Inconsistent recoil, flash, and ejection

Reloading info for the 5.7x28mm

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spyderco monkey
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Inconsistent recoil, flash, and ejection

Post by spyderco monkey » 18 Mar 2016, 22:21

I just started loading 5.7x28 for my Five-seveN. I fired 59 rounds at the range today through my brand new gun, and saw the slide short stroke a number of times. In addition, the flash, recoil, and noise from the fired rounds was very inconsistent. One round would produce a huge fireball, and the next would produce a more subdued "pop". Ejection distances varied from going 15 feet downrange to landing right in front of me. Several rounds barely cycled the slide, and left the spent brass in the chamber. These shots had noticeably less recoil than most others.

I used the following load:

Wolf Small Rifle Primer
Sinterfire 42gr bullet
5.8gr True Blue (weighed every charge)
1.130" Trim Length
1.585" OAL

The first 39 rounds were not crimped. The last 20 all received a light crimp with a Lee FCD. The failures were roughly evenly distributed with both crimped and uncrimped rounds.

The brass I used was all in good condition. I initially cleaned them with Simple Green, and followed up with a 1.5hr tumble in untreated corn cob media to remove the case lube after sizing. I am certain that the coating was fully intact.

The rounds all fired and did not exhibit any pressure signs. The groups weren't too bad either. I chrono'd them with a MagnetoSpeed chronograph with the following results:

Series Shot Speed
3 1 1784 ft/s
---- ---- ---- ----
Series 4 Shots: 8
Min 1752 Max 1843
Avg 1809 S-D 34.5
ES 91

Series Shot Speed
4 1 1782 ft/s
4 2 1803 ft/s
4 3 1841 ft/s
4 4 1843 ft/s
4 5 1826 ft/s
4 6 1843 ft/s
4 7 1752 ft/s
4 8 1782 ft/s


Series 5 Shots: 10
Min 1780 Max 1857
Avg 1816 S-D 21.8
ES 77

Series Shot Speed
5 1 1780 ft/s
5 2 1793 ft/s
5 3 1826 ft/s
5 4 1813 ft/s
5 5 1799 ft/s
5 6 1857 ft/s
5 7 1834 ft/s
5 8 1821 ft/s
5 9 1815 ft/s
5 10 1823 ft/s

Series 6 Shots: 9
Min 1798 Max 1862
Avg 1826 S-D 18.1
ES 64

Series Shot Speed
6 1 1862 ft/s
6 2 1829 ft/s
6 3 1823 ft/s
6 4 1841 ft/s
6 5 1813 ft/s
6 6 1818 ft/s
6 7 1798 ft/s
6 8 1819 ft/s
6 9 1833 ft/s


So there were a couple of shots that registered unusually low velocities. However, this does not seem to reflect to extreme level of inconsistency that I felt when firing the gun, as well as the multiple failures to extract. I'm guessing that some rounds experienced incomplete powder burn, but I can't figure out why that would happen.

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grimmond
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Re: Inconsistent recoil, flash, and ejection

Post by grimmond » 19 Mar 2016, 20:22

What are you using to weight your charges? I had a similar issue with an electric scale that was having electromagnetic interferences and the weights were inconsistent until I isolated it and used an anti static spray on the parts.
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Kiran04
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Re: Inconsistent recoil, flash, and ejection

Post by Kiran04 » 19 Mar 2016, 22:10

I only have issue with the LFC on my rounds, but it does cause the behavior you describe. No idea the cause.

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grimmond
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Re: Inconsistent recoil, flash, and ejection

Post by grimmond » 20 Mar 2016, 10:10

One other thing that can cause the inconsistencies is the amount of crimp. If every case is not crimped with equal pressure and location on the neck and such can also cause that. Thats why crimping can be such a pita to get set right.
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Grantness
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Re: Inconsistent recoil, flash, and ejection

Post by Grantness » 20 Mar 2016, 13:14

Could have something to do with the sinterfire bullets.
I seem to recall needing to use caution crimping them (i avoid it).
Also, the shooters grip can affect cycling.

I've never bothered tumbling 5.7 cases. Simple green and dish soap followed by a water rinse works great and u don't have to worry about damaging the coating or accidentally capturing some media.

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LK45s
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Re: Inconsistent recoil, flash, and ejection

Post by LK45s » 21 Mar 2016, 19:47

What Grant said about the crimping. Sinterfire recommended no crimping. It could crack the brittle bullet. I glued mine and had no problems. Although it was a bit tedious gluing. Clear nail polish (nitrocellulose) was used to glue.
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DoubleJ
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Re: Inconsistent recoil, flash, and ejection

Post by DoubleJ » 24 Mar 2016, 16:47

Tell us more about where you reload. Cold garage to warm house for any of the components? I've not used sinterfires with BD, but they work fine with AA7. Could be a powder or primer contamination issue.

Kiran04
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Re: Inconsistent recoil, flash, and ejection

Post by Kiran04 » 24 Mar 2016, 20:03

LK45s wrote:What Grant said about the crimping. Sinterfire recommended no crimping. It could crack the brittle bullet. I glued mine and had no problems. Although it was a bit tedious gluing. Clear nail polish (nitrocellulose) was used to glue.
How did you glue it? Just apply it to the bullet before pressing it in? Did it take a long time and complicate the process? Worth? Yes/no? How long do you have to adjust bullet depth before the glue dries?

jeffa
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Re: Inconsistent recoil, flash, and ejection

Post by jeffa » 30 Mar 2016, 04:44

Interesting on the eject issues.

Thats the only thing I noticed before my gun blew apart while shooting some reloads of unknown origin.

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K-C
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Re: Inconsistent recoil, flash, and ejection

Post by K-C » 09 Jun 2016, 14:06

jeffa wrote:Interesting on the eject issues.

Thats the only thing I noticed before my gun blew apart while shooting some reloads of unknown origin.
WOW! I hope you're okay, presume you are as there's no blood or "body parts" in any of the photos...

Great pity about the FsN a valuable lesson learned the hard way. I'd have a meltdown if that happened to mine.

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Re: Inconsistent recoil, flash, and ejection

Post by Buffman » 09 Jun 2016, 20:15

jeffa wrote:Interesting on the eject issues.

Thats the only thing I noticed before my gun blew apart while shooting some reloads of unknown origin.

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Where did you get the reloads from?

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Re: Inconsistent recoil, flash, and ejection

Post by panzermk2 » 10 Jun 2016, 12:12

Damn how did I miss this thread????????
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spyderco monkey
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Re: Inconsistent recoil, flash, and ejection

Post by spyderco monkey » 12 Jun 2016, 22:09

It would be great to have those rounds torn down and analyzed.

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Re: Inconsistent recoil, flash, and ejection

Post by NLVMike » 13 Jun 2016, 05:47

Spiderco, that makes no sense to me that the chrono results are relatively consistent, with inconsistent recoil. My amateur opinion is that you are pushing a 52 grain bullet pretty hard. I get roughly the same velocity with my reloads of 40 grain vmax bullets out of my pistol. That is a brittle bullet, and that weight is usually relegated to subsonic loads for the pistol. Jetta's comment was subtle, but I heard it loud and clear. I don't want his experience, even once.

You said there were no signs of overpressure, but to me, inconsistent recoil and ejection are signs that I watch for, along with flattened primers. I would back that load down. Just my $.02.

Mike

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Re: Inconsistent recoil, flash, and ejection

Post by bruteandbear1 » 13 Jun 2016, 14:09

Maybe your scale is improperly calibrated? I don't have any experience in media so I'm not sure what would happen if some media got stuck in the casing, loaded with powder, seated bullet and ultimately shot it with media in the casing? Any thoughts :ponder:.

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panzermk2
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Re: Inconsistent recoil, flash, and ejection

Post by panzermk2 » 14 Jun 2016, 07:16

The feel of the recoil will change if the case or the primer give out. You can get to a point where your FPS stabilize and not really change much for about .4gr of an increase. This is due to the case stretching out. Something to think about.
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Re: Inconsistent recoil, flash, and ejection

Post by Oldbindlestiff » 14 Jun 2016, 09:58

NLVMike wrote: You said there were no signs of overpressure, but to me, inconsistent recoil and ejection are signs that I watch for, along with flattened primers. I would back that load down. Just my $.02. Mike
:agree:

A safe, accurate and consistent loading is much more important than velocity. Good luck.

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Re: Inconsistent recoil, flash, and ejection

Post by panzermk2 » 14 Jun 2016, 13:33

FYI this load is above max pressure.
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GONRA
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Re: Inconsistent recoil, flash, and ejection

Post by GONRA » 15 Jun 2016, 13:32

GONRA has trouble sorting out exatly WHAT his load was.
Can some one repeat it? THANX!

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Re: Inconsistent recoil, flash, and ejection

Post by Rapier1772 » 15 Jun 2016, 15:12

From the OP:
used the following load:

Wolf Small Rifle Primer
Sinterfire 42gr bullet
5.8gr True Blue (weighed every charge)
1.130" Trim Length
1.585" OAL

The first 39 rounds were not crimped. The last 20 all received a light crimp with a Lee FCD. The failures were roughly evenly distributed with both crimped and uncrimped rounds.
I haven't done 42gr bullets but on my 45gr bullets, 5.5gr of TB was max. There's a point where more powder works against you with speed & consistency, I think you hit it. Recommend that you drop your charge a bit & retest
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