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Copper bullets less precise than lead?


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Hello all. I just bought .270win Titan 6 (560mm,15mm,1/10) and i can not make it work with 130 grains GMX. Do you guys have same experience with copper bullets? I am asking, because in my CZ .308 i also could not make it work with e-tip from Nosler and GMX. I am trying to develop "lead free" hunting reload, but 2.5cm group on 100m is for me not that good. That is min group i could make with gmx. SD and es are good, 3shoots ,925ms avarage, ES:3, SD:1.7

 

Any advice on this one?

 

Regards

 

Ronzi

 

 

180731799_299555424913200_3949079636623395326_n.jpg

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how small are your target animals ?anything under 4cm will kill deer/fox etc at normal stalking ranges .keep tiny groups for range work they are not required for deer!

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How far are you jumping them out of interest?

I bought a box of factory Barnes TTSX ammo (130s) to try in my 308 yesterday, first 3 down the tube were probably the smallest 3 shot group I've ever shot with the gun.

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I have found that the rifle needs to be spotlessly cleaned and even then takes a little time to adjust to copper from lead. 
 

A bit like if you ever clean a .22rf it takes some time for the barrel to settle down. 
 

Hope this helps and seen this happen on two rifles now so don’t think it’s just me. 

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So, my max oal is 3.327 (84.54mm), i tried to reload at 3.210 (81.55mm) and 3.289 (83.55). Animals are wild pigs, deer, stag. I am not really satisfied with new gun to shoot 2.5cm group wit Lotherwalter barrel. I used to test N150, but i saw it has really high BA than normal. So my load was 50.4gr of N150 at 3.289, with nosler brass 70.9grains H2O, federal premium match LR primers and 130 GMX hornady. I have also option to pick RS70, RS60, N550 or N555.

My speed with this reload was 924ms - 3031fps avarage 

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  • 2 weeks later...

Yesterday i wanted to test lead bullets to see how is barrel and i tested Berger 150 vld hunting with RS70. You can see barrel is not problem. Lots of people is telling me that copper bullets are not that precised. What is your experience? 

 

905ms

150 VLD Hunting at 84.06mm coal

RS70

GM210M LP

Nosler case

 

185162212_966885237460274_9019028688585038487_n.jpg

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I've not heard that much good about GMX, but thats not to say they dont work. I tried a box of Barnes TTSX after their factory ammo shot well in my 308, I tried using a fast Viht powder as I reload another rifle with it.

barnes.jpg

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270, Barnes 110TTSX loaded to replicate/better Sako Powerhead 2 factory, so used fast powder, RS52, 53.0gr in once fired cases, produces 3250fps and cloverleaf/thumbnail groups out of my 22" barrel. No issues with accuracy.

However, not all barrels are as keen to play ball.

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On 5/12/2021 at 6:26 AM, ronzi83 said:

 Lots of people is telling me that copper bullets are not that precised. What is your experience? 

 

 

No issue here - consistent 1/3 MOA with copper (GS Custom bullets) and sub 1/2 MOA with Barnes TTSX.

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Interesting. I tought the like close to lands. Ok will try that. Next week i am getting box of 130 ttsx and trying to chose right powder. Was thinking to go new N555 or mayby i go with RS52. What do you say ? 

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  • 2 weeks later...

Mixed.

270 110gr TTSX early days in load development but looking like 3/4 moa minus, maybe 0.5 but not had enough rounds to confirm. Possible could match the current lead round.

308 130gr Fox - not so much a group as a pattern on a piece of A4. Worst grouping I have ever had out of any rifle by a mile. So bad I gave them away for free. BUT I see Venables got a decent group. Rifle shoots 0.5 moa+ so no idea what was going on. 

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With regard to the 30 cal 130s, I can assure you it's not inherent to the projectile. Zillions are used here, particularly through "Bushpigs" ( shortened suppressed carbines) and believe me, they group.

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  • 2 weeks later...

Hello. 

Today i tested 130 TTSX with RS62. You can see my data. Any idea where to load? 

starting from 56 with 0.2 grains increase each shoot. My OBT in GRT tools say should be 925ms, so shoots 5 if you see 4-5 and 6 are good vertical i think?

1: 56 - 915ms

2: 56.2 - 909

3:56.4 - 914

4: 56.6 - 920

5: 56.8- 925

6: 57 - 932

7: 57.2 - 941

8: 57.4 - 954

9: 57.6 - 947

 

20210605_202331_copy_2016x1134.jpg

graph.png

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Probably need to load a batch up of 3-5 of your preferred speed and then tune for best group. Copper bullets do need to be pushed hard to get best expansion . Field sports Britain did a good video of copper bullet reviews, it’ll be on you tube . There’s pictures on t web of expansion versus speed too . Good speed AND accuracy is what your after to get the correct expansion that matches the factory results . 
good luck 

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On 4/30/2021 at 2:16 PM, ronzi83 said:

Hello all. I just bought .270win Titan 6 (560mm,15mm,1/10) and i can not make it work with 130 grains GMX. Do you guys have same experience with copper bullets? I am asking, because in my CZ .308 i also could not make it work with e-tip from Nosler and GMX. I am trying to develop "lead free" hunting reload, but 2.5cm group on 100m is for me not that good. That is min group i could make with gmx. SD and es are good, 3shoots ,925ms avarage, ES:3, SD:1.7

 

Any advice on this one?

 

Regards

 

Ronzi

 

 

180731799_299555424913200_3949079636623395326_n.jpg

I know this is a pretty basic fact, but have you checked the gyroscopic stability (Sg) factor of .277" 130 gr GMX projectile from your rifle at the velocities you mention?

Going by the projectile's length that is given in QuickLOAD, which is listed as 1.330" (33.78 mm), the bullet is probably only marginally stable, this defined as an Sg of less than 1.4, but more than 1.0.

As such, at 3,031 fps from a rifle with a 1/10" (1/254 mm) twist barrel (as per the specs for a Titan 6 in 270 Winchester), the Sg of the GMX bullet is only 1.25.

Is the real problem, with your rifle and probably many others when using long for mass (i.e. lower denstiy) projectiles such as the GMX, the fact that your twist rate is too low?

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6 hours ago, ronzi83 said:

So i need to get speed up to get better stability? 

 

A lot.  You would need >10% more velocity to get into the recommended zone (JBM Stability calculator)

 

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1 hour ago, ronzi83 said:

Is this over max ok? It is next node from 925ms

Screenshot_9.jpg

Err, NO - on the face of it.  I suspect the rifle you have is not really optimised for the ammo you want to use.

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