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Load testing LRP vs SRP with terrible results

6Creed73

I've been using LRP for 6CM for years and I have some great loads for it in my load book. However, since getting LRP is getting more and more difficult, I decided to do some testing with SRP....all I can say is YUCK! The ES/SD with the SRP was horrendous.

I took my 4 favorite loads and loaded up 10 LRP and 10 SRP for each of the 4 loads. The LRP were CCI 200 and the SRP were BR 4. Everything else was identical, including the brass - both Alpha. These were all loaded with H4350.

Here are the comparisons for each Load. Velocity was a bit slower for SRP as well. If anyone is having success with SRP in 6CM or similar which SRP are using? Have you found one powder that seems to work better with SRP?

LRP:
1. ES - 16, SD - 5
2. ES - 14, SD - 7
3. ES - 26, SD - 9
4. ES - 31, SD - 11

SRP:
1. ES - 46, SD - 17
2. ES - 44, SD - 16
3. ES - 55, SD - 17
4. ES - 58, SD - 19
5. ES - 68, SD - 23
 
Last edited:
gqhoon said:
Agree that you really need to build the SRP load up from scratch in order to make a fair comparison. I use CCI450’s in a 6CM also, below is from a quick velocity confirmation as I walked out the door to the last match.
Click to expand...
Damn, those number are great. I usually get my ES/SD with 10 shots, but still...impressive. Want to share the load details? ;)

Yeah, I will work up some loads. I was curious how they'd perform with my current loads. I got my answer.
 
6Creed73 said:
Damn, those number are great. I usually get my ES/SD with 10 shots, but still...impressive. Want to share the load details? ;)

Yeah, I will work up some loads. I was curious how they'd perform with my current loads. I got my answer.
Click to expand...
Totally agree, a 10-20 shot string will give an SD that is more reflective of the load‘s actual performance. 39.5gr of RL16 and Berger 105Hybrid.
 
A suggestion, start walking the powder charge to hit the same velocity you enjoyed with the lrp. It will take bit more and the SD should come back in line.

We're the sr cases being fire formed? I find the Sr primers to be more picky about seating the first time. Just me and my ocd peeking out.
 
mgunderson said:
A suggestion, start walking the powder charge to hit the same velocity you enjoyed with the lrp. It will take bit more and the SD should come back in line.

We're the sr cases being fire formed? I find the Sr primers to be more picky about seating the first time. Just me and my ocd peeking out.
Click to expand...
Both the LRP and SRP were once fired in my chamber and neck sized. I got lucky and found 1000 CCI 450's locally and will be picking them up tomorrow. Then, like you mentioned, I'll load some up to do some ladder testing.
 
mgunderson said:
There are many examples of good srp brass above the 35 to 40 gr area. Palma brass or 308 srp is one of the better examples. Low temps and powder selection are important. I applaud the oringinal poster for making decisions based on data and not just quote others.
Click to expand...
I'll note that in the larger cases with srp's mostly use a lighter bullet
with faster powders like Varget or R-15 / 15.5. In the case of his
6-CM, looks like H-4350 may be the culprit with that large of a dose
of powder, with a small primer. Just speculating though as I have no
real experience with Palma cases other then using them to wild cat
a close copy of the 30x47 with 35 degree shoulder.
 
You need to re-do your load workup when switching primers for a valid consensus.

Several years ago, I did a similar test with one of my 6x47 Lapuas. I already had a great load with 7 1/2's to compare to, so I used a stash of my old 30x47 Lapua 308 LRP brass & converted them to 6x47 Lapua.

When the smoke cleared, I could also get the brass with 210's into single to low double digit ES, but none were with the same loads as with the 7 1/2's.

Accuracy wise, the 210's had a slight advantage as well.
 
I have Staball 6.5 and RL16 as well. When I get a chance I'm going to test both of those to see if the issue I'm seeing is with H4350, at least with 41gr of it.

I can also back the H4350 down below 35gr, but I'd never use that as a load so it would just be a test.
 
6Creed73 said:
I've been using LRP for 6CM for years and I have some great loads for it in my load book. However, since getting LRP is getting more and more difficult, I decided to do some testing with SRP....all I can say is YUCK! The ES/SD with the SRP was horrendous.

I took my 4 favorite loads and loaded up 10 LRP and 10 SRP for each of the 4 loads. The LRP were CCI 200 and the SRP were BR 4. Everything else was identical, including the brass - both Alpha. These were all loaded with H4350.

Here are the comparisons for each Load. Velocity was a bit slower for SRP as well. If anyone is having success with SRP in 6CM or similar which SRP are using? Have you found one powder that seems to work better with SRP?

LRP:
1. ES - 16, SD - 5
2. ES - 14, SD - 7
3. ES - 26, SD - 9
4. ES - 31, SD - 11

SRP:
1. ES - 46, SD - 17
2. ES - 44, SD - 16
3. ES - 55, SD - 17
4. ES - 58, SD - 19
5. ES - 68, SD - 23
Click to expand...
Just curious and perhaps a foolish question but, even though the case brand was the same was the case volume the same?
 
hmcsr said:
Just curious and perhaps a foolish question but, even though the case brand was the same was the case volume the same?
Click to expand...
I can only assume as I didn't do a case volume measurement. But the brass is from the same lot and were fired in my chamber, then neck sized only.

I highly doubt that's the issue. More likely what others have said. I need to work up loads for SRP to see what performs best with them. And I think the magnum primers will help vs BR4.
 
6Creed73 said:
I have Staball 6.5 and RL16 as well. When I get a chance I'm going to test both of those to see if the issue I'm seeing is with H4350, at least with 41gr of it.

I can also back the H4350 down below 35gr, but I'd never use that as a load so it would just be a test.
Click to expand...
I doubt it’s the H4350 that’s creating the issue. It’s available here as AR2209 and is probably one of the most commonly used powders in NZ / AU. I’m using it in my 6GT and getting similar results to the RL16 in the 6CM
 

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