Subsonic loads go unstable only with can

Reloading info for the 5.7x28mm

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mxgobig
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Subsonic loads go unstable only with can

Post by mxgobig » 13 May 2014, 06:22

Just like the title says, my subsonic loads look great...
They cycle the slide. Are stable at 15 yards. Are subsonic.
Until I screw on the suppressor... Then the keyholes start.
Has anyone seen anything like this

Here are the details:
Fiveseven pistol
1:8 twist barrel (yes I know 1:9 is standard)
Multiple bullets and manufacturers from 55gr to 69gr
Multiple powders
SWA spectre II suppressor (no baffle strikes)
Velocities are all around 950 to 1050
Barrel is true and functions fine
Threads are straight and true also
Everything is tight.

I know the bullets I'm trying are heavy, but I don't understand why the appear to stabilize without the suppressor.

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panzermk2
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Re: Subsonic loads go unstable only with can

Post by panzermk2 » 13 May 2014, 09:04

Above 55 you are really sticking your own neck in a noose.

How do you know for a fact you are not having baffle strikes?
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mxgobig
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Re: Subsonic loads go unstable only with can

Post by mxgobig » 13 May 2014, 09:40

I disassembled the suppressor and inspected the baffles...
No marks or dings at all.

I understand that even with the faster twist barrel that these may not work.
I am just trying to understand why I don't get any signs of instability with the no suppressor.
Last edited by mxgobig on 13 May 2014, 15:54, edited 1 time in total.

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panzermk2
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Re: Subsonic loads go unstable only with can

Post by panzermk2 » 13 May 2014, 10:13

I still think you getting a strike. Sometimes it is very hard to tell.
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mxgobig
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Re: Subsonic loads go unstable only with can

Post by mxgobig » 13 May 2014, 10:51

First, panzer thank you for your input.
I appreciate the help.

I found this on another forum... and I am running an adapter on the spectre that might be putting the muzzle closer to the first baffle. I will have to measure tonight to check.
What do you think of this?

"Keep in mind that some .22 rifles have 1/2x28 threads that are too long (like the M&P-15 .22) and the suppressor either doesn't properly shoulder or it shoulders but the the crown is too close to the first baffle. If the suppressor doesn't shoulder properly it will be misaligned and you can get baffle strikes. And if the suppressor shoulders but the bullet exists the barrel too close to the first baffle, it can cause the bullet to be unstable and you could get baffle strikes. (I saw this happen with a Spectre II on a M&P 15 .22; the baffles on a Spectre 2 are asymmetrical, and the fact that the bullet exited too close to them cause it to keyhole in the target. Luckily there were no baffle strikes.) But this is all easy to fix with a $10 spacer like the one from Gemtech."

Again, thanks for the help.

DoubleJ
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Re: Subsonic loads go unstable only with can

Post by DoubleJ » 13 May 2014, 16:01

I'd think any spacer would help for the time being, even a crush washer or something, to see if that's your issue. Keep us informed, I've just started playing silencers myself and I'm in the market for either a Sparrow or an Axiom.

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Re: Subsonic loads go unstable only with can

Post by bruteandbear1 » 14 May 2014, 04:38

Just like jay said anything under 55 grains is really unstable. I Would Use Some 50 Grain FMJ's If You Can Find any. If Not Stick To 55 Grain Max And Dont Go Over Because You Will Have Performance Issues, best Of Luck Let Us Know What U Find Out.

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Re: Subsonic loads go unstable only with can

Post by Buffman » 14 May 2014, 08:31

you should only use shims if you want to move it out. Crush washer may make the suppressor and or adapter non concentric to the barrel.

shopsmart
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Re: Subsonic loads go unstable only with can

Post by shopsmart » 17 May 2014, 04:42

I have first hand experience with this kind of problem. If you look on the other forum my PS-90 sbr / silencer story is somewhere over there. The posted above 1/2x28 info is true. Our 22 cans are .4 depth of threading while alot of mounts are .6 depth. There are .2 spacers out there. Just do a google search and you can find a 3 pack for $20. Yes it is close to the first baffle, but it is the blast chamber that is part of the problem. Gases might be throwing off the stablity.

The other part is baffle strike. Mount the supressor, look through. If you see any baffles, congrats, you have someone to yell at. The other is look VERY carefully for any slight crescent moon. You can do this by moving left right up down the barrel in your eye sight. See any imperfections? Congrats you have someone to yell at.

Hope that helps.

Oh yeah, 62 grain pills are possible, but noose yes. However FN looks to have transitioned their subs to 62 grains. Some people are investigating, but months and months out as far as research or actual subs in hand I imagine.

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Re: Subsonic loads go unstable only with can

Post by panzermk2 » 17 May 2014, 11:39

The 62gr was a prop round and fake. It was made for a show.

62gr will never stabilize out of the FsN.
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mxgobig
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Re: Subsonic loads go unstable only with can

Post by mxgobig » 20 May 2014, 17:48

Looks like it was the muzzle too close to the first baffle.
Things started to come out of the can a lot better after I corrected the spacing.
60 grain v-max may still be on the heavy (long) side... I think I'll take Jays advice and try 55s...
Thanks for the help!!!

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Re: Subsonic loads go unstable only with can

Post by panzermk2 » 20 May 2014, 21:12

Glad we got things sorted.
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GONRA
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Re: Subsonic loads go unstable only with can

Post by GONRA » 15 Aug 2018, 07:27

“Good ‘n Bad News” Info that may (or may not) be interesting to some of ya’ll:

GONRA’s FN FiveSeven pistol, EA threaded barrel / recoil spring assembly,
Gemtech suppressor, handloads using FN and EA brass, etc.
>>> CCI #500 SMALL PISTOL primers, 55 gn. FMJBT bullets. <<<

Modest 3.0 grain Bullseye powder charge loads with fresh “used as is, NO ADDTIONAL CASE LUBE”
5.7x28 07 EA brass CASES functioned OK but had several fired cases with BODY SPLITS.
(Never saw any BODY SPLITS in quite a bit of resized FN Scharch brass reloading. ???)
Bad News: Bullet went unstable in suppressor.

Assume it’s a message to NOT use Bullseye in this caliber? ???
Cases were bulged, primers eyeballed Just Fine….

3.8 grain HS-6 powder load in resized FN Scharch brass functioned Just Fine
Bad News: Bullet went unstable (keyholing) thru suppressor.
5.0 grain HS-6 powder load in resized FN Scharch brass functioned Just Fine
Good News: Bullet traversed suppressor (NO keyholing) Just Fine.
>>> POSITIVE illustration of “spin it up to (hopefully) get stability, survive suppressor”. <<<

4.5 grain HS-6 powder load in fresh 5.7x28 07 EA brass
(thiiiin coat STP Oil Treatment rubbed onto case body to mimic my resized FN Scharch brass ,
reduced powder charge for smaller EA case capacity) functioned Just Fine.
Good News: bullet traversed suppressor (NO keyholing) Just Fine.

Yup, its NOT a “subsonic load” but will load some of this ammo for Generalized Blasting…….
(As you can imagine, havalotta BAD NEWS loads that are NOT included here.)

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Next step is to seek a subsonic load with 50 grain Hornady SP bullets per panzermk2 suggestion.
Load up 4.5 grain HS-6 powder charge in fresh 5.7x28 07 EA brass
(thiiiin coat STP Oil Treatment rubbed onto case body) .
Assuming bullets traverse suppressor OK will then load powder charge DOWN in 0.1 grain increments, until bullets “go unstable” thru suppressor.
With that data, hope to verk up a POSSIBLE subsonic load for my pistol.

By starting at the top and verkin’ down,
won’t drive myself nuts seeking something that’s never gonna happen.

GONRA
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Re: Subsonic loads go unstable only with can

Post by GONRA » 25 Aug 2018, 13:17

GONRA’s FsN pistol. Gemtech suppressor, EA barrel heavier recoil spirng 9 yard shootin’ experiments with 10 rds.
EA brass, 50 grain Hornady SP SX #2240 bullets, CCI #500 pistol primers.
Started off with 4.5 grains HS-6 powder.
Everything still functioning just fine. Still have “no keyholing”.

Now down to 3.8 grains HS-6.
(Adjacent shooter thought I was shootin’ squibs, so Gemtech is functioning great!)

Use “olde fashioned” one hand bullseye stance.
Had 8 shots in nice 1+ inch group, 2 (apparent) flyers 3 inches from center of group.
(At my age must assume these “flyers” are just ME screwing up – NOT REALLY “flyers” -
but have no way of knowing for sure.)

BUT – just for the hellava it, have any of you “super really careful shooters”
ever noticed such a “onset of instability” when carefully investigating these issues?
(We all know keyholing WILL begin as powder charge is further reduced.)

Pleeze lemmeno. THANX!

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