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Posted: 4/17/2009 1:02:53 PM EDT
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A buddy of mine put a DTI upper kit (20' flat top) on a Spikes lower. If the bolt carrier is being held by the bolt holder and he hits the but of the rifle on the ground it releases the carrier and if a mag is inserted a round is chambered (the bolt holder was not depressed). He noticed this when setting the rifle down harder than me meant to one time. Is this supposed to happen or did he assemble the lower improperly?
What is concerning him is that when he unloaded the rifle the primer had a very shallow dent. There was no discharge, but it made him nervous. Is this normal as well? If not how does one rectify the problem? |
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Normal. The bolt-catch is spring loaded and is held in-place when mags are replaced, ect. by tension from the buffer-spring.
If he slams the butt down with a loaded mag in the weapon, that tension is released as the spring is compressed by the BCG's weight. The effect is the same as pulling back on the charging handle. The firing-pin has no spring, it is free-floating. It will dimple primers. This is also normal and shouldn't be of concern, but still not a great thing to be doing in-doors just as a safety point. *I chose not to be an ass and post the picture of the BCG group with FP spring and ask the OP to check for it. |
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Quoted:
A buddy of mine put a DTI upper kit (20' flat top) on a Spikes lower. If the bolt carrier is being held by the bolt holder and he hits the but of the rifle on the ground it releases the carrier and if a mag is inserted a round is chambered (the bolt holder was not depressed). He noticed this when setting the rifle down harder than me meant to one time. Is this supposed to happen or did he assemble the lower improperly? What is concerning him is that when he unloaded the rifle the primer had a very shallow dent. There was no discharge, but it made him nervous. Is this normal as well? If not how does one rectify the problem? Anytime you chamber a round and don't fire it, there will be a very small mark from the firing pin. Nothing to worry about, but I don't know how often you'd want to do that to a single round. |
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Quoted:
Normal. The bolt-catch is spring loaded and is held in-place when mags are replaced, ect. by tension from the buffer-spring. If he slams the butt down with a loaded mag in the weapon, that tension is released as the spring is compressed by the BCG's weight. The effect is the same as pulling back on the charging handle. The firing-pin has no spring, it is free-floating. It will dimple primers. This is also normal and shouldn't be of concern, but still not a great thing to be doing in-doors just as a safety point. *I chose not to be an ass and post the picture of the BCG group with FP spring and ask the OP to check for it.  Funny.
Thanks for the info. I never banged the but of my rifle on the ground very hard, and didn't want to try it with mine in case I put mine together wrong too, and have a negligent discharge, and I didn't have time to go to the range and try it out. |
As already mentioned, the dimple on the primer that occurs when chambering a round is normal. The dimple is miniscule compared to that caused by the actual firing of a round. The picture on the left below is from a fired cartridge. The picture on the right is from a chambered, but not fired cartridge.
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| I can only add one thing.. Safety concern.. You already know a round can be chamber by simply hitting the buttstock on the ground.... IMO If you are going to have a loaded mag in the rifle and are not on the firing line getting ready to fire it ... Do so with the bolt in lock up. Not to the rear, resting on the bolt hold open for this very reason. You have to push aillte hard to get it to seat in there.Just don't want know body to get their head blown off. All you have to do is charge the handle and you then loaded... Also the military using harder primers just for that very reason. ( the light firing pin strike... ) . To help insure no Accidental Discharge... Free floating firing pin deal.... Enjoy... WarDawg |
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