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Message
re: + P Ammo Question
Posted on 12/27/24 at 12:20 pm to Bayou Ken
Posted on 12/27/24 at 12:20 pm to Bayou Ken
quote:
From what I can gather, most modern rifles can handled pressures between 60,000 and 65,000 PSI depending on the cartridge. For my gun, the + P ammo pressure hits 58,000 psi compared to 54,000 psi for the non + P rounds. I haven't made a decision on which way I'm going to go but I wanted to share what I found out. I might have to start reloading if I can't get regular factory loads.
So the 257 is long action, I would look at what pressure some other long action cartridges are creating tbat the a bolt is chambered in and fire with confidence if less tban tbat.
It’s the same action and barrel profile and if anything the 257 will be a thicker wall thickened than say a 270 or any larger dia chamber.
1
Posted on 12/27/24 at 1:03 pm to Bayou Ken
I have a slightly older (thank yours) 257 Bob A-bolt and I've been shooting the Hornady Superformace 117 grain +P ammo. I haven't noticed anything negative. I don't go through much ammo with the .257 since it has been so scarce lately so I'm not sure about long-term effects.
Posted on 12/27/24 at 1:06 pm to Ol boy
Right. A 270win in the same action is rated to 65,000 psi with less metal. Not advice, just facts.
Posted on 12/27/24 at 1:21 pm to Bayou Ken
I personally wouldn't use +P. You might get away with it for say two boxes of ammo, but might have busted barrel on 3rd box. A castrophic failure due to higher pressure weakening while using first couple boxes of +P ammo.
This post was edited on 12/27/24 at 2:49 pm
Posted on 12/27/24 at 6:26 pm to Bayou Ken
Traditional proofing they would use 135%-145% of the pressure of the cartridge. This is going to vary wildly by manufacture and country of manufacture. Some old proof testing was done at 400% of the targeted rating... that's just ludicrous... and some black powder guys still do this for some weird reason and they don't actually proof the barrel, they don't take pre or post measurements so they don't know if the barrel was "proofed" at that charge anyway.
Proofing is to determine if the barrel will change it's static shape with a given pressure/charge, not to determine if a rifle is safe to shoot. Some people don't understand that and that is how you get black powder guys shooting 400% charges and thinking they proved anything. Having a firearms background AND science background can be very frustrating at times.
Proofing is to determine if the barrel will change it's static shape with a given pressure/charge, not to determine if a rifle is safe to shoot. Some people don't understand that and that is how you get black powder guys shooting 400% charges and thinking they proved anything. Having a firearms background AND science background can be very frustrating at times.
Posted on 12/27/24 at 10:37 pm to armsdealer
quote:
some black powder guys still do this for some weird reason
Guessing that reason is accidental charge of smokeless powder instead of black powder.
Posted on 12/28/24 at 3:05 pm to Drive4show
Great whitetail round by the way. Big fan
Posted on 12/28/24 at 4:16 pm to TheDrunkenTigah
quote:
accidental charge of smokeless powder instead of black powder.
Seems like 100+ grains of smokeless in a muzzle loader would be like 4000% pressure not 400.
Posted on 12/30/24 at 2:31 pm to Bayou Ken
quote:
So, the tech at Browning couldn't tell me that I can shoot the + P ammo in my .257 Roberts but he didn't say I couldn't. When I asked him what the PSI allowance for an A-Bolt is, His answer was that that was proprietary company information and he couldn't disclose that psi information.
Sounds like you got a customer service rep working from home who didn't have access to the technical info and/or didn't really want to try very hard to help you. I'd imagine your A-Bolt is chambered in a number of other rifle rounds (e.g. 243, 6mm Remington, 6.5 CM, 7-08, 308, 30-06, ad nauseum) that run at likewise, if not slightly higher PSI than the +P 257 Roberts ammo in question. The 6mm Remington in particular is interesting since it's basically the 7x57 Mauser necked down to 6mm whereas the 257 Roberts is the 7x57 necked down to 0.257. Historically, the 257 Roberts has been loaded to lower pressures than similar rounds out of respect to a lot of older 257 Roberts built using actions not safe for the higher pressures of modern rounds. +P indicates its loaded to the same pressure level as other modern rounds.
ETA: I've never seen a rifle barrel labeled +P, regardless of the round.
This post was edited on 12/30/24 at 2:34 pm
Posted on 12/30/24 at 3:11 pm to Bayou Ken
Years back I had a Browning Lever Action in 257 Roberts that I put a great many rounds of Federal with Nosler Partition bullet +P thru with never an issue.
Posted on 12/30/24 at 3:51 pm to TigerOnThe Hill
quote:
Sounds like you got a customer service rep working from home who didn't have access to the technical info and/or didn't really want to try very hard to help you.
More like there is no way in lawyer filled hell Browning is going to tell you anything above SAAMI max is safe. Even if he finds a scanned document from 40 years ago saying it can handle it, he’s not gonna be able to say that.
Posted on 12/30/24 at 6:50 pm to TheDrunkenTigah
quote:
More like there is no way in lawyer filled hell Browning is going to tell you anything above SAAMI max is safe. Even if he finds a scanned document from 40 years ago saying it can handle it, he’s not gonna be able to say that.
That's true. But CS could've just as easily made a factual statement like, ".257 Roberts +P" has a SAAMI maximum pressure limit of 58,000 psi compared to the 54,000 psi for the standard .257 Roberts."
I'm becoming increasingly more frustrated dealing w/ CS of nearly every industry. I recently finished an exchange of 4 emails from me to Brownell's about an old Sinclair product. Bottom line, although the product is in their currently online catalog, the product and the $10 accessories I need are no longer available. Of course, the $120 Redding product is.
ETA: Apparently the 257 Roberts is the only rifle cartridge w/ an official +P designation.
This post was edited on 12/30/24 at 6:53 pm
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