Lil Gun Hot Weather Chrono, just checking

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AccelR8
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Lil Gun Hot Weather Chrono, just checking

Post by AccelR8 » Thu Jun 23, 2022 9:15 am

150 grain Hornady fmjbt. CCI small rifle primer. WW Super 222 Rem converted case. 15.5 grains Lil Gun. COAL 2.066 inch.

98 degrees F, full sun (if that matters) 78% relative humidity.

Shot ten rounds while sighting in both irons and a scope so shooting was not fast at all, at least two or three minutes between shots with a very long unexpected break in the middle to help a new shooter. In other words barrel/chamber heating was not an issue.

If I throw out 3 chronograph readings which are WAY out of the expected range, for the remaining seven shots I have an average of 1904 fps, 115 ES and 42 SD.

But, I have one shot that read 2794 fps, another that read 2460 and one that read 1289.

Magnetospeed Sporter chrono. It has always worked reliably and provided believable data. In fact this day I also used it on another rifle and data was consistent and believable.

Here's my question; am I right to discard those three readings as errors? I really don't think that 2794 fps would be possible. Or is it possible I really had that much velocity swing in hot weather with LG?

Some of the rounds did fail to lock the bolt back, and some did seem to be “hot” but other than that brass shows no major pressure indications.

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dellet
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Re: Lil Gun Hot Weather Chrono, just checking

Post by dellet » Thu Jun 23, 2022 12:36 pm

Lil’gun can erratic, but not 1000fps. 100fps is no surprise.

The low reading might be valid, but would have been real low On the target to confirm. The other two would have blown primers.

First thought would be batteries but have actually never used a Magneto speed, so they may not even use them.

You didn’t mention barrel length, maybe picking up debris? That has been a problem with short barrels and dirty powder.

Are there settings for velocity ranges? Pistol vs rifle?
LabRadar has this problem around 1700 fps. Bottom end of range for rifle and top for pistol

Other than that make sure it’s strapped on tight.
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AccelR8
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Re: Lil Gun Hot Weather Chrono, just checking

Post by AccelR8 » Thu Jun 23, 2022 4:01 pm

Oh, barrel length. Kinda forgot that. 16.5 inch.

The battery is good. This Magnetospeed has no setting for pistol/rifle or anything like that. Just strap it on and go!

Thanks for the reply, Since I've read about "wild pressure spikes" with LG in hot weather, just wanting to make sure my assumption is correct about chrono errors.

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dellet
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Re: Lil Gun Hot Weather Chrono, just checking

Post by dellet » Thu Jun 23, 2022 5:42 pm

Something I had never thought about.
How are you attaching the blade?
To the barrel or a handguard?

If the blade was attached to the barrel, it would move with it. Attached to the hand guard, remain static and the barrel would move independently. Have you used it the same way with other rifles attached the same way? I’d be interested to know if it plays with the readings

I know that plant.one uses one, might be worth a pm.
300 Blackout, not just for sub-sonics.

AccelR8
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Re: Lil Gun Hot Weather Chrono, just checking

Post by AccelR8 » Thu Jun 23, 2022 11:23 pm

Attached to the barrel. Very tight. On the straight, cylindrical part of the barrel right behind the flash hider. The rubber mounting pad is butted up against the FH.

If you can imagine what the Magnetospeed looks like, the bayonet or blade has a curved section. In about the middle of that curve there's a cross-ways mold line. On any rifle, I try to position it so that mold line is about even with the muzzle (or FH) just for consistency.

JimmyBee
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Re: Lil Gun Hot Weather Chrono, just checking

Post by JimmyBee » Sat Jun 25, 2022 10:32 pm

The Magnetospeed has sensitivity levels that work for different velocity ranges...you have to make sure you are on the right setting.

There is also correct and incorrect placement of how close the muzzle is to the bayonet.

Also make sure that it is strapped on tight and that you use the provided square tube to make sure spacing is correct.


If you have a load with a known velocity fire it to check sensitivity settings before shooting for numbers just to make sure you are on and everything is set up correctly.

Low battery could play a roll, it runs on 9v or cr123...... lithium cr123 is best bet (Especially in cold weather) but 9v can be cheaper. (Don't store it with the batt inside long term)

There should be a pdf you can download and look through on their website that shows the above setup explanations.

No affiliation with the company..... but i have used one a decent bit.

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