custom vs stock rifle limits?

[alaskabushmaster]

Some questions about rifles and pressures. I have been looking at the Trident +p loads and some of our hot handloads. I have a 20in stock bushy in comparison to the custom rifles what can our off the shelf rifle handle? I feel I could duplicate the speed but maybe at the expense to my face. I have touched 2400 with XTPs. I obviously don't have a way to measure exact pressures of this load but looking at all the pressure signs it was safe. Does anybody know the working pressures of the loads above 2500-2700?

[gunnut]

I've been using 230grn.FMJ @ 45grns of LiL Gun for over a year now. With, No Ill Effects."Recoil testing load".
Primers started to flatten "but not flat" @43. but, when away and did not return until 47. I backed off to 45.
I was told I was running around 50-55KPSI. with the upper limit being 60KPSI Max. I know the factory rating is a very conservative 40KPSI.
I do not encourage others to do this.. I just need recoil.

[Hoot]

My experience suggests that the cases need a certain amount of pressure to hang onto the shiny chrome plated chamber walls. That's not a one or zero condition. They hang on tighter as the pressure goes up. At some point in excess, they can't hang on tight enough for the amount of push back and it's not unusual to see them start imprinting with the ejector and extractor. Also, around the primer where the head presses into the firing pin hole, AKA cratering. Then, beyond some threshold of pressure increase they over come even the slipperiness of the chamber and start holding on tighter as they expand more under pressure and head indicators drop off somewhat, or don't get worse. It doesn't mean the pressure went down. It just means you can't rely as much upon the head for indications of excessive pressure. At that point, it's not unusual to observe case enlargement just above the web. That now becomes your primary signature of pressure. Beyond that, you're on your own as I've never been there, but I expect that if you have reloaded cases where the primer pockets are starting to get looser, you see gas signs around the primer. I myself do not look to the primer as much of an indicator as it can some times be misleading. Obviously, if they're flattened, you up into cautious territory, but you may be there without them totally flattening. Small primers hold onto their pockets amazingly well compared to large primers. If you're loading .284 cut-downs, you will see more primer distress as an indicator.

There's another factor and it relates to how fast they rise up to full pressure. Faster powders versus slower ones; Neck tension; Bullet weight; Even primers factor into how well they seal into the chamber and hang on. It's certainly not a simple expression with only one or two variables. That's where you really need a pressure barrel as closely constructed in material, manufacturing method and tolerance to your real-time barrel, so that the pressure barrel's readings relate to you experience with your non-testing barrel.

Hoot

[bushmeister]

At that point, it's not unusual to observe case enlargement just above the web.

Hoot, that's some great info! I almost understood all of it. Please explain what you referred to as "the web"

[Hoot]

At that point, it's not unusual to observe case enlargement just above the web.

Hoot, that's some great info! I almost understood all of it. Please explain what you referred to as "the web"

Usually, cartridge terminology is covered in your Reloading Manual, but here's the one picture worth a thousand words.



If you take one of your fired 450b cases, wipe off the soot and look at it with light reflecting off of it, you will see a clear step where the outside diameter increases just above the web. The hotter the load, the more distinct the step will appear. It can be measured accurately with a micrometer. Also, the chamber wall tends to impart a change in luster where the case presses against it during combustion, which aids in seeing the step.

Hoot

[wildcatter]

At that point, it's not unusual to observe case enlargement just above the web.

Hoot, that's some great info! I almost understood all of it. Please explain what you referred to as "the web"

Usually, cartridge terminology is covered in your Reloading Manual, but here's the one picture worth a thousand words.



If you take one of your fired 450b cases, wipe off the soot and look at it with light reflecting off of it, you will see a clear step where the outside diameter increases just above the web. The hotter the load, the more distinct the step will appear. It can be measured accurately with a micrometer. Also, the chamber wall tends to impart a change in luster where the case presses against it during combustion, which aids in seeing the step.

Hoot

_______________________________________________________________
_________________________________
_____________

The line, as Hoot is trying to explane, can clearly be seen in this picture. This is where you measure, for case head expansion. Also I use a dental pick to reach into the case to feel for the valley, just north of the web and at the line, on the inside of the case. That valley tells me to discard the case, because that's the sign of impending case head separation. You won't feel this valley for many reloadings, and I have reloaded as many as twenty times before I finally do feel it, but you could feel the valley in as few as three reloadings. But, when you do finally feel this valley, discard that case.

Case Head Expansion: You'll have to measure the Before/After cases. Now, when we know what to measure, how much expansion is too much? Of course if you allow too much expansion, case life goes dramatically down or you're going to separate the case head, from the body.

Generally speaking, our very tame, factory ammo won't expand at all. Myself, I allow .0015" expansion and I know guys that do 2 thou plus, but for any new reloader or new to this method, better stick to, allot less than .001" expansion.

Remember, you have to measure this line, right after you full length resize the 450b case and then again after firing it. Do I need to say it has to be the same exact case, for the before/after measuring?

Keep in mind, that case head expansion is but one tool, and not to be relied on, by itself, different lots WILL expand differently. Some, even think that case head expansion is a poor method, at best, for measuring pressures. But, feeling for that inner valley is a must. That valley is distinct and you won't normally miss it, if you take your time, and use a proper tool, even a bent paper clip will work..

..t

[bushmeister]

Usually, cartridge terminology is covered in your Reloading Manual, but here's the one picture worth a thousand words.
Hoot

Yeah, but I don't bring my reloading manual to the office...Of course I don't look at forums here either

Thanks for the explanation. I did buy a reloading manual with my dies, but so far I've only loaded up to factory loads until I get more comfortable with it. Alaska, sorry for the highjack. Hoot, Catter, thanks for the great explanations.

[alaskabushmaster]

There was no thread highjack it's OK. It all ties into what I was asking. I got answers to case life and pressure signs without directly askings. My questions will usually inspire others to ask their own. Its all in the process of learning. I grew up with a gunsmith as a grandfather and I love to see others ask their own questions. This thread gives people an idea of what their stock rifles will handle and some signs to look for when you are getting a little risky. I'm sure this has been asked in another thread somewhere before but its always nice to have a fresh look.