You should go with DEWALT DCGG571M1 20-volt MAX Lithium Ion Grease Gun or CARBYNE Heavy Duty Professional Quality Pistol Grip Grease Gun. They're both really good.
I have used this one DEWALT DCGG571M1 20-volt MAX Lithium Ion Grease Gun for 2 years now.
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It's very easy to find a good one these day. You can find it on amazon or any auto stores.
I have been trying many of them but the 3M is really good. You should try it first. Read this one https://innovatecar.com/best-headliner-adhesive/ or other to know before purchase one.