6.5 Creedmoor Peterson Brass SRP

[Robo]

Recently picked up a few boxes of this brass to compare against the Lapua SRP brass I normally use due to seeing some good reviews and wanting to find a solid, US made precision option. After reading that this brand probably had a smaller interior capacity than my Lapua, I did some H20 testing that confirmed that this lot, which tested extremely consistent with <.6gr deviation in empty weight, did have about 1.3gr less H20 capacity than my current lot of Lapua.

I loaded up several ladders of H4350 for my AIAX using 147gr Hornady ELD, starting at 40.5gr and moving up to 41.8gr in .3 increments (I normally shoot 41.5gr using Lapua and get ~2750 fps with great accuracy in my 26" Bartlein barrel out to 1000+ yards). I loaded them straight out of the box given that they looked pristine in the way they ship, so didn't do anything from a resizing standpoint.

It was a cold, damp day up here in CT at 40 degrees so didn't expect to see blazing speed but was a bit surprised that even at 41.8gr H4350, I was below velocity of my normal Lapua loads, averaging 2744 fps with an SD of 3.7. I figured it was a combination of the neck tension of brand new brass and the weather.

I didn't get any flattening or cratering of my CCI primers, or hard extraction,

but noticed what looked like some extractor marks on several pieces, regardless of the load. It happened on a few of the lightest load. Not sure if this means anything but thought I'd get some input on whether this is a potential pressure issue or something else.

Appreciate some thoughts.

 

[PinesAndProjectiles]

Maybe a headspace issue? Do you have a comparator and any new brass?

 

[Robo]

Yeah, I have both. Guess I should measure it.

I measured some new Peterson brass against some new Lapua using my comparator and they're spot on identical. I also checked the headspace on my AIAX since I go back and forth between a .308 barrel and the 6.5 Creed (one of the many reasons I got this gun) using some Forster Go and No-Go gauges and that's good, too.

 

[PinesAndProjectiles]

I thought maybe the new cases were slightly shorter at the shoulder leaving excessive room in the chamber as when I first read the post, I read ejector, not extractor. But looking at the pic on my phone, is there ejector swipe? I'm having a hard time seeing it.

 

[Brentc]

I had excessive web expansion with moderate loads in virgin Peterson LRP brass in the creedmoor yesterday. Not sure what caused it. I was using 40.2 grains of RL16 with a 147 seated .040" off. The virgin brass spec'd out fine before loading.

I realize it's got quite a bit less capacity than Hornady brass, so I was expecting a smaller powder charge, but I wasn't expecting to see pressure signs at more than a full grain less than a comparable charge in Hornady brass. So far, I'm not all that impressed with it.

 

[Robo]

I thought maybe the new cases were slightly shorter at the shoulder leaving excessive room in the chamber as when I first read the post, I read ejector, not extractor. But looking at the pic on my phone, is there ejector swipe? I'm having a hard time seeing it.

That could be. Honestly, not sure how to tell extractor from ejector marks.

 

[PinesAndProjectiles]

Ejector marks usually are what looks like a high spot on the head of the case that’s much more shiny than the rest of the head. It is usually round as most rifles have a plunger ejector in the bolt face. You can see in the pic here a typical ejector mark on the 308 Lapua case. This is caused be either too much pressure in your case forcing the brass to flow into the ejector hole, or can also be caused when you bump your shoulders back too far with a sizing die, which creates excessive headspace.

 

[Robo]

Ejector marks usually are what looks like a high spot on the head of the case that’s much more shiny than the rest of the head. It is usually round as most rifles have a plunger ejector in the bolt face. You can see in the pic here a typical ejector mark on the 308 Lapua case. This is caused be either too much pressure in your case forcing the brass to flow into the ejector hole, or can also be caused when you bump your shoulders back too far with a sizing die, which creates excessive headspace.

thanks for the clarification and pic. The impression is not raised but looks more like a "swipe" or scrape. Hope the pic below makes is a bit more clear:

 

[PinesAndProjectiles]

Definitely looks like a swipe to me. It I’m not sure how you get ejector swipe in a bolt gun. I’ve seen it in an AR plenty of times, but never a bolt gun.
I’d try a Google search and see if anything come us. I’m curious now.

 

[Robo]

Definitely looks like a swipe to me. It I’m not sure how you get ejector swipe in a bolt gun. I’ve seen it in an AR plenty of times, but never a bolt gun.
I’d try a Google search and see if anything come us. I’m curious now.

I'll look around and see if I can find anything on this. Interesting that I've never seen this on my Lapua brass.

 

[30stones]

I had the same problem with my Peterson brass although it was not the SRP like you have. I had some swipe marks at 40.2. I emailed Peterson they told me they have less case capacity than hornady brass so therefore they told me you can achieve hornadys velocity with less powder. All my brass was first time fired. I did run them through they full length die but really I didn't need to do that.

 

[PinesAndProjectiles]

I defintely see that there is less case capacity in the Peterson brass. I am getting 3050 with 40.3 grains of H4350 in a 6 Creed.

 

[Robo]

Interesting. I did some H20 testing and it's clear that Peterson has less case capacity than Hornady and even Lapua. I kind of gave up trying to figure out the swipe issues and figured it was just the way it is with that brass since I had no other pressure signs and it wasn't a real hot load anyway.

What I am baffled about is that I get about 30 fps less velocity out of the Peterson SRP with 41.5gr H4350 than I do with the same load in Lapua SRP from my Bartlein 26" AI barrel. With the Peterson, I'm getting an average of 2740 and an average of 2770 with Lapua. I've tested it with new brass, brass fired multiple times and FL sized with Redding bushing dies and annealed using my AMP unit. The results remain consistent. The SD with Peterson is great, average around 6 with 10 shots, similar to Lapua, but I can't figure out why I get less velocity with brass that has less capacity. I would think the opposite would be true since, in theory, I believe the pressure would be higher? I'm using the same lot of powder and 147gr EDL-M for both.

 

[DetroitRearView]

I am running virgin Peterson 6.5CM SRP 44.4 4350 123 scenar CCI4450 9SD avg 2875 .2 -.3 in my SA AX .

I got a few swipes when doing OCW @ 43.5 grains, pulled my bolt and found a little bit crud between the ejector and the inside bolt edge. I cleaned the little bugger out and zero issues from then on.

Easy bolt, no more markings anywhere, primers just starting to flatten just outside the primer strike (SFP) bolt @ 44.4 and shooting fabulous in a 20" Proof.

 

[Robo]

I checked my bolt last time out and found some debris in there, too. Looked like tiny brass shavings, maybe from the swipes during past sessions. Cleaned it out and am not seeing much of an issue any longer. Getting good groups with single digit SD so guess I can deal with small swipes if they continue. Will be interesting to see how long this brass lasts. I'm AMP annealing after every shooting and up to 7 reloads. So far, so good.

 

[Clownbuster]

Interesting. I did some H20 testing and it's clear that Peterson has less case capacity than Hornady and even Lapua. I kind of gave up trying to figure out the swipe issues and figured it was just the way it is with that brass since I had no other pressure signs and it wasn't a real hot load anyway.

What I am baffled about is that I get about 30 fps less velocity out of the Peterson SRP with 41.5gr H4350 than I do with the same load in Lapua SRP from my Bartlein 26" AI barrel. With the Peterson, I'm getting an average of 2740 and an average of 2770 with Lapua. I've tested it with new brass, brass fired multiple times and FL sized with Redding bushing dies and annealed using my AMP unit. The results remain consistent. The SD with Peterson is great, average around 6 with 10 shots, similar to Lapua, but I can't figure out why I get less velocity with brass that has less capacity. I would think the opposite would be true since, in theory, I believe the pressure would be higher? I'm using the same lot of powder and 147gr EDL-M for both.

Robo, apologize if I missed this somewhere, but have you neck turned your Peterson brass to the same thickness as the Lapua brass? If not, what is the neck thickness of the Peterson?

 

[TN Shooter]

Robo, apologize if I missed this somewhere, but have you neck turned your Peterson brass to the same thickness as the Lapua brass? If not, what is the neck thickness of the Peterson?

I have not neck turned my Peterson brass and it is .293-.294 with bullet seated.

 

[Robo]

I haven't neck turned my Peterson brass either and the neck thickness is similar to what TN shooter is getting.

 

[BW64]

I had problems also with 6.5CM brass. Contacted Peterson & was told my pressure was too high & too much powder(40.2 IMR4451)compared to 42.2 in Hornady or Win brass @ 2730 fps. I checked the shoulders & they were way shorter than specs. Upon firing I had to beat the bolt handle to get the cases out. I don't run hot loads so I was not impressed. CS was very nice but..............................Anyway Win .308 brass seems to work best for me. I just resize & fireform to 6.5. If it lasts 3-5 firings it's worth the $$$.

BW

PS: brass was neck turned.

 

[Robo]

I had problems also with 6.5CM brass. Contacted Peterson & was told my pressure was too high & too much powder(40.2 IMR4451)compared to 42.2 in Hornady or Win brass @ 2730 fps. I checked the shoulders & they were way shorter than specs. Upon firing I had to beat the bolt handle to get the cases out. I don't run hot loads so I was not impressed. CS was very nice but..............................Anyway Win .308 brass seems to work best for me. I just resize & fireform to 6.5. If it lasts 3-5 firings it's worth the $$$.

BW

PS: brass was neck turned.

I'll be shooting a bunch of these in a few weeks and see how they look. I'm also on the fence with them and will probably stick with my Lapua stock going forward. I think you get what you pay for here.

 

[TIG_Man]

I am new here and this is my first post. While my background isn't in powders and reloading but rather thermodynamic's and I might be able to shed some light on the lower velocity despite lower case volume and same charge weight...

While yes, lower volume with the same charge weight should equally higher pressure but there are two different pressure aspects that have to be considered. Those two are 1, peak and 2, average.

Generally speaking, lower volume will increase peak pressure but peak pressure is not where velocity comes from... Velocity is strictly dependant on average pressure from the time the pressure is high enough to push the projectile out of the case to the time the projectile exists the muzzle.

This is why we can see some powders will give higher advertised peak SAMMI Chamber pressures and lower velocity with all else being the same. And on the flip side, other powders that will show a lower peak SAMMI Chamber pressure but higher velocities. Basically slower burning powders will give lower peak but higher average and thus higher velocity until you get to the point that its too slow and average drops too

Powder's burn rate (like fuel or any other accelerant) is going to be effected by the pressure. Higher pressure = faster burn... Faster burn = higher peak pressure BUT almost always lower average pressure and thus lower velocity.

With that said, the smaller case volume is likely causing the powder to burn faster so the peak is higher also but average has dropped. This would explain both the small loss in velocity and also the slight ejector swipes.

Lowering the charge by a couple 10ths of a grain quite possibly will get rid of the swipes and bring the velocity back up. Might even need a different powder.

EDIT: Scratch the "SAMMI" text and insert "Chamber".... No clue why I typed "SAMMI" each time...