So you want to make a knockoff of the famous Remington model 551 semiautomatic rifle and you want to use the identical model number? For 15 years. I was chief trademark counsel for Winchester, so I know how Remington will react . Unless they have recently gone soft, they will be all over you until you stop using "551" or you work out some sort of licensing arrangement with them, which will include quality control oversight by them of both you and your Chinese supplier. And, that won't come for cheap, but rather will be very expensive because you are trying to ride their famous coattails. As I said, I used to sue people like you for Winchester and over 15 years never lost a case, primarily because the infringers were nearly always small businesses and individuals who could not afford to fight the world's best-known guns and ammo company. It is apparent to meet you are small potatoes and Remington will stomp all over you if you use "551.0" in this way. Are they right legally? Maybe yes and maybe no, but it will not matter when they come after you , because you cannot afford to fight them. You want to pick your battles carefully, and this is not one you want to fight. Business practicalities outweigh any legal considerations on this.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
It's a truism that Chinese products are of inferior quality to those they copy, and they have no qualm about counterfeiting well-known and valuably trademarked and copyrighted products made by US businesses. China has virtually no enforceable IP law, so these Chinese manufacturers don't fear legal exposure. They sell to US wholesalers and retailers and are confident that they'll never be sued in the US, where they have no assets, or in China, where no law enforcement exists to stop them.
Branded or not, if the "trade dress," in shape, color, silhouette, etc. of packaging confuses consumers about the actual source (and it just needs to be confusingly similar to confuse consumers, it doesn't need to be an exact copy), then it's trademark infringement. And if you traffic in infringing goods, expect to be sued by the trademark owner sooner or later.
Avvo doesn't pay us for these responses, and I'm not your lawyer just because I answer this question or respond to any follow-up comments. If you want to hire me, please contact me. Otherwise, please don't expect a further response. We need an actual written agreement to form an attorney-client relationship. I'm only licensed in CA and you shouldn't rely on this answer, since each state has different laws, each situation is fact specific, and it's impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue.
If you intend to contact the manufacturer of the brand name rifle scope [which is, I think, L-3 Communications Eotech, Inc.] then you and your own trademark attorney first need to review the registrations Eotech owns that protects the trade dress [i.e., the ornamental appearance] of its "551" rifle scopes. Visit the links below. And note that its registrations apply to "firearms sights" and is NOT limited to only scopes affixed to rifles that shoot metallic bullets. Good luck.
The above is general information ONLY and is not legal advice, does not form an attorney-client relationship, and should NOT be relied upon to take or refrain from taking any action. I am not your attorney. You should seek the advice of competent counsel before taking any action related to your inquiry.