 748 for .223 and will obviously have to try this in 6BR. Thanks.

 

[25AI260]

Great.. thanks, AM i will get on it..
i also have about 5#'s of the stuff for the 223..