300wm rl26 help with pressure signs
- Thread starter unclefish
- Start date
Help Support Long Range Hunting Forum
coyotezapper
Well-Known Member
What is your OAL and bbl length?
Measuring case head expansion one the belt can assist in identifying excessive pressure. Measure and record belt diameter prior to firing and compare to after firing. A 0.0005" case head expansion in a single firing is about your pressure limited powder charge, unless you want to lose primer pockets in a couple of firings.
0.002" expansion on the belt with a single firing means you're running them pretty hard. You won't get many reloads on that brass before you lose the primer pockets due to case head expansion/primer pocket expansion.
I like to keep the belt expansion on my 300 Win Mag brass to 0.0005" or less with a single firing on new cases.
How about the 71-73gr loads?
I like to keep the belt expansion on my 300 Win Mag brass to 0.0005" or less with a single firing on new cases.
How about the 71-73gr loads?
MagnumManiac
Well-Known Member
- Joined
- Feb 25, 2008
- Messages
- 5,588
You cannot measure case head expansion ACCURATELY with calipers. You can ONLY measure case head expansion with a blade type micrometer that reads to .0001" accuracy.
Primer appearance is also not a good way to guage pressure, either.
As pressure increases, you will get expansion lower on the case, if you take note of this and see ANY increase in bolt lift, back off from that point.
I would increase in 1gr increments until I got slightly harder bolt lift, back off 1gr from that point and call that the rifles max.
It is also very likely you will get an accurate load somewhere less than max pressure.
If you are single loading to check for pressure, this is not a great way to do this. You should be loading at least 3 charges in each weight, shoot them over a chrony and for groups all in one hit, this will actually save components and barrel life.
Hope this helps.
Cheers.
gun)
coyotezapper
Well-Known Member
Too close to the lands for a solid. It is important that you go by Barnes recommendations when it comes to seating depth. I would seat at .050" ( 3.531" )jump and then find your powder node then fine tune with seating depth and be done.
I wish I had known that for the past 15 years. I need to ask why one needs a measuring device scaled to 0.0001" when measuring 0.0005" is sufficient for the task at hand?
I confidently conclude you've never spent any amount of time monitoring case head or belt expansion. Because I will ALWAYS detect 0.0005" belt expansion before I obtain heavy bolt lift, even with Lapua 300 Win Mag brass. The straightforward and logical conclusion? If you believe stiff bolt lift is a good indicator of high pressure, you should feel that 0.0005" belt or case head expansion is a great indicator.
I've been consistently measuring case head expansion for indications of high case pressure with calipers graduated to 0.001" with functionally sufficient accuracy for a long time now. A blade type micrometer or another measuring device graduated to 0.0001" would also work (I've never used one for this purpose), but they are unnecessary when the goal is to detect expansion of 0.0005".
It's easy to detect 0.0005" with Mitutoyo dial calipers graduated to 0.001". It's even feasible to detect 0.00025" with my 0.001" graduated dial calipers. If I had dial calipers graduated to 0.0001", I could easily detect changes to 0.00005". Being able to measure to 0.00005" serves my purpose no better than being able to measure to 0.0005".
I wouldn't be messing around 0.005" from the lands either. Why risk some bullets contacting the lands and causing pressure spikes. Back 0.010" off at a minimum to help ensure all bullets are clear of the lands. If Barnes recommends more, so be it. But taking the chance of some bullets contacting the lands and others not by seating so close to the lands isn't advisable.
does it tell you in barnes #4 manual about being .050 off the lands . I looked briefly this morning before I headed to work. or do you need to call them for that info. I didn't know about this. Is there anything else with using these 200gr lrx bullets I should know. thanks for help. I will get a crony reading this weekend hopefully if weather holds out.
also I went back down to loading room this morning and I rechecked all 3 cases that I fired from each powder group with the little blade part of my mitutoyo calipers and most of all do read .001 large than a new case. my primary focus is hunting . I would like to shoot out to 1000 yards one of these years but I need more experience. even if I had to buy an extra 100 to 200 cases a year and a new barrel ever 5 years. it wouldn't bother me. just want the confidence that every time I pull the trigger I know where that bullet will hit.
Re: 300WM RL26 help with pressure signs
I searched for a while yesterday in the attempt to find some published RL26 load data for the Barnes bullets. I didn't find any. Don't know if you have load data for RL26 or not? If so, what does it show for starting and max powder charges?
If your belts expanded 0.001" or more on the first shot fired, it doesn't mean they've damaged, or will damage, your rifle. It means your pressures are getting up there. It would be a good time to obtain some chronographed MVs to see where your at, compared to published Max load velocities for Barnes 200gr bullets.
Your belts may not expand another 0.001" with a second firing. They seem to toughen up a little after the first firing, however when I get 0.001" and more on a single firing, I usually have to back off. After they expand 0.003" or more, the primer pockets may no longer hold primers and may become leaky. I've never used Norma 300 Win Mag brass, but I read it is pretty good brass - with good case head strength. If your belts continue to expand with the second and third shots, then no matter what the reloading manuals are printing, your load in your rifle is likely excessive - pressure wise.
I searched for a while yesterday in the attempt to find some published RL26 load data for the Barnes bullets. I didn't find any. Don't know if you have load data for RL26 or not? If so, what does it show for starting and max powder charges?
If your belts expanded 0.001" or more on the first shot fired, it doesn't mean they've damaged, or will damage, your rifle. It means your pressures are getting up there. It would be a good time to obtain some chronographed MVs to see where your at, compared to published Max load velocities for Barnes 200gr bullets.
Your belts may not expand another 0.001" with a second firing. They seem to toughen up a little after the first firing, however when I get 0.001" and more on a single firing, I usually have to back off. After they expand 0.003" or more, the primer pockets may no longer hold primers and may become leaky. I've never used Norma 300 Win Mag brass, but I read it is pretty good brass - with good case head strength. If your belts continue to expand with the second and third shots, then no matter what the reloading manuals are printing, your load in your rifle is likely excessive - pressure wise.
