strenght of the 870 shotgun barrel

Shotgun Ammunition Reloading.
Post Reply
Posts: 20
Joined: Tue May 09, 2017 12:42 pm

strenght of the 870 shotgun barrel

Post by remmy870 » Fri Jul 21, 2017 11:40 am

any one having any info, storeys on the strength of our trusted 870 barrel?. would appreciate the info. the 870 barrel is SAAMI pressure stamped for 11500psi,i believe. in 2013 US. tom roster ballistic consultant done some test stating that they done pressure test on the 870 barrel starting with 20000 psi nothing happened. they went up to as high as 55000psi before finally the barrel blew up. that is well over the set margent of 11500 psi. this would all come into play if you are reloading shot US counter parts have all data and reloading equipment ,but not every one has that. some of us do reloading on a weight to weight ratio. I know what you are gone say stick to the loading data. but insome cases that is not possible as explained. so that's where this info comes at play. what is not to be confused is a barrel that blew up BECAUSE of an obstruction inside the barrel like stuck wad after a failed charge <like damp,wet shell>or mud etc. I looked deep into the question of blown up barrels and could not find anything on <reloading faults> blown up barrel most of them where related to obstructions bad shells etc. if you stick with weight to weight on a sensible scale like low cheap target loads like 28 grams. and the reload is just a bit lesser then the pay load, well packed recrimped etc . in theory this should be safe?. with reloading I mean: wax slugs .hot glue slugs.7/8 lee slugs.lyman 525 grain slug. and some buckshot sizes. any info would be nice thanks.

User avatar
Elite Shotgunner
Posts: 3022
Joined: Fri Dec 28, 2012 8:04 am
Location: The Inland Northwest

Re: strenght of the 870 shotgun barrel

Post by Synchronizor » Sun Jul 23, 2017 1:57 am

55,000 psi is the point where the barrel immediately exploded. Just because the barrel won't immediately burst at 40,000 PSI doesn't mean it's not stretching, deforming, or fatiguing from being pushed way over what it was designed for. You also have a choke, bolt, and locking block that have to contain that pressure. They're definitely not intended to contain rifle pressures multiplied by the cross-sectional area of a shotgun bore. Then there's the hull & wad that have to actually operate under pressure; are those bits of plastic really going to keep working the way they're supposed to under pressures that would be excessive in many rifles?

The 870 was designed to handle the pressure spec of the gauge & shell length it was chambered for. Just because one part was shown to not immediately, catastrophically fail when pushed past that limit doesn't mean that the gun itself is capable of handling overpressure ammo on a regular basis. It's a cool test that lets us appreciate how robust the 870's design is; it's not permission to be neglectful or reckless with your handloading.

From what I understand, the Lee Drive Key slugs meant for use in birdshot wads can be safely substituted in loads meant for the same weight of birdshot, though they generally require spacers to get a decent crimp. I've seen pressure trace data that supports this, otherwise I wouldn't be suggesting it or doing so myself. That may not be the case with other slugs, and I'm not sure about buckshot. There are outfits that offer professional testing for folks trying to assemble new shotgun loads. You fill out a form and send in the shells to be pressure-tested and chronographed using the proper test equipment. If you really want to experiment, this would be the responsible way to do it.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest