A friend and I were trying to get his suppressed M1A to shoot subsonic. The risk of a very light load, after some research, is that the small amount of powder may get ignited at the boolit end and not the primer end. With the powder burning backwards, pressure builds up towards the back end first and it’s like a shape charge and the pressure is not released by the boolit being released. That’s the theory and why people use fillers to keep all the powder back at the primer.
My friend didn’t think we needed filler, so we didn’t use any. It was his gun. We used a flake pistol powder. Never had a bad experience except the boolits would keyhole before we got subsonic. Maybe a faster twist could of helped. We were always chambering individual rounds and I made sure all the powder was tapped down so it would all be next to the primer.
I have been running H110 in sub guns, ARs and TCs since JD Jones developed and introduced the Whisper. Never had a problem with sub loads using H-110 or 296 following JD’s directions. I run my 220g PCed cast with SRPs subsonic with JD’s published H-110 loads also run 160s in the 6.5 Grendel with H-110. Never had a problem in 40 years.
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Mal
Mal Paso means Bad Pass, just so you know.
It's been called a keyhole for billions of years. Get used to it.
Let's go Brandon!
I couldn't get H110 to work in my 300 BO pistol worth a darn. I'd say get powder made for that round.. I've seen CFE BO several times with very little else on the shelves. It works well. I have a bunch of H110, using it in 22tcm.
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Hogdon offers load data for .300 BO subs using H-110. Most of them call for a magnum primer.
I'm using WW296 (aka H110) to push a Maker 85 to 2300 fps out of a 10" barrel. It works fine. But I wouldn't use it for subsonic loads. It would be totally unsuited for that unless it was (maybe) in a manually operated action. Even then it wouldn't be my first choice.
Let's go Brandon!
My experience wasn't really with "underpowered" loads.... But that was what I was moving towards. I have a few sub cartridge adapters, 2 for 7.62x54r and two for. 303 British, one of each for 7.62x25 and 32 ACP. I was shooting some 32 ACP from the. 303 adapter, going as quickly as possible, because I planned to reload them with heavy for cartridge boolits for cat sneeze shooting, when I heard a strange report..... Following due diligence, I stopped, cleared the gun, and realized I'd experienced a squib. With more examination, I found the barrel had split at the band for the front sight, and upon removal of about 3" of barrel, I found there to be 5 bullets in the barrel. This particular rifle has considerable" windage" in the barrel, measuring about .317, and the small bullets of the 32, plus the blow by, plus my hurriedness, created a perfect Storm of errors. Thankfully, this particular SMLE was already severely bubba's when I got it, so it just continued to be a project rifle!
H110 works well for me in subsonic and supersonic BLK loads. There’s plenty of load data for it and it’s one of the more common powders used. I’m sure millions of rounds have been sent down range with it.
What charge weight were you using, what happened while shooting and why do you think the bolt is ruined?
I come down in the camp of using VERY fast burning and easy igniting powders for underpowered loads.
I ALWAYS use a flashlight to verify no double charges. I also never use case fillers.
The older Lyman books such as #45 and pre, are your friend for published data for these loads, and the common and proven powders are usually the standard pistol powders. I don't see H110/W296 list among them. That powder has always had a rep for unreliable ignition and incomplete burn at low pressure. I do often see 4227 listed for light loads. jd
It seems that people who do almost nothing, often complain loudly when it's time to do it.
What you had or were close to having was an SEE (Secondary Explosive Effect). Some refer to it as a "Pressure Excursion".
Smokeless powders do not "detonate" in cartridges, they burn. How and when they burn is the problem.
The cause of SEE is well understood since the advent of piezo-transducer and strain gauge pressure measuring since the '80s. There is an excellent explanation that was published in a Handloader article which I have posted here numerous times. An SEE can easily be reproduced pretty much "on demand". Being able to measure the pressure, observe the Rise to peak pressure and the time pressure curve/trace has allowed me and others to observe the potential SEE before it occurs.
All of the old theories (which are/were not reproduceable) may have sounded good but they were not the actual cause of an SEE.
What actually occurs is a series of conditions (not all the conditions need be present) lead up to the root cause of an SEE....a bore obstruction. Seldon does an SEE occur with just one or two shots. It usually will occur with shots three through 10 +/-. In the case of your AR with that reduced load of H110 the force of the primer pushed the bullet into the probably already fouled throat/leade/bore where it stuck because the powder had not yet begun to burn. Then the powder began to burn and it reached excessive pressure before the bullet began moving fast enough to lower the pressure from the expansion ratio as the bullet moved down the bore. SEE's do occur with cast bullets but usually the bullets begin moving because cast are softer than jacketed. Fortunately for you, the cast bullet began moving before the pressure really got high.
All this occurs very quickly, in milliseconds, and is usually not noticed. However, sometimes a "click/bang" effect is noticed. That is an omen of potential SEE and any time a click/bang occurs you should stop using that load.
Over the last 50+ years I have been directly involved with a couple SEE's that actually did destroy the firearm. I also have been involved in several probable SEE's and have investigated others that were found to be probable SEEs. I also have on several occasions while pressure testing loads observed the buildup of pressure that leads to SEEs. I stopped testing before the SEE occurred.
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
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