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A real puzle for someone...I can't figure it out...yet.


jakfrost1

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13 minutes ago, Shmella said:

I’m going to say it’s a gun issue. Not a mag issue. As pointed out by waco in the other thread probably something to do with the barrel lock up. He shoots a lot and tinkers a lot with open guns. I trust his word on a lot of issues. 

 

I’m wandering down that road also Shmella, not sure exactly how its a gun issue yet, but so far that seems like the most likely suspect in this mystery. 

More testing required, but my squad time is 0900 tomorrow, 2hrs away...so guess I’ll have to take the ‘1st shot C’, and nail all the rest, haha. 

Testing will resume ASAP after the match. This isn’t likely to be solved easily...

Edited by jakfrost1
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3 hours ago, jakfrost1 said:

 

 did Massad have any explanation for his theory?

2 hours ago, 9146gt said:

Same thing happens with the  1st shot from a Ransom Rest

1 hour ago, superdude said:

 

I see this when shooting from a Ransom Rest with some guns. That's why many Ransom Rest shooters shoot the first round off target, and the remaining ones for the group. 

 

 

Massad never explained it (not sure anyone can), but if it happens with a Ransom Rest,

I believe it does happen.     

 

So, if going for groups, I fire the 1st shot into the berm    :) 

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7 hours ago, jakfrost1 said:

 

Well I might give that thought some consideration except for the fact that in this case, if anything, the opposite would be true. Because...I am using MBX 155mm mags which without being restricted to 10 + 1/2 rounds by a ‘follower stop’ would hold 27 rounds. So the 13 coil spring is not even half way compressed. 

But what the heck, at this point I’m quite happy to try any suggestions!! 

 

If your MBX mags are new, or the springs are new, that is part of your problem.  New MBX springs are waaaay too tight and push the round up hard.  MBX recommends you condition the new springs by leaving the mag fully loaded for at least a week.  I've found two weeks is required to settle the springs and feed right.

 

Some people suggest cutting one coil off the bottom.  A 13 coil spring is right for 170 mags, but a little long for a 155.

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As we've been through before, sometimes this just happens. Experienced it with multiple guns. I won't speculate on all the reasons, but somehow the in-battery condition is just different between a hand chambered round and one chambered violently from firing. 

 

You can try smartly racking the slide to Barney up from a mag holding only one round and see if that'll help for the match. 

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1 hour ago, zzt said:

 

If your MBX mags are new, or the springs are new, that is part of your problem.  New MBX springs are waaaay too tight and push the round up hard.  MBX recommends you condition the new springs by leaving the mag fully loaded for at least a week.  I've found two weeks is required to settle the springs and feed right.

 

Some people suggest cutting one coil off the bottom.  A 13 coil spring is right for 170 mags, but a little long for a 155.

 

You are absolutly correct, zzt. I bought new spring/follower kits for all 6 mags and after installing them I was suddenly having feed problems. Put the old ones back in ( they were working fine, just figured after a year or so maybe some preventive maintaince) and all is good again. Guess I’ll have to ‘season’ the new ones this winter...

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I know of a buddy who had a problem with a tight fitting barrel and lock up and his did some wierd stuff on that first round when not "slammed" by the cycling of a round fired.

Edited by TRPOperator
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Have you tried a single round in each mag?  Load first 1 like normal & shoot.  Chamber is empty, insert new mag 1 round only, chamber it & shoot.  Repeat for several mags.  Report results....

My curiosity is picqued.

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On 7/29/2018 at 2:39 AM, Hammer002 said:

Well, I for one learned something today.  Never thought about the first round being different, but makes perfect sense in how the lugs would lock up differently.  Interesting...

 

I'm not sure how it makes perfect sense.  In fact, seems to me to not make sense at all.  As for first round variations in ransom rest, as far as I've seen that is always due to setup and not some magical variance in the pistol.  That's assuming a custom gun with all parts fit properly.  Typically how this goes is the rest gets setup and all appears to be good to go, but the rest isn't 100% secure.  So the first round is fired and the rest is then seated in place and subsequent rounds group consistently.  Maybe there's some voodoo magic involved, but I've yet to see an explanation for how this can happen from a mechanical standpoint.  If anyone wants to explain, I'd be very happy to know.  

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ransom rest hold securely only the grip of the gun. all 2011 platform has some flex . too much pressure  with full mag will  force hit first round down .

if u will aim thru sights  u will find that gun shoot better group  and first round will hit exactly in same place. 

check this with red dot scope mounted on slide and i will find that this" issue" not exist. 

Edited by yigal
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2 hours ago, ltdmstr said:

 

I'm not sure how it makes perfect sense.  In fact, seems to me to not make sense at all.  As for first round variations in ransom rest, as far as I've seen that is always due to setup and not some magical variance in the pistol.  That's assuming a custom gun with all parts fit properly.  Typically how this goes is the rest gets setup and all appears to be good to go, but the rest isn't 100% secure.  So the first round is fired and the rest is then seated in place and subsequent rounds group consistently.  Maybe there's some voodoo magic involved, but I've yet to see an explanation for how this can happen from a mechanical standpoint.  If anyone wants to explain, I'd be very happy to know.  

 

Thank you for including me in your angry little world.  How about engaging the root/source of the idea I was commenting on in a positive way as it was a new idea to me, huh?

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On 7/27/2018 at 10:39 PM, Sarge said:

In my guns it doesn’t seem to matter enough for me to tell. By from what I understand tight fitting guns can have a different POI on first rounds fired.

Depending on how tight your chamber is could keep a round out of normal battery battery by a fraction of a mm. This could cause a shift and slight tumble out of the barrel. Did you get any keyhole shots that day

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I have the same problem and the only thing that helps is a firm grip on the gun while loading the first round.

the gun has to much headspace (my fault, don't build your first gun with a trubor barrel) but the problem started after a few thousand rounds. I always shot 115gr bullets and they don't group well anymore, only 124gr.

 

the comp doesn't hit the slide, without the extractor the problem still exist, aimpoint micro or cmore railway makes no difference, 10 or 8lbs recoilspring does not affect the problem, reamed out the comp...

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