Posted: 3/23/2026 9:29:17 PM EDT
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New to striker fired P320, the red dot was bouncing all over the place when sighting in. Then I notice this large frame to slide movement when taking up trigger prior to release. The rear end goes downward and the front end of the gun goes upward. This can't be right, is it? What can be done?? P320 |
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Is this with a magazine in place or loaded? If not put a mag in it. My commercial gun has slop until a mag or loaded mag is in place. The military guns are solid with or without |
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Yes, it's normal. I noticed the same and asked a similar question a while back. People mentioned its the play in the slide when no upward pressure is being applied by a loaded magazine and the (unsure of proper terms) internal parts are doing their thing when pulling the trigger. |
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This cannot be normal, otherwise it is impossible to sight in the firearm. You would never be able to be even reasonably accurate. You would never be able to know where the slide would be pointing at the time of Firing…… There has to be some solution even if it means a new slide, FCU etc. |
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It’s just how the 320 seems to be. Loaded they seem to work fine and the up/down thing goes away. FWIW, I think the barrel is the solution. I say that because my M18 is a GI gun and has none of this bobble. If I put a commercial P320 3.9” barrel in it the wobble thing happens. Replace the GI barrel and it is tight all over. My M17X had the bobble thing like you describe but sighting the attached M17 Romeo was no problem. I was able to get a GI M17 barrel and now like magic all movement and bobble is gone just like on the M18. That tells me the cam/locking of the GI barrel is different enough to tighten the whole pistol up on my sample of 2 guns. YMMV |
“You either know and understand history or you trust the government. You can’t do both”
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Originally Posted By BigM: This cannot be normal, otherwise it is impossible to sight in the firearm. You would never be able to be even reasonably accurate. You would never be able to know where the slide would be pointing at the time of Firing…… There has to be some solution even if it means a new slide, FCU etc. Load magazines with ammo and shoot it. What is your zero process? Are you using a laser bore sighter? |
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Originally Posted By scottrh2: It’s just how the 320 seems to be. Loaded they seem to work fine and the up/down thing goes away. FWIW, I think the barrel is the solution. I say that because my M18 is a GI gun and has none of this bobble. If I put a commercial P320 3.9” barrel in it the wobble thing happens. Replace the GI barrel and it is tight all over. My M17X had the bobble thing like you describe but sighting the attached M17 Romeo was no problem. I was able to get a GI M17 barrel and now like magic all movement and bobble is gone just like on the M18. That tells me the cam/locking of the GI barrel is different enough to tighten the whole pistol up on my sample of 2 guns. YMMV Now that is interesting…. |
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Originally Posted By scottrh2: FWIW, I think the barrel is the solution. I say that because my M18 is a GI gun and has none of this bobble. If I put a commercial P320 3.9” barrel in it the wobble thing happens. Replace the GI barrel and it is tight all over. My M17X had the bobble thing like you describe but sighting the attached M17 Romeo was no problem. I was able to get a GI M17 barrel and now like magic all movement and bobble is gone just like on the M18. That tells me the cam/locking of the GI barrel is different enough to tighten the whole pistol up on my sample of 2 guns. YMMV Someone explained a couple years ago that the GI models use a pretensioned barrel that has a tighter lockup to improve accuracy. They appear to be matched by hand at the factory. I can confirm that based on how tight the fit was when I swapped barrels between two GI M18 slides. My M17 and two M18s have almost zero play between the slide and frame, while my commercial pistols have that slight up and down tilt from front to back and wiggle just a little side to side. |
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It is not like a 1911 where the slide and frames rails have tight tolerances and the rails are long. 1911:  Just the 4 bent tabs on the FCU, all located on the back half of the gun:  Then the slots on the slide that are taller than those tabs are thick:  So without a loaded mag pushing the slide up, it can / will move during the trigger pull. Some think this may contribute to the UDs. |
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I had the same issue when sighting in a commercial gun (with a loaded mag in it). I have sighted glocks in to be like laser beams. My P320 was either mechanically inaccurate as all get out or this slide movement was bamboozeling me. I had to bench the gun and pull the trigger all the way to the point of break very carefully. I think the commercial guns are simply inferior in terms of barrel fitment. Otherwise i don’t know how the M18 and M17 could pass the acceptance test accuracy requirement. |