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What is acceptable grouping at 20 meters?


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#1 Boeruine

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Posted 24 May 2014 - 09:54 AM

So I finally got everything in for my LM4 to match it up with my real steel counterpart. Put everything together, threw the new Vortex SPARC II on top and went into the yard to zero it. I figured I'd start at 20-25 meters and see how it compared the the POA/POI of a real AR15 within CQB distances.

Shooting 4 rounds at a time from a sandbag on the table I really couldn't get an acceptable grouping to even tough the red dot settings. I'm using an 18x24 sheet of paper with one inch grids and over 24 shots I have 16 1/2 inches of variance in width and 13" in height. Seeing as I get about a 4 inch grouping with my KSC M19 I would imagine that there is something in need of some help with the LM4. I am using .25 grams with no wind. I can definitely see them moving left and right through the red dot as I engage the target. I haven't tinkered with the hop up at all.

Any suggestions?

#2 StealthTaskForce

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Posted 24 May 2014 - 12:11 PM

Tinker with the hop up. Lol

#3 Larry

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Posted 25 May 2014 - 12:16 AM

I take 2 or 3 inch groupings at 20 meters to be good, maybe a stray or 2 (couple xtra inches) out of a dozen shots.  Make sure hop up is shooting level, good clean barrel and decent BBs. If still not getting there make sure fps is steady and try a different bucking. My sons Top Tech didnt shoot good when new no matter what I did. Noticed a spot half way down the inside of the brass barrel towards the top?  A new Madbull barrel got it where it needed to be. Hope this helps.

#4 Chuck S

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Posted 25 May 2014 - 04:32 AM

About 30 meters (I need to remeasure).  Bench but hand held, no sandbag, etc.  0.32 Elite Force biodegradable BBs.

LM4:

Posted Image

RM4 at same range.  New barrel installed since this photo, but not shot for groups yet.

Posted Image

-- Chuck

#5 gcw360

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Posted 27 May 2014 - 03:13 PM

View PostChuck S, on 25 May 2014 - 04:32 AM, said:

About 30 meters (I need to remeasure).  Bench but hand held, no sandbag, etc.  0.32 Elite Force biodegradable BBs.

LM4:

Posted Image

RM4 at same range.  New barrel installed since this photo, but not shot for groups yet.

Posted Image

-- Chuck
Chuck - I just put the KM Head in my RM4 and used it at LC XIII. I got more kills with that gun in the morning of the first day than in the previous two LC's combined! Several where at least 200 ft. Let us know what type of groupings you get as soon as you can.

#6 Chuck S

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Posted 28 May 2014 - 02:49 AM

I'm tied up with 5.56mm thru June.  Airsoft will take a back seat for another month.  I have a KM Head barrel for the LM4 on the shelf (still!).

-- Chuck

#7 gcw360

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Posted 28 May 2014 - 10:26 AM

View PostChuck S, on 28 May 2014 - 02:49 AM, said:

I'm tied up with 5.56mm thru June.  Airsoft will take a back seat for another month.  I have a KM Head barrel for the LM4 on the shelf (still!).

-- Chuck
No worries....all in good time.

#8 Boeruine

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Posted 22 June 2014 - 01:11 PM

Finally was able to get back out there and tinker with things after cleaning the barrel etc. Things looked much better this time around, and I think in part it is due to the BB selection. I had been using Evike .25 biodegradables, and noticed a drastic increase when I switched to Airsoft Surgeon .25's just in watching trajectory over the backyard, shooting while observing over the red dot. I plan on giving BB Bastards .3's a shot, but forgot to order them last week. The biggest thing I am not used to is trying to figure out what distance to get a zero at. I am used to a 50 meter zero on my M4. I am thinking since I will mainly be shooting a 1/3 scale steel and IPSC targets I will start at a 50 foot zero, and see if that gets me pretty close to real steel POA/POI. Here were the basic results shooting from a bench:

50 Foot zero- two strings of 10 shots

Posted Image

10 Shots aiming 2" high at 25 feet

Posted Image

I ordered the high power bolt this week from KWA, and thinking about picking up the KM Head barrel to tighten things up even more. Does the KM work with the stock hop up, or should I also upgrade to the EVO II at the same time?

#9 gcw360

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Posted 22 June 2014 - 01:56 PM

View PostBoeruine, on 22 June 2014 - 01:11 PM, said:

Finally was able to get back out there and tinker with things after cleaning the barrel etc. Things looked much better this time around, and I think in part it is due to the BB selection. I had been using Evike .25 biodegradables, and noticed a drastic increase when I switched to Airsoft Surgeon .25's just in watching trajectory over the backyard, shooting while observing over the red dot. I plan on giving BB Bastards .3's a shot, but forgot to order them last week. The biggest thing I am not used to is trying to figure out what distance to get a zero at. I am used to a 50 meter zero on my M4. I am thinking since I will mainly be shooting a 1/3 scale steel and IPSC targets I will start at a 50 foot zero, and see if that gets me pretty close to real steel POA/POI. Here were the basic results shooting from a bench:

50 Foot zero- two strings of 10 shots

Posted Image

10 Shots aiming 2" high at 25 feet

Posted Image

I ordered the high power bolt this week from KWA, and thinking about picking up the KM Head barrel to tighten things up even more. Does the KM work with the stock hop up, or should I also upgrade to the EVO II at the same time?
Can you indicate the max spread, up/down right/left, in inches or cm (I have no preference)?  Thank you.

#10 Boeruine

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Posted 22 June 2014 - 05:07 PM

At 50 feet spread was 4 inches in height by 3 inches in width.

#11 gcw360

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Posted 22 June 2014 - 07:22 PM

OK, thank you.

#12 Chuck S

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Posted 23 June 2014 - 03:09 AM

Measuring shot groups by group size -- extreme spread -- only tells us what the two worst shots did and nothing about the rest of them.  If I get some time I'll try to compute the mean radius of some groups which with factory loaded rifle cartridges is usually about 1/3 the size of the extreme spread.  That is if the group is 3" the mean spread is about 1".  Yeah there will be flyers but mean radius is a better prediction of accuracy.  Not sure what it'll come to with the LM4 or another airsoft.

Computing mean radius takes a little time but I just found the LM4 target I posted earlier and will do the computation tonight (hopefully).

BB selection has a very great effect here from what I can see and there are probably hundreds of choices.

-- Chuck

#13 Chuck S

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Posted 23 June 2014 - 03:11 PM

Forgive me for posting this LM4 group from last summer again.  30 Meter shots.  But I computed mean radius from the actual target tonight.

Posted Image

The group size, the distance between the two worst shots is 3.25".
The mean radius the average distance from the group's center is 1.25".

Once the sights are adjusted to move the the group center to match the point of aim (with these BBs at this temperature etc. etc :) ) this gun should be expected to put all shots to an average of 1.25" of point of aim at 30 meters.  Tells us a lot more than just the group is 3.25".

-- Chuck

#14 Boeruine

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Posted 23 June 2014 - 06:09 PM

View PostChuck S, on 23 June 2014 - 03:09 AM, said:

Measuring shot groups by group size -- extreme spread -- only tells us what the two worst shots did and nothing about the rest of them.  If I get some time I'll try to compute the mean radius of some groups which with factory loaded rifle cartridges is usually about 1/3 the size of the extreme spread.  That is if the group is 3" the mean spread is about 1".  Yeah there will be flyers but mean radius is a better prediction of accuracy.  Not sure what it'll come to with the LM4 or another airsoft.

Computing mean radius takes a little time but I just found the LM4 target I posted earlier and will do the computation tonight (hopefully).

BB selection has a very great effect here from what I can see and there are probably hundreds of choices.

-- Chuck

The 4x3 group size was specifically from Picture #1 from post 8. Blue hash marks are the first string of ten shots. Red hash marks are the second set of ten rounds after making a 6 right / 3 down shift on my SPARC II. Point of aim for all shots was dead center of the pasty. The larger "grouping" was my second group (red) and measured the aforementioned 4 inch high by 3 inch wide group. The first grouping (blue) was slightly tighter. I am used to zero'ing at 50 meters with my actual long guns and having a 5 round group be about an inch.

#15 Chuck S

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Posted 24 June 2014 - 03:05 AM

A 200 meter battlesight zero with the M4 Carbine has an initial trajectory crossover at 50 yards (mixed units of measure I know).  From a prone supported position this rifle and service/commercial 5.56mm NATO ammunition should put all shots in a 1" circle (mean radius of about 1/2").  The trajectory will keep the bullets within 2" of line of sight from just beyond the muzzle out to about 220 meters.  Unfortunately our airsofts can't come close to this accuracy but can still hit a mansized target.

Shots in the A-zone on these type targets, like the groups above, are good regardless of group size or gun.  Especially if they're quick shots from a moving posture or low ready.

Posted ImagePosted Image

The myriad of variables in airsoft (hopup, BB mass, etc.) make determining exactly how tight we can keep our shots quite diffucult.  Since the use of my airsoft guns is exclusively to maintain gun handling skills with service weapons (OK, and chasing whitetails out of the back yard!) I'm looking to maximize accuracy out to probably no more than 50 meters and then determining how close it is to the M4 carbine.  This means right on at 50, an inch low at 25, and 2" low at  10.

Very time consuming process so sharing results is helpful.

-- Chuck




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