I had some pressure spikes in 7 Rem mag just as described in the OP's first post and when I got to the bottom of it was only after checking H2O capacities of Nosler brass and found that I had as much as 6-7 grains difference in interior H2O capacity in some cases and bit more than that in differing lot #'s. That can bite you on pressure and velocity changes.
.28 Nosler Pressure
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I had some pressure spikes in 7 Rem mag just as described in the OP's first post and when I got to the bottom of it was only after checking H2O capacities of Nosler brass and found that I had as much as 6-7 grains difference in interior H2O capacity in some cases and bit more than that in differing lot #'s. That can bite you on pressure and velocity changes.
Coyote Dan
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don't want to change your mine , I love my 28, just wish I had more of my original powder, seems like others are at 86-87gr R-33 and Im down to 82gr. Its still flatter shooting than most, till you get to the big 338s pushing 300s over 3000fps. Don't know of any other brass, Nosler is suppose to be as good as Lapua. Retumbo also shoots very good in it , just went to R-33 trying for more speed. If you build one you will love it. 195gr. Berger .755 BC. Hard to beat. Good luck
coyotezapper
Well-Known Member
All of you that are having brass issues seem to be ignoring the fact that you may be over pressured. Those that are using 86-87 grains probably may have a longer freebore and can therefore run more powder and get a little more velocity. If you are running a saami spec .188" freebore your rifle will be prone to over pressure at a lower powder charge. Like I have stated above I have used Nosler / Norma brass in 7STW and 7RUM with no issues and I have a hard time believing that all of the 28 Nosler brass is flawed. Have you asked your smith what your freebore is???
I just went and weighed my 28 Nosler brass - 100 pieces and it is well within spec weight wise. Mine was purchased in 2015.
I just went and weighed my 28 Nosler brass - 100 pieces and it is well within spec weight wise. Mine was purchased in 2015.
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Nosler brass for 7 Remington Magnum:
In March 2015 purchased 100 Nosler brass, was excellent quality and weighed 215 grains average.
Also had some much older Norma brass that weighed 218 grains. I could load interchangeably either brass with no noticeable difference in speed or accuracy.
In March 2016 purchased 100 Nosler brass and opened them couple months ago to load and the first one I loaded I crunched powder at seating. This caused pause to check brass. Found this batch weighed 256 grains average.
Head stamp was different also. Don't remember which was which but one was stamped 7MM and the other lot was stamped 7mm clearly from different manufacturers.
In March 2015 purchased 100 Nosler brass, was excellent quality and weighed 215 grains average.
Also had some much older Norma brass that weighed 218 grains. I could load interchangeably either brass with no noticeable difference in speed or accuracy.
In March 2016 purchased 100 Nosler brass and opened them couple months ago to load and the first one I loaded I crunched powder at seating. This caused pause to check brass. Found this batch weighed 256 grains average.
Head stamp was different also. Don't remember which was which but one was stamped 7MM and the other lot was stamped 7mm clearly from different manufacturers.
trailrider121
Well-Known Member
Very good information regarding pressure and and brass life. High nodes really take a toll on brass. Lower nodes seem to do well and with 195's great BC its hard to beat.
I am a bit lost after reading thru this.
Are you guys getting the right vel for a higher powder charge but just do not like the fact that others are using more powder to get the same vel?
I get it if you are getting say what the reload manual states is a min charge and the vel that goes with it and are seeing pressure issues but if the vel is where it should be at a higher charge than you use vel as your indicate. As has been said psi is directly related to the pressure curve.
I get that the change in one barrel goi g from needing 3 gr more to needing 3 gr less for the same vel lea es a big???
My thought are break down what can change.
If your cleaning the barrel it will not be the cuase
Are you using the same brass?
Did you trim all to the same length and check h2o capacity when new and then now you are having issues? If its new brass compare to the old. Maybe your fl sizing is actually taking it down so much below new its costing capacity.
Is it the same lot of powder and was it kept in the same stable enviornment the whole time?
Bullets crom the same lot? Measured bearing surface diameter and compare?
My gut says its the brass.
Also after the first firing if you are still having to trim necks each firing or two the brass is being pusbed too hard. Brass only flows when its pushed past the point of it yeild stength by a large margin.
I would be getting some new nosler brass. Throw out any extremely short ones then trim the others to the shortest length of the mean group. Weight them and sort. Then test h2o capacity for each group. Load say 3. Fire. Check h20. Resize and check h20 again. Load again and fire. Keep repeating say 3 to 5x.
You can also compare to others what their h20 capacity is for a case length. The compare their charge amount for thag specific load and see how it compares.
Case marks are one of the worst ways to gauge pressure. If you were perfect with the same brass and firings etc where everythi g could be consistent it could get you ball park maybe. Anyone with pressure testing equipment will tell you the same thing. While strain gauges can be consistent they must be calibrated on each barrel to give absolute pressure but still great. Piezo and referance powder loaded ammo still has to be used to do it right.
My bet is case capacity changed. If its not that next would be powder lot burn rate change. Next bullet diameter.
I say start with new cases and docume t everything. Keep the lot size small so you are not wasting barrel life and money.
Are you guys getting the right vel for a higher powder charge but just do not like the fact that others are using more powder to get the same vel?
I get it if you are getting say what the reload manual states is a min charge and the vel that goes with it and are seeing pressure issues but if the vel is where it should be at a higher charge than you use vel as your indicate. As has been said psi is directly related to the pressure curve.
I get that the change in one barrel goi g from needing 3 gr more to needing 3 gr less for the same vel lea es a big???
My thought are break down what can change.
If your cleaning the barrel it will not be the cuase
Are you using the same brass?
Did you trim all to the same length and check h2o capacity when new and then now you are having issues? If its new brass compare to the old. Maybe your fl sizing is actually taking it down so much below new its costing capacity.
Is it the same lot of powder and was it kept in the same stable enviornment the whole time?
Bullets crom the same lot? Measured bearing surface diameter and compare?
My gut says its the brass.
Also after the first firing if you are still having to trim necks each firing or two the brass is being pusbed too hard. Brass only flows when its pushed past the point of it yeild stength by a large margin.
I would be getting some new nosler brass. Throw out any extremely short ones then trim the others to the shortest length of the mean group. Weight them and sort. Then test h2o capacity for each group. Load say 3. Fire. Check h20. Resize and check h20 again. Load again and fire. Keep repeating say 3 to 5x.
You can also compare to others what their h20 capacity is for a case length. The compare their charge amount for thag specific load and see how it compares.
Case marks are one of the worst ways to gauge pressure. If you were perfect with the same brass and firings etc where everythi g could be consistent it could get you ball park maybe. Anyone with pressure testing equipment will tell you the same thing. While strain gauges can be consistent they must be calibrated on each barrel to give absolute pressure but still great. Piezo and referance powder loaded ammo still has to be used to do it right.
My bet is case capacity changed. If its not that next would be powder lot burn rate change. Next bullet diameter.
I say start with new cases and docume t everything. Keep the lot size small so you are not wasting barrel life and money.
coyotezapper
Well-Known Member
I have been loading the 7STW - twin brother to the 28N for 20ish years and have now loaded for the 28N in 4 different rifles and there are a few things that I have seen that impact pressure. Case capacity, powder burn rate, seating depth - jammed bullets and to a somewhat lesser degree primers and barrel twist.
In the 28N I have seen 8 twist barrels seem to show pressures signs earlier but can still get the max velocity wanted if velocity is what you are chasing.
My 7STW never had brass issues with hot loads but I attribute this to the belt. I still have some of the original Remington brass from their first factory loaded rounds. This being said I have had no issues with any of Nosler/Norma 28N brass but all of my load work up was originally done with pressure testing equipment so I know the limitations of the brass within reasonable pressures. With all 28N rifles the brass lot numbers were different but I have been able to get the same results with safe pressures out of all of them. The brass is very good quality. I even have used necked up 26N brass and have the same results.
My biggest problem with this subject is that some refuse to accept the obvious. If the brass is going south, this is a handloading/pressure problem and not a brass quality issue IMO. I steered away from another thread because the poster could not understand why his brass lasted only 2-3 firings when he was running the 195 Berger at 3300 FPS. He claimed this was a load that was safe and used by many. My burn rates taken from different lots of R33 showed this load to be around 75-80K if shot through my rifles at this velocity.
A little off subject here but worth mentioning is powder used in the 28N. I love Reloader powders. They have always given me the best performance but have always been temperature sensitive. R33 is no different. I have not quite figured it out yet but it seems to be very stable at one velocity/pressure and then be unstable at another. Still gathering data with no clear conclusion yet. For this reason I use Retumbo for my working load. Its a little slower but very stable across a wide temperature range.
In the 28N I have seen 8 twist barrels seem to show pressures signs earlier but can still get the max velocity wanted if velocity is what you are chasing.
My 7STW never had brass issues with hot loads but I attribute this to the belt. I still have some of the original Remington brass from their first factory loaded rounds. This being said I have had no issues with any of Nosler/Norma 28N brass but all of my load work up was originally done with pressure testing equipment so I know the limitations of the brass within reasonable pressures. With all 28N rifles the brass lot numbers were different but I have been able to get the same results with safe pressures out of all of them. The brass is very good quality. I even have used necked up 26N brass and have the same results.
My biggest problem with this subject is that some refuse to accept the obvious. If the brass is going south, this is a handloading/pressure problem and not a brass quality issue IMO. I steered away from another thread because the poster could not understand why his brass lasted only 2-3 firings when he was running the 195 Berger at 3300 FPS. He claimed this was a load that was safe and used by many. My burn rates taken from different lots of R33 showed this load to be around 75-80K if shot through my rifles at this velocity.
A little off subject here but worth mentioning is powder used in the 28N. I love Reloader powders. They have always given me the best performance but have always been temperature sensitive. R33 is no different. I have not quite figured it out yet but it seems to be very stable at one velocity/pressure and then be unstable at another. Still gathering data with no clear conclusion yet. For this reason I use Retumbo for my working load. Its a little slower but very stable across a wide temperature range.
I am at 81.5 gr of rl33 and getting 3020fps. Brass is still getting beat up pretty good. I look at some of the loads being shot, and my mind is boggled! Certainly some are shooting 195's on the ragged edge. I believe my rifle is still getting quicker and will be dropping a half gr soon.
Anyway pressure trace is being glued in now, should have some solid numbers tomorrow.
On another note it did take my daughters first whitetail at just shy of 400 yrds last weekend. Bullet did an amazing job.
Anyway pressure trace is being glued in now, should have some solid numbers tomorrow.
On another note it did take my daughters first whitetail at just shy of 400 yrds last weekend. Bullet did an amazing job.
coyotezapper
Well-Known Member
I am assuming 195 Berger???
What is your freebore and what is your jump. Jam will cause an initial pressure spike and may be what you are seeing.
trailrider121
Well-Known Member
I just work up a load using 195's in my 28 Nosler. I was using 180 Scenars for half the year, and wanted to try the 195's out. My chamber is saami spec with .180FB. My 195's coal is 3.641". I found a load of 85.6grs RL-33, .030" OTL, using fed 215m in 26 Nosler brass. My speed is 3040 avg with 26" barrel and getting great groups. My barrel is a 1:9 twist and is stabilizing them well to 300 yards ( farthest I've tested) at 200-2000' asl.
Toliver, I don't know why such a low charge, maybe you have a carbon build up? Or maybe a hot lot of RL-33 powder.
Toliver, I don't know why such a low charge, maybe you have a carbon build up? Or maybe a hot lot of RL-33 powder.
coyotezapper
Well-Known Member
These are good solid, safe numbers which I have duplicated in each of the rifles I have worked with. Everyone needs to take note of this load.
Not sure what's going on with Tolivers load. Maybe just a fast lot of powder. I would not worry about the charge and just stay with the velocity target of around 3000 fps and pressures should be fine.
Toliver if you get a chance measure your case capacity and post it here.
Yes I will measure capacity. We are also going to run pressure traces on it today just to get a better idea of the actual pressure. Who knows whats going on. Gun is clean, I did notice my brass is at the minimum dimension's listed by SAAMI. Its a new SAAMI spec reamer, and throat was cut long after. I'll post the pressures hopefully this afternoon. I'm not to worried about it, I'll just keep the velocity's around 3000, it shoots small groups there anyhow. I just think it will be insightful to test it, I'm not a fan of using brass as an indicator of pressure. Lab radar is much better, couple that with the trace even better. Who knows maybe I'll discover I'm running a little light. I was using like 77 grns Retumbo same results.
jweigel
Well-Known Member
I know its not the same caliber...but very close case using the same bullet. https://www.longrangehunting.com/threads/7stw-refresh.191205/#post-1343198
If you have not giveen VIT N570 a try you should. I am getting 3098 FPS out of 78 grains of N570. Several grains below pressure. I validated the speed out to 800 yards and the drops were spot on.
I am .030 OTL with a COAL of 3.900. I have a 4" Wyatts box. This is in a 7STW incase you missed that.
Makes for a powerful setup.
jjw
ND
If you have not giveen VIT N570 a try you should. I am getting 3098 FPS out of 78 grains of N570. Several grains below pressure. I validated the speed out to 800 yards and the drops were spot on.
I am .030 OTL with a COAL of 3.900. I have a 4" Wyatts box. This is in a 7STW incase you missed that.
Makes for a powerful setup.
jjw
ND
