swiss reload, velocity consistency, primers

[ai308]

Hi guys,

I'm new to ukvarminting.com and I'm pretty lucky that I found that page. Overwhelming knowledge, I couldn't stop reading.

I hope, my 1st post will not be a redundant one.

 

I've  changed the powder for my .308 from N140 to RS50 and RS52 some weeks ago. However, I'm not happy with the SD of the velocities I've achieved so far.

Best results:

• SD of 13 (5 shots,44.4gr RS50)
• SD of 11 (5 shots, 44.6gr RS52)

Besides of that, the SD was between 20 - 30 for the other loads (43.5 - 44.2)

I'm using the following components:

•  Lapua .308Win brass ( fired 3 times so far)
•  Hornady 168gr HPBT match
•  CCR BR2 large primer

Tried Neck-sizing as well as FL, Did not change the results much. Best consistency was around 44.4 gr (RS50) and 44.4 - 44.6 gr(RS52).

But I've recognized, that I've got some neck tension issues. (inconsistent pressure when seating the bullets) This needs to be fixed, before I should do further testing.

 

But just for interest, what SD do you achieve with RS 50 / RS 52 and Lapua .308 brass?

What primers do you use?

 

[Incisor]

I moved from Lapua brass to weight sorted ggg brass and in my rifle 43.8gr of rs52 gives me 2749fps with sd of 7.2 with 175 scenar L and Murom primers

regards

[No i deer]

I was watching ftr shooters yesterday from 300 to 600yds running on RS52 with their loads and it looked pretty good to me.very accurate powder weighing and neck tension are the key factors it seems.

[Malxwal]

I have been running RS52 in my 308, stalking loads under light bullets, but still checked. Neck tension too was my issue, shifting to a more tightly controlled batch of brass helped tighten things up.

[VarmLR]

I've been using RS50 in mine with 175 TMKs and Lapua brass with Murom primers, and achieving good SD and low ES.

Try using OCW or Satterlee load development as it helps identify your lowest SD loadings with better precision and efficiency than ladder testing.

Neck tension needs to be consistent, but unlike smaller cals such as 223 I have found no need to brass batch to achieve low SD or the use of any fancy dies with my .308 as once a node is found, it tends to be reasonably pressure insensitive to a .5gr spread.  I use a Lee FL die, a Lee factory crimp die and I anneal every single firing.  I simply load to mag length and seldom bother chasing the lands as there's little need with the bullet designs that I use.

[ai308]

Sounds good! Thanks a lot. Hope, I'll do my homework right and get consistent neck tension afterwards.

[ai308]

Btw, what are the best SD values you were able to achieve with RS50, RS52 powders? fps or m/sec?

I've just recognized, that my buddy measures in m/sec but I'm using fps.

After having done some further load development, I was able to achieve an SD of 10-12 fps with 44.6gr RS52 behind a 168gr Hornady HPBT. But only 2/10gr (+ or -)  away from that, the SD just doubles.

Using RS50, the best result I could achieve with the 168gr Hornady HPBT has been a SD of 14 fps at 44.4gr. But the 2nd day I fired the rest of the rounds loaded with the same parameters, I've got values between 25 fps and 36fps SD. 

 

 

[No i deer]

Do you me ES or SD

[ai308]

3 hours ago, No i deer said:

Do you me ES or SD

SD.

[Catch-22]

I had these issues with my previous 6.5x47. Original load was N140 ignited by a CCI450 primer. ES/SD were shocking, all over the place - though accuracy was fairly good!

As soon as I switched from the CCI450 to the Murom KVB223m primer, both my ES & SD shrank to single digits and stayed there. I changed nothing else in my reloading procedure. 

[No i deer]

.My 47 shoots single digit ES,s on CCI BR4's using 123gr amaxs.140gr amax and 139gr scenars.i am not getting that with my 7mms at the mo.i am trying too.i use muroms sellor and belliot and CCI BR2's.the load probaly needs dropping to achieve them.accuracy is good so I will leave it until temps are lower which I guess will contribute to this too.