6.5 saum pressure? adg brass?

[simmonzz]

Hey guys, I have a couple questions about what's going on after yesterday's shooting trip. I took out my brand new 16.5" 6.5 saum for the 2nd time to do some pressure tests and get velocity numbers. I know the common powders for the 6.5 saum seem to be h1k, rl26, etc. I don't however have those specific powders. I have imr 4350, hodgdon h4350, hodgdon h4831 and retumbo. I tried all 4 yesterday. I started at what I thought was on the lower side and worked my way up in 1gr increments. All of the loads tested were using:

- brand new adg 6.5 saum brass (no prep/nothing, seated primers, poured powder and seated bullets)
- hornady 143 eldx loaded .020 off lands and 2.220 cbto (didn't measure oal)
- cci 250 lrm primers

I tried:
52-55gr of imr 4350
52-55gr of Hodg. H4350
52-58gr of Hodg. H4831
55-60gr of Hodg. Retumbo

Everything hit pressure faster than I would've thought it would. Both the h4350 and imr 4350 had noticeable ejector marks at 55gr. The 4831 had an ejector mark from 54-58gr but the Mark never seemed to get any worse or better. And didn't have any heavy bolt lift. The retumbo had heavy bolt lift, ejector wipe, and very noticeable ejector mark at 58gr so I didn't shoot the hotter loads.

One thing I noticed was the lighter 4350s and 4831 loads all had quite a bit of room under the bullet so I'm not sure if they were too light causing pressure signs etc? All of the primers looked fine in fact they almost looked brand new aside from being fired obviously. The primers didn't flatten or anything. All pressure signs were found in the form of ejector wipes, ejector marks or heavy bolt lift.

Is there something I'm doing wrong? Has anybody else noticed this with the adg brass? What else should I be looking for? Etc if any of you want pictures or have additional questions I will try to clarify the best I can.

 

[dbohntr]

Failure to reduce charge weights established using other manufacturers brass will likely result in higher pressures and velocities while using ADG brass and may result in unsafe pressure levels.
I copied and pasted that from ADG.

I have a similar gun on order and will be using similar components .... so I am interested in what others have to say.

 

[Dmagna]

What r your speeds? Would be nice to know

 

[Mike D Texas]

Following.

 

[jraulsten]

Definitely need a slower burning powder.

I also learned the hard way that you don't use virgin brass for pressure testing and don't bother with it until your barrel is broken in (speeds up as much as it's going to). Otherwise all you do is trash a lot of your brass and go through a lot of components chasing your tail.

I typically end up putting about 100 rounds through my new barrels at mild loads, note if speed has increased and is staying constant, and then do the pressure testing if you want. At the first sign of pressure I back off a good bit and throw that piece of brass in the trash.

 

[simmonzz]

Failure to reduce charge weights established using other manufacturers brass will likely result in higher pressures and velocities while using ADG brass and may result in unsafe pressure levels.
I copied and pasted that from ADG.

I have a similar gun on order and will be using similar components .... so I am interested in what others have to say.

I know, ADG and everyone says the same thing. I wasn't trying to push the envelope right out of the gate. Like I'd said I was under the impression I was at the "starting" charge weights working my way up. With that being said though there is no load data for a 16.5" 6.5 saum. There's load data for 22-26" 6.5 saum and all of those guys seem to be running powders I don't have AND they seem to be runnin higher charge weights than I would feel comfortable shooting at this point in time with my current results. Only reason I was even trying faster powders like 4350 and 4831 is because of my short barrel.

What r your speeds? Would be nice to know

My speeds were anywhere from 2400-2760 which is nowhere near what I thought I'd be able to get out of this cartridge in this barre length. I was fully expecting to push the 143 eldx at around 2900-3k. The reason I thought I'd be able to obtain those velocities is because my 18" 6.5 creedmoor pushes the 143 eldx at 2690 with 41.6gr of h4350. So with an additional 13gr of h4350 in the 6.5 saum you'd think it'd be noticeably faster than 2690 not only 70fps faster

 

[Mike D Texas]

I know, ADG and everyone says the same thing. I wasn't trying to push the envelope right out of the gate. Like I'd said I was under the impression I was at the "starting" charge weights working my way up. With that being said though there is no load data for a 16.5" 6.5 saum. There's load data for 22-26" 6.5 saum and all of those guys seem to be running powders I don't have AND they seem to be runnin higher charge weights than I would feel comfortable shooting at this point in time with my current results. Only reason I was even trying faster powders like 4350 and 4831 is because of my short barrel.

My speeds were anywhere from 2400-2760 which is nowhere near what I thought I'd be able to get out of this cartridge in this barre length. I was fully expecting to push the 143 eldx at around 2900-3k. The reason I thought I'd be able to obtain those velocities is because my 18" 6.5 creedmoor pushes the 143 eldx at 2690 with 41.6gr of h4350. So with an additional 13gr of h4350 in the 6.5 saum you'd think it'd be noticeably faster than 2690 not only 70fps faster

You can't base results off what is seen in a totally different case design. Also there is no need to compensate with faster powders in a shorter barrel. Burn rate is burn rate.

The fat case of the SAUM needs a slower powder than the CM to get the best performance. That's why you were seeing early pressure signs And lower than expected velocities. I will tell you that 3k is a 16.5" barrel is likely not going to happen.

This is where a prediction software like Quickload or Gordons Reloading Tool is invaluable. If you shoot typical cartridges at SAAMI length there probably isn't much benefit. But playing around with wildcats and non-standard applications is where this software shines.

 

[simmonzz]

You can't base results off what is seen in a totally different case design. Also there is no need to compensate with faster powders in a shorter barrel. Burn rate is burn rate.

The fat case of the SAUM needs a slower powder than the CM to get the best performance. That's why you were seeing early pressure signs And lower than expected velocities. I will tell you that 3k is a 16.5" barrel is likely not going to happen.

This is where a prediction software like Quickload or Gordons Reloading Tool is invaluable. If you shoot typical cartridges at SAAMI length there probably isn't much benefit. But playing around with wildcats and non-standard applications is where this software shines.

Believe it or not lol but I don't own a computer because my phone basically does everything I ever need. I'd really like to try out Gordon's reloading tool but can't put it on my iPhone. If anybody has the time or wants to plug in all my info/data and see what it says that'd be greatly appreciated and welcomed. You could be totally right about 3k not being obtained out of my 16.5" barrel and I wouldn't be surprised if that was the case I might have had too high of expectations for those velocities out of a copper/lead bullet. Those velocities might only be obtainable with a mono which I'd be fine with running as well just hadn't tried any hammers out of this rifle yet. I need to order some.

 

[Mike D Texas]

Believe it or not lol but I don't own a computer because my phone basically does everything I ever need. I'd really like to try out Gordon's reloading tool but can't put it on my iPhone. If anybody has the time or wants to plug in all my info/data and see what it says that'd be greatly appreciated and welcomed. You could be totally right about 3k not being obtained out of my 16.5" barrel and I wouldn't be surprised if that was the case I might have had too high of expectations for those velocities out of a copper/lead bullet. Those velocities might only be obtainable with a mono which I'd be fine with running as well just hadn't tried any hammers out of this rifle yet. I need to order some.

With 4831 your speeds are in line with QL predictions. Like I said it pressures out way early. See attached powders list from Quickload. Unfortunately your 16.5" barrel really isn't doing you any favors.

 

[simmonzz]

With 4831 your speeds are in line with QL predictions. Like I said it pressures out way early. See attached powders list from Quickload.

Greatly appreciate that. The 4831 seems in line but the retumbo was quite different. Had heavy bolt lift, ejector wipe and Mark at 58gr and that pdf says 62.2gr

 

[Mike D Texas]

Greatly appreciate that. The 4831 seems in line but the retumbo was quite different. Had heavy bolt lift, ejector wipe and Mark at 58gr and that pdf says 62.2gr

Not knowing your actual COAL I had to go with SAAMI. That may or may not be accurate depending on your OAL.

Something is off though because with Retumbo you should have been 20K psi under max pressure.

I ran predictions with 123 Absolute Hammers as well and the powders you have on hand are leaving a lot on the table.

 

[simmonzz]

My coal was 2.8620. That gives me a .020 jump

 

[simmonzz]

Not knowing your actual COAL I had to go with SAAMI. That may or may not be accurate depending on your OAL.

Something is off though because with Retumbo you should have been 20K psi under max pressure.

I ran predictions with 123 Absolute Hammers as well and the powders you have on hand are leaving a lot on the table.

My coal is measuring 2.8620 when I measure 2.220 to the ojive. I'm currently getting a .020 jump when I compared to my jam measurement

 

[Mike D Texas]

Slightly longer cartridge length helps a few fps but not really much. SAAMI length is 2.825.

RL26 is pretty much magic in most 6.5mm cartridges if you are chasing velocity. Unfortunately it's nearly impossible to find.