I went to the range to do a barrel break-in for a new rifle. 29" Bartlein barrel chambered in 7mm RSAUM. Loaded 15 cartridges with 63 grains of H1000, magnum primers, and 180 gr Berger Hybrids. All cases were new, checked headspace, and had about 0.030 jump. First round gave me stiff bolt lift. (More effort than expected to open the action.) It also showed a bright spot that is associated with higher than normal pressures. So I was concerned I had inadvertently loaded to a maximum for my gun. Primer looked fine to me. So I fired another. No noted issues. I continued to shoot and clean for a total of 15 rounds. Round 14 had a bright mark but no bolt lift issue. And, case 15 had primer blow by, maybe pressure sign or a loose pocket. The odd thing is that all the cases show powder residue on the necks, none on the shoulders. If I had not experienced the bolt lift issue or seen the bright marks I would have suspected loads to be too low and not expanding the case neck. Before I go back out I'd like some input as to what you think may be going on. I plan to take the chrony for the next try and take just one or two rounds to see where I am velocity wise. There are two pictures included to help describe the results. Thanks in advance!
7mm RSAUM Fired Cartridge Results
- Thread starter cobbonthecorn
- Start date
COAL was about 3.1 as I recall. I don't have my notes with me right now.
Very interesting results. I've tested with H1000 and 180 hybrids and found around 65.0-65.5 grs work well with no pressure signs in my rifle, but close to max. I know every rifle is different, but I had the same problems happening to me with H4831 w/ 180's. Did you clean all oil out chamber after each cleaning? Do you measure the ejector marked case OAL? Just curious if they're to long and spiking pressure. Just some some things to think about.
Ahhhh! You got me thinking. If my ogive to base measure was in error and I'm sitting on the lands it may explain the conflicting observations. Tomorrow evening I am going to re-measure the chamber and verify the earlier measurements. Then if all checks out I am going to load 1 round with 0.100 jump. If I was on the lands before this should result in clean case necks. As someone noted, 65gr of H1000 is not unusual and of all the guns I have worked through I have not had a pressure problem starting 2 gr lower than reasonable loads. Will let you know how the experiment goes. Tks!
Since I'm going to the range I will also try a standard primer to see what happens....
I have seen some big variations in weight of new rem saum brass, generally between lots but also within a bag. I wonder if the cases with the plunger hole print have the same internal volume as the others. On another subject are rem actually still making new saum brass can you buy it readily in the USA? (I live in New Zealand and the stuff seems to be extinct here, everyone is using 300 norma necked down)
http://www.bullets.com/search?s=category%3abrass&s=cartridge:7mm+SAUM&o=1
I have about 500 of these cases and after fire forming in a custom chambering of the 7rsaum. Mostly just a steeper shoulder. Brass seems very consistent and I run them on the hot side, with 180s either with H4350 or IMR 7828ssc. Fed 215m primers.
Never had to try Remington brass. All I ever heard was that you needed a 500 lot to get 300 acceptable ones.
These are on sale right now
I have about 500 of these cases and after fire forming in a custom chambering of the 7rsaum. Mostly just a steeper shoulder. Brass seems very consistent and I run them on the hot side, with 180s either with H4350 or IMR 7828ssc. Fed 215m primers.
Never had to try Remington brass. All I ever heard was that you needed a 500 lot to get 300 acceptable ones.
These are on sale right now
Thank you for all the input. Went to the range today and ran another 0.070 off the lands. No pressure issues, running about 2800 fps, up to 63.1 gr H1000, and well under 0.5 MOA groups. Regular primer gave me about 25 fps more velocity for the one I shot. Now I can start the formal load development. Again, thanks!
The are 180 Berger hybrids. I was shooting a little high over the crony can probably get up to 65+ gr of powder, and get a little closer to the lands before its over. What do you think?
cobbonthecorn said:
I think the sweet spot for the 180gr hybrid and the 7 RSAUM is going to be in the 2890-2930fps Range. Lots of guys are going faster, but faster is not always better With the 180 hybrid.
Not sure if shooting higher on the chrony will read lower velocities.
If you can, maybe try h4831SC and maybe even h4350. H1000 is a good powder too. If you have issues with h1000, then maybe try one of the faster ones.
Tks! Agree on the velocity comment. I am only using velocity and velocity spread as indicators of variance.
cobbonthecorn,
Try working up the load first in 1/10th grain increments at the .070 off the lands first. If you don't find another velocity accuracy node before getting pressure signs your good. Let us know what you find.
Try working up the load first in 1/10th grain increments at the .070 off the lands first. If you don't find another velocity accuracy node before getting pressure signs your good. Let us know what you find.
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