Holosun micro red dot feature comparison chart

ABCGLUM and all combinations of them. Confusing isn’t it?

What are the differences between Holosun micro red dot models?

Aimpoint compatible base Solar power Side battery housing (Aimpoint micro style) Circle and 2MOA dot Integrated lens covers Ruggerized frame around turrets 30 m and 30 min waterproof
HS403B x
HS403C x x
HS403GL x x
HS503BU x x x
HS503CU x x x x
HS503GU x x x x
HS515BU x x x x
HS515C x x x x
HS515CM x x x x x x
HS515CU x x x x x
HS515GM x x x x x x


  • A base model without Aimpoint compatible mount
  • B base model with Aimpoint compatible mount
  • C Solar powered model
  • G External battery housing
  • U Ruggerized frame around turrets
  • M Extra ruggerized frame + better waterproofing
  • 403 2MOA dot
  • 503 65MOA ring + 2MOA dot
  • 515 Ring + dot + integrated flip-up lens covers

Cleaning brass with ultrasonic cleaner

Brass cleaning science! We’ve tested three different solutions for cleaning fired brass with ultrasonic cleaner.

The  temperature was set to 50 degrees (Celsius of course, that’s probably roughly 56 to 125 inches in US temperature units, stones or is it nails?) Cleaning time was 15 minutes.

Below in the table you can see the different concentrations used. Every solution was mixed to cost 0.10€. I thought that to be the only viable way to measure different solutions. It would not have been fair to just measure the amount of solution if it’s not feasible to use the most expensive solution in long term use. All mixtures were made to a 125 grams of  35 C° water. This naturally threw difference of the total  amount of cleaning solutions by ~10% as C4+water sums only 127 g and soap+acid+water 150 g. But for the nature of cleaning brass outside of synthetic tests I believe this type of difference is acceptable.

Washing solution Price ( €) Package size (grams) Price per gram Amount in solution (grams) Price of solution
Oregon Ultrasonic 15.9 1000 0.0159 6.98 0.110982
Bore Tech C4 29 473.176473 0.06128791615 2 0.1225758323
W5 dishwasher 1.19 500 0.00238 11 0.02618
Citric acid 0.78 40 0.0195 4 0.078
Mix of acid+soap 1.97 in total 15 in total 0.10418

As you can see the Bore Tech C4 Carbon Remover was used only with ~1.6% concentration. W5 dishwasher soap had to be added relatively huge amount in order to reach even close to what Carbon Remover and Ultrasonic cleaning solvent costs. Most likely lower amount of W5 dishwasher soap would have been sufficient. You can purchase citric acid way cheaper in larger containers.

All brass looked pretty much the same before going into the bath.

Brass were sorted from these three rows to three cleaning containers randomly.

Inside the brass looks pretty bad.

Headstamps were mostly S&B but other brass were also in the mix.

After 15 minutes of cleaning the water had turned to a black musk in every cleaning container.

Let the photos be the judge which solvent won:

From top to bottom: W5+citric acid, Oregon, Bore Tech

It’s clear that Bore Tech C4 Carbon Remover was the most effective on cleaning the outside of the brass. Picture may not show the difference as clearly but nearly all dark spots were gone on brass that was bathed in C4 Carbon Remover, all brass were shiny and uniform color.

Next came the mix of dishwasher and citric-acid. Brass is shiny but slightly tinted toward brown compared to Carbon Remover.

Last place in cleaning the outside came Oregon’s Ultrasonic Cleaning Solution. It left dark spots in most of the brass and it’s even visible in the picture how the brass is darker that with other two contenders.

When comparing inside of the brass there was clear difference between all three cleaning solutions.

Dishwasher soap + citric-acid

16 brass out of 20 were cleaned extremely well with W5+citric-acid. Some were left with dark spots, it’s unclear for me why as when comparing the darker brass with super-shiny all were most likely once fired S&B brass and collected from indoor range. So no moisture contamination should have taken in place.

Oregon Ultrasonic Cleaning Solution

11 brass out of 20 were somewhat cleaned, but none of them came even close compared to W5+acid mix. Some of the “clean” brass in this group might be dirtier than the “dirty” in other groups.

Bore Tech C4 Carbon Remover

Even though Carbon Remover won when comparing cleaning results at outside of the brass it’s not as effective cleaning the inside of the brass than home-made mix of W5 dishwasher soap and citric-acid. 12 out of 20 brass was super-shiny but the rest was left unsatisfying dirty. Notice how there is some black residue around the primer hole where dishwasher+acid left that area cleaner on most brass. Again when checking the headstamps there were no clear correlation between clean and dirty brass. 7 out of 8 dirty brass was S&B and most likely only once fired e.g. factory loads.

All brass in the test were handled with nitrile gloves in order to prevent grease-marks from fingers. Brass was not sorted or selected anyway. Most of the headstamps were S&B. Others were TCS (4pc), G.F.L (1pcs), STV (1pcs) and Geco (1pc). Some brass might have been reloaded (at-least two S&B had different primer than others), but majority of the brass was once fired factory loads. All brass was collected from indoor range so no water or moisture contamination could have taken place which could have baked some of the powder residue to the brass. There were no correlation of cleaning results between different brass whether they were reloads,  or factory ammunition between different companies.

The Ultrasonic Cleaner used in the test was cheap Chinese made 9l Stainless steel made tabletop cleaner. Advertised Ultrasonic cleaning power is 200W but no more than 150W is used from the outlet during cleaning cycle with heating turned off. Brass was placed in three identical thin wall plastic containers and adequate amount of water was added to the stainless steel tank so all three plastic containers holding the 125g water, cleaning solution and brass, started floating. Plastic is not optimal container as it has tendency to absorb ultrasonic waves, but in this test the purpose was not to clean brass as effectively as possible, only to compare different cleaning solution consecrations when their calculated cost was identical.

End result of this test was to continue tests with dishwasher soap and citric-acid. Maybe changing the concentration or adding salt and/or dishwasher detergent to the mix might help cleaning even the most stubborn dirty brass. Naturally cleaning 20 empty shells at a time is not the goal. When cleaning solution mixture is complete the purpose is to clean as much brass as it’s possible to load to the 9 liter (5 yards for you imperial folks) cleaner.

V-S Suomen Talvi SRA 2017

We shot the years first reservist 3gun (SRA) match in Huovinrinne shooting range.

The stages were good with enough challenge and variance.
My biggest failure was not to check the barrel line in small hole, which cost 2 misses and I also shot 1 N/S on my side, but still managed to get second in overall!
( overall  and stage results)

Also I should learn how to shoot pistol, as in stage 1, I shot one unnecessary extra shot to the “close range” target:

You saw right, the target in previous picture is huge!
Due to range restrictions, the targets could be set only to the back berm. This effectively prevents building a stage with close range and long range targets, but luckily the organizer had circumvented this, by applying greatly enlarged targets next to normal size targets 😀

long and close range targets @150m on stage3
another “close range” target

There was also a very nice swinger


SRA SM 2016

SRA SM (Finnish reservist shooting championships) was shot 6.-7.8.2016 in Nurmes. The stages were pretty good and sauna was provided on both evenings (I arrived in friday 5.8.).

Stages and stages drawings are presented below, but the drawings of the stages can also be found  from RESUL and a playlist of all the stage videos is available at https://www.youtube.com/playlist?list=PLT6QbUxcGnXuY4vpAbVsfLsRHMsaq3aeK

More information about the compition in finnish: http://resul.fi/uutinen/sra-sm-2016-rastit-lisatietoja/

Stage1: rifle, from near to far (10-250m)

Stage2: rifle, 10-200m

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Vares Cup II / 2016 gallery

Few pictures from Vares Cup II / 2016 SRA competition.

Speed Cycling and reliability mod for Baikal MP-153

There is always that one particular brand, type or batch of shotgun ammunition that does not work with semiauto shotguns. Some shotguns are more picky than others and even same shotgun models some individual guns cycle same ammunition that other guns struggle with.

For DIY person it’s tempting to fix this uncertainty. Naturally lapping the bolt carrier rails, polishing all metal-to-metal contacts will help the gun to cycle. With gas operated shotguns drilling gas ports slightly larger might also help.

After doing all above I still found that there exists ammunition that does not cycle reliably with my Baikal MP-153.  Mostly really old 24g skeet and trap ammunition. Some may ask that why bother? Those asking that question don’t get the tickling sensation when fixing something makes things better.

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Phillips head screw mod to roller cam pin

Some time ago I acquired a roller cam pin to my AR-15. Gas key had to be machined to match the new round cam pin, but that was not an issue as I had planned to give my bolt carrier some diet in a form of tender milling from my trusted gunsmith. (Final weight for bolt carrier is 173 g.)

My roller cam pin had one problem though. The screw that was supposed to hold the brass roller in place had a tendency to loosen up and then jamming itself against gas key.

Roller cam pin screw loosen up and hitting gas key. Effectively preventing bolt from opening.

Original screw was completely flat, without any screw drives. I did not had adequate tools and strong enough thread lock to hold the screw in tightly.


I contacted the roller cam pin manufacturer and they offered to fix it for me. They apparently have some adhesive to semi-permanently attach the screw to rest of the cam pin.
I, being more of an DIY-guy, opted to fix the roller cam pin myself.
After two iterations I was finally happy with the solution.

Custom made phillips head screw for roller cam pin.

It may not be the best possible steel strength for this particular application, but the brass roller leans against small bulge in the cam pin, so the screw don’t have to take any force coming from side. It just has to hold the roller in place and avoid any contact with gas key.


Time: 1 hour
Tools used: one random M4 screw, hand-file, cordless drill, hacksaw, PH2 head screwdriver and “Extra hard thread lock”

Talvi SRA 2016 gallery

Some pictures from V-S Suomen Talvi SRA, a local reservist 3gun match.

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