Just tried some bump-firing with my new build (J&T 16" kit on superior lower), never tried an AR before but seems to work.

Anyways, after 1 mag I was able to get about 10 rounds off before getting 'out of whack' and having to start over. I could do this for the entire mag. After several reloads and other sporadic plinking, I started getting light strike misfires, chamber a new round and get 3-4 rounds out before another misfire. The primer was obviously not hit as hard, and after collecting all the misfires they fired fine the second time around. It shoots fine under normal conditions, but will no longer 'bump-fire' more than 4 rounds. Any suggestions?

thanks!

Don't bump fire?  Or, get the special lower that has the "bump fire" selector switch.

Bumpfire is certainly a vicious way to pop the cherry on a new build.  

The firing pin will dent every primer upon chambering.    I would search troubleshooting and inspect your build (trigger group?)

Quoted: Just tried some bump-firing with my new build (J&T 16" kit on superior lower), never tried an AR before but seems to work. Anyways, after 1 mag I was able to get about 10 rounds off before getting 'out of whack' and having to start over. I could do this for the entire mag. After several reloads and other sporadic plinking, I started getting light strike misfires, chamber a new round and get 3-4 rounds out before another misfire. The primer was obviously not hit as hard, and after collecting all the misfires they fired fine the second time around. It shoots fine under normal conditions, but will no longer 'bump-fire' more than 4 rounds. Any suggestions? thanks!

Dont bump fire? If you want that, save your $ and buy a RR.

Or get an AK!!!!!

Quoted: Quoted: Just tried some bump-firing with my new build (J&T 16" kit on superior lower), never tried an AR before but seems to work. Anyways, after 1 mag I was able to get about 10 rounds off before getting 'out of whack' and having to start over. I could do this for the entire mag. After several reloads and other sporadic plinking, I started getting light strike misfires, chamber a new round and get 3-4 rounds out before another misfire. The primer was obviously not hit as hard, and after collecting all the misfires they fired fine the second time around. It shoots fine under normal conditions, but will no longer 'bump-fire' more than 4 rounds. Any suggestions? thanks! Dont bump fire? If you want that, save your $ and buy a RR.

Yeah, cause if you're gonna waste 30rds of ammo in 3 seconds, you should spend $14,000 to do it and stop cheating with a $650 rifle

WIZZO

Next time try letting off the trigger, then pulling it again, some times when I bump fire the hammer gets under the disconecter with the hammer pulled. See what I meen?

Quoted: Bumpfire is certainly a vicious way to pop the cherry on a new build.   The firing pin will dent every primer upon chambering.    I would search troubleshooting and inspect your build (trigger group?)

It did have a few hundred rounds thru it before I attempted bumpfiring. I don't understand about the denting the primer...  this isn't a little scratch or anything, the primer has been struck, only about half as deep as the rounds that went off.

Jimmy- Yeah, I thought that might be it at first, but no luck. It's as if it were a dud or dryfired. The trigger doesn't reset and I have to chamber a new round to fire again.

Your gonna shoot your eye out.

Quoted: Your gonna shoot your eye out.

and we all know thats when the fun and games end.

WHAT THE FUCK YOU DO.

Quoted: Quoted: Bumpfire is certainly a vicious way to pop the cherry on a new build.   The firing pin will dent every primer upon chambering.    I would search troubleshooting and inspect your build (trigger group?) It did have a few hundred rounds thru it before I attempted bumpfiring. I don't understand about the denting the primer...  this isn't a little scratch or anything, the primer has been struck, only about half as deep as the rounds that went off. Jimmy- Yeah, I thought that might be it at first, but no luck. It's as if it were a dud or dryfired. The trigger doesn't reset and I have to chamber a new round to fire again.

Following the 4 rules:
Chamber a live round, extract it, see the dent.

Quoted: one of two things is happening with your rifle kbeefy. either your hammer is falling during the battery stroke or the carrier is rebounding enough to cancel the hammer blow. one is a timing problem with the FCG and the other is a problem with the cyclic rate which can be corrected by modifying the gas system or the the recoiling parts.

While watching a couple video clips we made, I did notice that the firing rate was much faster when I was having trouble, earlier in the day when things seemed to be working fine it would fire much slower.


This seems to be a topic of much debate...  I didn't realize there was such a large difference between an AR and a M series rifle. Or maybe between bump-firing and AR and FA a M series.

Howdy.  

had my colt 6721 since Xmas '04, been tring to perfect bumping ever since.  what I have learned is that with a stock trigger I can really only use hot surplus XM193 or XM855, otherwise the disconnect grabbing the trigger happens every time.


But with a friends light JP trigger I can bump with light recoiling wolf ect. easily. and the cyclic rate of hot stuff is scary fast.  you will occasionaly get failures to feed or extract ect. but I feel a light trigger is the key.


One huge benefit of a light trigger is the reduction of group size while bench shooting

BTW.  My JP is on the way.

What I think is happening is that the hammer is following the bolt carrier on its way forward. This is happening because the disconnector was tripped by the trigger (bumping the trigger actually resets and trips the disconnector before the bolt carrier fully cycles) before thecarrier/bolt has time to go fully forward and lock. The hammer "rode" the bolt carrier as the bolt carrier was moving forward and the hammer lacked the inertia to hit the firing pin hard enough to fire the primer. I suspect that if you look on the outer edge of the firing pin where the hammer contacts it you will find it to be slightly roughed up. This is coming from where the hammer followed the bolt carrier in and  the hammer contacted on the underside of firing pin head instead of on the center of the firing pin head. Also since the hammer "rode" in on the firing pin it reduces the  force it transfers to the firing pin reducing the primer strike force. I have an AR with an adjustable gas tube and it bumped fine until one day I had a live round left in the chamber with the light primer strike while bumping from the shoulder. I noticed that the rate of fire was higher that day just before the problem started. Also it was slinging shells out much further. I checked and my adjustable gas tube set screw had backed out. I ran it back in to my normal setting and it bumped fine again. I also discovered that it is more prevalent if you bump from the shoulder. I also bumped a Daewoo K1A1 (gas tube operated not piston operated) and it did this when I bumped from the shoulder (worked fine from the belt loop). The K1A1 has a fast cyclic rate like an normal (unregulated) AR. I then bumped my SAR 3 (.223 AK) both from the belt loop and the shoulder with no problems of this type. The SAR 3 has a much slower cyclic rate than an AR I suppose because it is the AK has a piston drive and more mass to move. I have had the bolt carrier stick back open because  the disconnector tripped and caught the carrier (trigger cycled before the carrier started back) on the SAR 3 (weak disconnector spring I found out ). I also found marks on the underside of the firing pins on both the AR and the K1A1 that evening when I had trouble with the light primer strikes.  I had never noticed this when cleaning them before. Also all of the ARs that have been bumped that I have checked have this. The AK's don't seem to have any issues other than the weak disconnector spring I found  on the SAR3. I have bumped SAR1s and my Chinese  AK with no issues (they have the slower rate of fire also). I don't bump ARs that much any more because  I suspect it might break the firing pin and could possible fire out of battery which could be very dangerous.  
Mantra

I have 3 J&T kits that all bump just fine but I',ve done the 15min trigger job to all of them , I don't know if that made a dif or not .