KrisS

I have Holosun 510c on my Bul SAS II. I use Tevo Sports mount although I believe there are also other companies that make such mount (Limcat ?). The key thing is which holes pattern you have for the mount. I believe the Bul mount pattern (at least those sold in Europe) is 3 holes with metric screws (imho it is not compatible with standard US 5 hole pattern but I am not sure). I believe Tevo had mount blanks without holes drilled so you could get such and ask your gunsmith to drill it.

I have 507c and 510c since roughly 2 years. They were both used on Open Gun, Ar-15, 9mm PCC, and on slide on 9mm pistol. They work great, are durable and never had any issue with them. Mechanically and functionally very reliable Red Dots.

In general as guys said already: wait with changing anything for a moment. As for the red dot - I would change it for something smaller with relatively big window or even Holsoun 510c (tevo sports makes nice mounts for it) IMHO load is one of the key elements . I was Using VV3N38, Vectan SP2, Lovex 37.1 and currently RS24. Vectan leaves hard black residue on the parts slowing down mechanisms after 400-500 shots, 3N38 has availability and pricing problem (at least in my Country), Lovex is cheap available and its only problem is stability and "copper like" remainings inside pistol, RS24 seems to be atm the best working powder for me (at least with CMJ 123gn 0,356 from LOS) The key for dot stability IMHO apart from Red Dot flex could be the load, 164 PF is ok from the perspective of IPSC rules but Comp in my gun works best around 168-170 PF making the gun stay flat. You have to try which combination works for you as apart from the pistol and load your grip may do the difference (thats the reason to wait with the changes until you will familiarise with new platform and will see what gripping method is best for you - thumb position on the safety and on the thumb rest is IMHO crucial)

I have BUL SAS II UR Open and my reloads / ammo depending of bullet type OAL is either 30mm or 30,5 mm. As "regular" 9mm is 29,69 mm then I would say it accepts longer OALs (unless they changed their barrel parameters for US then I'm wrong). A lot in terms of OAL depends of bullet shape anyway. You can ream the barrel throat if you need to. With OAL of 30mm and soft plated LOS 124 gn bullets there is roughly 3mm of bullet that sits in the brass. I see no reason to go longer if there is not signs of overpressure at PF of 170-175.

That was jcv industries mount (with trijicon rmr mount pattern). Currently I have 507c on other gun (cz sp-01 shadow) and bul is equiped with holosun 510c. Overall very satisfied with holosuns

Imho what keeps the bullet is mostly neck tension. Although in major ammo where oal is longer and bullet sits very shallow additionall crimps helps a little (but maybe not much). On cmj bullets I use when I apply more crimp there is a „step” that holds bullet in place and prevents (maybe marginally) the bullet setback. If he changes crimp and there is a change in the 1shot pattern then it is ammo related. Changing ammo to different kind /make would be even better of course. I could be wrong though. That’s just unconfirmed theory

Maybe your ammo has too shallow seting depth or to weak crimp. Maybe while loading first round the bullet is pushed deeper than during all other shots. You get higher speed of the first shot and higher poi ? Just a theory. You could use different ammo or crimp yours stronger ?

In Poland cheapest open version is 3,6k$ (with vat tax). Bulesteros is 6,7 k$ taxed as well.

I also have some ammo (like 2% of batch) that does not fit into the chamber just after it is done (cmj bullets have size variations and rub rifling on the sides with 0,356 bullets or mixed brass I use reacts not so good to format). I fix like 75% out of that with Lee Factory crimp die. After that they usually fit into chamber

I have the BUL SAS II UR OPEN. Concerning the magazines you just need to buy Para version. Overall it is very nice gun. This one is a little bit "corrected" comapred to stock version (different mount, Holosun 510c, thumb rest and AA shielded safety). Shoots great out of the box.

I had similar case on 2011 platform and I've found the potential reason / or set of conditions when it happens. I used slowmotion recording with iphone to find out what was the reason and here are my findings: Hitting the right/bottom corner of the mount (and/or empty brass is pushed back in the port on top of next round) when I use some pickup brass, During the ejection the brass is not properly held by the extractor and it goes up instead of low 4 oclock (as my ejector is cut to hit brass back on top and direct it right and back).Brass either hits the returning top of the slide or bottom right corner. Then the brass goes back into port if the slide return too slow or just bounces away "just" hitting the mount with random ejection pattern. Changed extractor to aftec type extractor which helped a little. I will check the stronger and weaker return spring (with DPM it is quite easy) to see what will be the outcome. Current temporary fix is just some tape on the mount corner.

I have tested also other loads with 124 grain bullets and Lovex 37.1 : DMA Reloading FMJ RN 124 gn (OAL 30,10 mm, 9,85 gr for 165 PF), Frontier RN CMJ 124 gn (OAL29,80 mm, 9,82 grn, PF 164) and Frontier CMJ RN MATCH 124 gn (OAL 30,00 mm 9,82gn 164 PF).Again: test it and use it at your own risk. The only complaint on FMJ vs CMJ is FMJ makes compensator very very dirty compared to CMJ.

This is what works for me but you need to be careful and use it at your own risk. Gun: BUL SAS II UR Open OAL 30,0 mm Lovex 37.1 9,9 grn LOS Bullet CMJ RN 123 grn SP Fiocchi primers Medium crimp It makes 167 PF easily Good amount of gas to run the comp, relatively clean but hard to load. Soft kick, better than Vectan SP2 or VV3n38 I am very happy with it

It still works great. Only the back of the optic is beat up more as sometimes the brass hits it when bouncing from the top of the slide. It happens for some of the brass only but as I am reloading based on picked up brass I am aware of this. As for the photos of the mount itself: it was too low and I had to file the bottom of it so there is a celarance

I mostly shoot 9mm Major and my gun is tuned for it (DPM spring system). at the very begging of my use it was shooting "regular" purchased ammunition with stock 9lbs spring just fine. I tested that with 124gn and 139 gn RN bullets with D032 load as well. Did not have any issues with it but it is temperature and lube dependant as well. With minor loads and temperatures below freezing point the slide became a little lazy and once or twice it felt slow but still was cycling nor had double feed issues. Unless Major ammo is not available at your location what is the sense to use minor ammo in a gun that shoots Major PF? I try to stick to one load to have the gun behave same time on trainings and during the matches. You could tune it for minor loads only of course as well.

Yes it is possible technically still IMHO this is not the optimal approach. There is no regular rear sight so you could use the slot for racker for the mount but then you would have to make custom red dot mount with the integrated racker for specific type of sight. The questions are: - if you will like red dot moving with the slide - how long red dot will be operational and hold zero due to recoil - will you be able to mount something bigger like Holosun 510C on the slide ? - how racker function on the mount will make the mount move/lose zeroing - will you need another custom mount if you decide to change red dot type / mounting pattern - what about thumb rest ? - how additional weight (red dot + racker + mount) will influence slide speed / timing of the gun So looking at that making holes for the mount gives you more functional benefits and flexibility in the long run. So yes it is possible but IMHO that would make criplled gun. Bul originally has 3 holes angled and I wanted to have flexibility and access to various mounts and thumbrest. Making 5 holes for the mount seems to be easier than going fully custom with doubtful functionality. Just my opinion.

Depends of temperature: light oil everywhere when it is cold (and slight amount of grease on barrell lugs) or 0W40 oil during summer everywhere (plus small amount of grease on lugs). I oil gun every 200-400 rounds anyway to keep it run flawless. The fact I do not use a lot of oil to keep red dot glass clean - just thin film will do.

What was used for lubrication ? Due to tight fitting I usually use oil on rails and barrell and small amount of light grease on lugs and slide stop. When it is warm thicker oil is used (to stay on slide and barrell longer) when it is cold light oil. Check if gun is assembled properly and if nothing rubs "more than it should". As slides starts to feels sticky does the gun still works as it should (fully cycles, ejects brass properly, etc) ?

So after 1st match with new optics the impression is great ! I was initially concerned with the additionall weight, unscrewing the mount, brass ejection, dot dancing like crazy due to weight etc but.....nothing like that happened After mounting it as any other optic with red loctite (put some nail enamel check marks on the heads of the screws to see if it is unscrewing) after roughly 700 rounds I can say this setup works as expected and is awsome ! Although it is big due to window size mostly and sits a little bit higher than my previously mounted red dot plus it is a little bit heavier, those are not issues in real life at all and the benefits for me are: - really easy to find the dot even with one/weak hand shooting from some unusuall positions. - transitions are much easier as you can see the dot moving to the target you will be shootiong earlier so less time wasted trying to "find it" - ejection pattern is fixed after small modification/tuning of ejector - so zero stovepipes / ejection problems so far. - all the benefits of different reticles (I shoot mostly the circle only but the dot is also fine in yterms of size/brightness - tested by trial) Wondering how it will hold in the long run but this is not real concern atm. I am very satisfied !

OK so I wanted to change the ejection pattern and adjusted the angle of the ejector. Now no ejection issues, ejection pattern is lower and more to the back (around 4pm) and brass rarely hits the red dot. There are tow cases when it happens: if the splits are sub 15-17 ms and slide starts to come back too early and brass bounces from the back of slide and then from the back / edge of red dot or as I am using the different pickup brass when the brass is somehow used / in bad shape. Overall I am vey satisfied with this setup. We will see how it will behave in longer run Link to video with current ejection pattern https://i.imgur.com/7cYKz0N.mp4

So after 200 rounds I can say I am very satisfied. The brass slightly dings the very corner of the red dot but that does not cause any ejection issues so far. Monday will have more oppty to shoot on level 1 IPSC match so will have more info to add. Here is link to video how it shoots: https://imgur.com/2urrW6J

After a little bit of filing managed to mount 510c on my gun today. Tomorrow will be first test. My only potential concern are extraction issues. I'm a little bit surprosed by the size of the window

The residue from last photo is not from Lovex - it is from Vectan SP2(as described). Brown flakes from earlier photo though are remainings of 37.1

I am using regular Fiochi SP primers. They are priced well, available, have no issues using them etc and they seem to be doing good job in all my 9mm Major loads. The gossip says the Explosia was making the AA7 for American market. Not sure is it true or not but as I am located in Europe Lovex with various powders is IMHO one of the most commonly used powder in Poland, Czech and Slovakia (availability, proce point, various powders range etc). The feature of Lovex 37.1 (apart how it shoots, measures, etc) I like a lot is easy cleaning compared to vectan SP2. Lovex leaves unbrnet brown particles all over inside of the gun but it does not leaves the solid residue. One thing I am not sure yet is its temperature sensitivity and how it influences PF and pressure . Sometimes in winter I shoot under 0 celcisus / freezing point and in Summer it might be +35 Celcius. Below is example what Vectan SP leaves inside and outside gun:

I used Lovex and two other powders for IPC 9mm Major load with CMJ 123 gn LOS bullets (165-167 PF): 1. 3N38 - meters relatively well, shots soft but it requires compressed loads and it is hardly available and pricey in my location plus it fills case almost full so I got a lot of spills (OAL 30.00 mm ; 8,05 gn of 3N38) 2. Vectan SP2 - meters terribly, leaks plus is static electricity sensible and then measurements are +- 0,1 gn, leaves dark hard residue in the gun which requires cleaning more often, leaves rougly 3-4mm from the case rim - so almost no compression, shots nice but it seems there is too little gas but it shoots flat, mid prices issues with availabilioty from time to time (OAL 30.00. 8,7 gn) 3. Lovex 37.1 - meters very good and consitently, if required compresses relatively well, shoots flat and shot impulse is softer than in SP2 but harder than 3N38, leaves no permanent/hard to clean residue in the gun (looks like brown flakes but no dark dirty residue), is relatively dense but you need more of it to get PF, leaves similar amount of space for bullet similary to Vectan SP2 and is available and cheap (in my location). The only downsides with Lovex in general is that they used to have some batches of powder that were not exactly to spceification, but havent seen such case since year or two (OAL 30.00 mm, 9,9 gn Lovex 37.1). Summarising : highly recommending it. Works great and has excellent price/performance for me. This is how the back of the gun looks like after shooting 400 rounds on lovex (looks dirty but is very easy to clean. This is not copper from the brass but lovex remainings):