Pressure?

[Jeffrey Van Zandt]

Hello everyone. Need some help here. I have shot 3 loads today at the range, and all three caused some sticky boat lift. I don't feel like the power charge is that high, and I'm not good at telling pressure signs by looking at the bottom of the case. In my 7RM. Thanks

Understanding Pressure :: Primal Rights, Inc

Reading pressure is a required skill that all shooters must have. Whether you are shooting factory ammunition or your own handloads, you absolutely must be able to detect and interpret pressure signs on your fired brass.

www.primalrights.com

 

[VTbluegrass]

I ran 162 ELX and 168 Berger's in a 7RM Montana Rifle Company X2 both over 70grs of H1000 right at the top of book values. Speed would tell you alot if you are over pressure. Mine drove me crazy because I had nice round primers, no ejector marks, but I had craters. Ended up the firing pin hole needed bushing, there was actually enough space forPrimers to have a crater appearance 3 grains off max. That gun only shined at the top end too.

That 66gr of H1000 data is for a 160 partition and they always have low book value. Warranted or not.

 

[The_Whitetail_kid]

These are hot loads at and over book max. The Retumbo load is compressed. You didn't mention working up to these loads. Starting at max is pretty risky. I think if you had worked up these loads, you probably would have stopped earlier. I have seen soft brass cause sticky bolt lift at reduced charges before In my 28Nos complete with deep ejector marks, brass shaving sticky bolt lift, and super loose primer pockets. I pulled bullets and started over twice. My velocity data proved to me that an overcharge was impossible and a brass change was the fix.

going forward, even if you only shoot one round per charge weight over a chronograph in .2 or .3 grain steps (like the 10-shot satterlee), I think you should.

I did not start at max, started at 70 grains and worked up. 71.6 was where I found the best accuracy. As far as the accubonds, could not get it to group with lower powder charges. I do have a chrono but was just testing for accuracy yesterday.

 

[dogz]

run the loads over a clock then get back to us

 

[The_Whitetail_kid]

Couple of us have asked the speeds you're running, please check in and let us know the speeds of these loads. This day and age I can't imagine anyone not running a Chronograph when one can be had for $100 or so.

Keep in mind, no matter what you think your brass is telling you is that "pressure equals speed and speed equals pressure"...

So, please tell us the speeds of these loads

Did not chrono the accubonds, was just testing for accuracy . But that wasn't my first time with that load of 168's, and they get about 2984.

 

[ORTW1]

Hello everyone. Need some help here. I have shot 3 loads today at the range, and all three caused some sticky boat lift. I don't feel like the power charge is that high, and I'm not good at telling pressure signs by looking at the bottom of the case. In my 7RM. Thanks

Good Morning; Without being there I have only suggestions. Is the chamber clean, Have you checked the accuracy of your scales. Is the projectile touching the lands, did the bolt close easy or tight. Did you measure the head of the case before and after firing. I have learned not to trust the looks of the primer only because the manufactures standard on cup thickness if varying quite a bit. Not having the loading data in front of me I cannot comment on charge weight. The hard opening of the bolt is a sigh of pressure along with ejector marks but again it could be soft brass. My standard to working up a load is to measure the case head before and after at 90 degrees And not see any change in measurement. BTY I use a .0000 mike as well. Hope this helps and you find something to answer your investigation.

 

[The_Whitetail_kid]

Good Morning; Without being there I have only suggestions. Is the chamber clean, Have you checked the accuracy of your scales. Is the projectile touching the lands, did the bolt close easy or tight. Did you measure the head of the case before and after firing. I have learned not to trust the looks of the primer only because the manufactures standard on cup thickness if varying quite a bit. Not having the loading data in front of me I cannot comment on charge weight. The hard opening of the bolt is a sigh of pressure along with ejector marks but again it could be soft brass. My standard to working up a load is to measure the case head before and after at 90 degrees And not see any change in measurement. BTY I use a .0000 mike as well. Hope this helps and you find something to answer your investigation.

I can answer a few of those. My bolt with the accubonds is extremely hard to close. Not so much with the bergers. Yes, the chamber was clean. I did not measure the case head thickness this time. I will start in the future. Thanks.

 

[Barehandlineman11]

If its hard too close. Your either in the lands. Shoulder not bumped or case web is not being sized enough.

 

[The_Whitetail_kid]

If it's hard too close. You're either in the lands. Shoulder not bumped or case web is not being sized enough.

I'm currently in the process of switching over all my reloading die brands anyway. I know I am not in the lands. I was 20 thousands off on this particular load.

 

[Barehandlineman11]

When i size my brass i measure for reference. But i pull firing pin and size until bolt drops freely. In straight custom chamber .001 will do this some guns just a bit more. If your bumping past .0025 and still tight then your die isnt sizing base enough most likely. With ca reputation could be oversized chamber. Or your head spacing. New dies might fix it and might not. Id do some measuring first

 

[Wanashoot]

Appreciate the report on over pressure.

 

[Ozzy MN]

If its hard too close. Your either in the lands. Shoulder not bumped or case web is not being sized enough.

This is what I would check, i.e. shoulder bump/case web sizing. Especially since you said you have hard bolt closure.

 

[dogz]

Did not chrono the accubonds, was just testing for accuracy . But that wasn't my first time with that load of 168's, and they get about 2984.

Not to be redunant but ok so you've run a 168 over it, now do it with the bullet in question aka the 160 Accu and get back to us

 

[scpaul]

What does it do with box loads? Rem. Corelocks in green box (I guess it's still green, haven't bought any in years) had reputation for being mild velocity wise. Try some and look at those cases.