Aannnd now this evening
went and took those fired factory casings , annealed, resized trimmed tumbled all that, loaded them up with a cci small pistol primer and 10gr of lil gun n' a 40gr vmax aannnd
Man that's a sexy lil round

Now the very first one got hung up but the rest ejected and imo looks like I have very consistent fire forming
With my home made brass every one of them took a good bit of effort to get the case to eject even before firing, these little guys , take barely.1/4 of the same amount of effort

So another lil update, kept paying with the lil gun and H110 . Main problem now is I can't get more then three rounds without a round getting caught trying to eject. I mean factory stuff is working pretty close to flawless just ...it's not super accurate....talking about 1.5-2" @55yd . I mean I chose those caliber for 100yd and in and really 30yd and less but ... eghhhhh. Also the friggin recoil of this lil sucker with hotter loads is kinda ridiculous. Like I feel if it was a bigger / longer gun wouldn't be terrible but man it's actually kinda unpleasant to shoot. It's hort to explain but if you ever shot one of those cheaper bear barrel air guns and you feelm the weird snappy twangy type recoil they have ? Yeah well take that rack it up to about 10x . It's just violent as all get out.


Well anyhow I was about to self this lil guy for a bit buuuut I had two more pieces of prepped brass and about 70 somthing factory round to blow so went plinking a bit at 100yd. Fact stuff ain't to bad to shoot but as I said not too accurate was able to ding my 100yd prairie dog enough though. But I looks at this to prepped and primed pieces and just decided to try another powder for the hornet.... In this case 9.7 GR of IMR 4227. For som reason 80% of my good loads have been with some type of extended powder and this stuff is like a micro extended powder. Well loaded the two up wast exposing much at all aannnd a very nice soft recoil AND. Locked the bolt back each time !


No clue on how fast or well it shoots since is was just kind a shooting it just to see eif it would even work but I'm excited again . Also it's fire forming pretty decent, though it seems there's always one out of Every few that off

you might want to go back to the heavier spring and run a little lighter buffer

I think reciprocating mass is what you are likely feeling it feels like recoil but different

it is probably getting back far enough that the bolt and buffer is hitting the back of the buffer tube and transferring that shock into your shoulder of that weight slamming back against the buffer tube.

you want to get function without the slam at the back or the bounce at the front of the cycle

ideally high speed video of the firing cycle could help you tune your spring and buffer weight

Actually I went ahead and went back to the .308 buffer spring and the 4227 definitely shoots softer. But I ran out of 40gr Vmaxes and it's about time to get back to work so I'll play with it more next month. Gonna order a new spring though since I cut this one and I'm tempted to order some of the accurate TCM powder....since it's about the only thing theres actually load data for and it was specifically made for this cartridge.... Also I see mcgowen offers it for a custom barrel....buuuut 8-12 weeks


And I have alot of video I took just been to busy to sit down and edit

With the issues you're getting with the shoulder, is it moving towards the case mouth? With blow back 5.7x28 guns this happens as the action is opening up under pressure. I've heard the AR57 is notorious for this and I believe it. I just resized 250 pieces of range pick up brass and several had little to no neck and I've heard that's why. I didn't have any issue with resizing it but had to trim a bit.

Well the deal is only some seem to at random. Most fire for just fine then one out of every 5-10 will about wanna go in to a semi straight wall lol. And like I said no real rhyme or reason.

And the fun thing is , NO ONE really reloads or even shoots bottle neck cases in blow back rifles so don't really have anyone. To talk to or get advice about on this. One second I'm being told blow back is a complete different animal to other styles and then I'm having the same people then tell me how stuff is wrong....but using logic from normal actions gets a lil confusing lol.

That being said I've just said screw it and I'm treating it like a over sized pistol

That's definitely strange it's not all of them but that sounds a bit like the AR57 too. Sounds like once the chamber heatedbup the temp would cause a pressure change to start cycling the action under too much pressure. I've never loaded for a blowback outside of a 9mm pistol so not something I am that knowledgeable about. That being said I'm glad my 5.7 is the S&w M&P5.7 and the gas assisted action seems to help with shoulder movement some. Good luck with this project, I've always thought the time was a cool round.

Ok I have a theory that would need a little testing

first thing plunk test a bunch or rounds , this is pull the upper, pull the bolt , barrel vertical , muzzle down you start the loaded round on the feed ramp about half way to the chamber and let it slide it goes all the way in with a plunk or it doesn't mark all the ones that don't with a sharpie , now measure the neck of the round and then measure some of the ones that plunk very nice maybe a factory round

my theory is you get some rounds too thick in the neck , they don't get all the way chambered but being a blow back and very capable of firing out of battery , that you get about half the neck into the neck of the chamber

my dad and I have the same upper from Brownells about a year apart maybe only 9 months , his chamber is tighter than mine I can chamber rounds he can not , his bolt will not close on them fully.

he will have rounds not go into battery , now being a traditional AR bolt if it isn't in battery it doesn't lock up , it won't fire

I only had the issue with cut down and re formed 223 cases , mostly had it with a couple brands , measuring the neck will tell me if his gun will take it or not

I think this might be what is happening , but the blow back can and will fire out of battery , your just almost in battery so you just get almost strait cases