Modern Sporting Rifle Evolution
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RedRaider

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Reply with quote  #1 
I finally got to shot my 20" Goose yesterday and love it, but I had FTF and some FTE.
Only have my wolvie lower with me and its a carbine buffer. I believe this may be part of the problem. Is anyone shooting a rifle length bbl w/carbine lower setup?  Took the gas block off and port is lined up correctly, think the bolt is outrunning the mag.  The  FTE started the higher the charge.  The brass would get caught in the ejection port.  Fired 60 rounds all FTFed. 
used  blc2 w/55gr shots started @27.5-30.5gr    Best gruop{3} 30gr  .3075" 100yds
          blc2 w/70VG      28.0-29.5                                              

         1200R   55 shots   24.5-27.5                        Best group{3}  25gr  .365" 100yds
                       70VG       24.5-26.0

Only powders i have with me here in TX/NM are 1200R,Blc2,Blkout,1680.
Have 322,335,414,LeveR,3031 but they are back in MS, no good to me out here!!
Guess I need to find a local powder supplier to get this beast running.  no chrono with me at this time so no vel. data.  Was just trying to see where pressure signs show up with these combos.. Can you put a rifle buffer in a carbine tube?  Forgot to state I have a m16 style BCG. Other options? 
Now,  I'm a proud member of the Jal, NM Gun Club.  Love small towns where you can have a place to go shot for a $20/yr membership, worth every penny when your away from HOME!!!

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BIGGDAWG

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Reply with quote  #2 
no you can't put a rifle buffer in a carbine tube but you can go to an h2 or h3 buffer. or you can get some tungsten buffer weights and just add to your current buffer.

so your having fail to feed issues and fail to eject?  which probably means the fail to eject is causing the fail to feed?

something to check is take the bcg out and push a case into the bolt and see how the extractor grabs the rim.  it may be too tight or too loose and not hanging on to the case long enough or too long.

if it was feeding and ejecting with the lower charges but not the higher charges you could be correct and it is over running the buffer. adding weights to the buffer or going to an h2 or h3 will help with that. you could also just add an adjustable gas block and turn the gas down a little.

i have not run blc2 but it should have plenty of gas and run good with the charges you listed.

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RedRaider

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Reply with quote  #3 
Thanks Biggdawg
I do have an adjustable GB(didnt think i needed one on a rifle)will give that a try and see if if works, will be building a rifle lower for this, but i was itching to shoot it.  from the way it was hanging the brass in the ejection port i believe the bcg was catching it before it cleared and the fact it was ejecting at lower charges just not feeding. charge went up- bcg speed went up also causing the problem.  Lower charges were ejecting around 5o'clock
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BIGGDAWG

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Reply with quote  #4 
i have not had an adjustable on mine and you shouldn't need it but you can use it to test the theory of carrier speed because you can slow it down with it.  if you have another bolt it wouldn't hurt to try it too just to see.
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RedRaider

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Reply with quote  #5 
I have 2 others with me but all of them are full BCGs.  Im trying GB first.
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RIGGS68

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Reply with quote  #6 
I too had issues my first outing with my Mongoose. I believe mine was due to a combination of the donut on the brass, the Pmag I brought along, and the fact that the build was a little "stiff". I thoroughly cleaned and lubed the rifle, grabbed an assortment of magazines and returned to the range (after loading some hotter rounds in my newly fire-formed brass as well) I did not experience any problems during the second range trip unless I used my older Pmags with newly formed brass. I did remove my catcher during the first outing and, like you, found my brass to be ejecting @ 5:00. This problem was gone after the cleaning and lube session. I have M3s that I ground down the over-insertion stop (billet lower) that fed the fresh brass flawlessly on the second trip. BTW- mine is a 20" rifle gas with a standard weight carbine tube/buffer.

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RedRaider

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Reply with quote  #7 
If all goes well, I'm headed to the range this afternoon.  Will update my progress. 
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RedRaider

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Reply with quote  #8 
Made it to the range and I still have issues. Adjusted GB all the way down so it would not eject. Shot rounds and opened it as I went. Rounds would eject but FTF(feed). Tried 3 different BCGs and mags. It shot great just doesn't function correctly. I loaded 6 pcs of FF brass still didn't help. Now what? Here is a couple of photos of a group and a view of the range

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BIGGDAWG

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Reply with quote  #9 
can you tell me how they are failing to feed?  is the carrier picking up the round and it is hitting the feed lips? hitting the breach of the barrel?

is it missing the round and not picking it up?

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kf4zht

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Reply with quote  #10 
Watching this. I had issues with mine FTF. Bolt was failing to strip another round out of the mag. Tried 20rnd steel and pmags, both had the issue. I am thinking it may be due to the 55gn shots bullets being so short they are moving forward in the magazine. Plus these were fireform rounds so the cases weren't perfect. 
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RedRaider

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Reply with quote  #11 
With virgin brass it does not try to pick up the next round. With ff brass it would strip the next round but only feed it past the shoulder. Used a 20rnd gi mag,10rnd pmag,and bushmaster 10 with the same results.
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BIGGDAWG

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Reply with quote  #12 
if it is not picking up the round at all  you have to figure that out first.

take and load a mag, make sure it is on safe and try and cycle a mag with the charge handle if it won't cycle you have to see if the rounds are sticking up high enough for the bolt to catch them.

if they will cycle by hand then you have to figure out if your bolt is going back far enough to pick the round up. load one round fire it if the bolt locks back open the gas block a half turn and load 2 rounds see if it will cycle 2 rounds. 

if you can take a video of the ejection port when firing i may be able to help more..

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RedRaider

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Reply with quote  #13 
Adjusted gb from closed no bolt movement then half turn fire 1/2 turn to wide open. I had zero fte after 1-1/2-2 turns. After I opened gb enough to eject -- all were ftf. Will try a mag by hand when I get home

Firing one shot at a time bolt will not hold open
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BIGGDAWG

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Reply with quote  #14 
if bolt will not hold open then you have some sort of gas issue. not enough the way it sounds. you need to run a powder bullet combo we know works get it running then do load development


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RedRaider

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Reply with quote  #15 
Here is a pic of the gas port after 1st 60 rnds. Will take another later to night

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RedRaider

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Reply with quote  #16 
Looks the same only darker. Manually working the bolt - gun feeds and ejects both 55 gr shots and 70 gr VG
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BIGGDAWG

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Reply with quote  #17 
you don't have enough gas, you can open up the gas block all the way. 

take and load blc2 with the 55 shots at 31 grains that should be a 45kpsi load  there are better powders like h335 but that load should be enough to cycle the gun. 

1200r is plenty fast and takes more port than the mongoose was designed for. if you want to run 1200r you will have to open the gas port up.

i will load the same charge and see how my gun runs on it.


your gas port should be an .088 so that needs to be checked. if you want to run 1200r it will probably need to be .093 to .096 is my guess.

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RedRaider

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Reply with quote  #18 
I had primers (wolf)flat and flowing a little with 30.5 gr blc2/55shots. I will try 31grs. I just don't see how I'm undergased if I'm getting flat/flowing primers. I'm not an expert that is why I ask and yes I've been wrong before. Also that is the only powders I have with me in the middle of nowhere New Mexico. Just trying to make it work with what I have and it may not work!
Thanks again for all the advice.

Is there any loads I could try with 1680 or blkout-- I know they are faster but could I load some light charges to get enough gas to see if it will cycle?
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MDWS

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Reply with quote  #19 
I can run 1200R and 70TNT but I don't think I've run lighter bullets with it. I'll look and see.


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BIGGDAWG

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Reply with quote  #20 
Quote:
Originally Posted by RedRaider
I had primers (wolf)flat and flowing a little with 30.5 gr blc2/55shots. I will try 31grs. I just don't see how I'm undergased if I'm getting flat/flowing primers. I'm not an expert that is why I ask and yes I've been wrong before. Also that is the only powders I have with me in the middle of nowhere New Mexico. Just trying to make it work with what I have and it may not work! Thanks again for all the advice. Is there any loads I could try with 1680 or blkout-- I know they are faster but could I load some light charges to get enough gas to see if it will cycle?


if your primers were flat and cratered then don't load higher. i am going by quick load data and it isn't always right. 

as far as black out and 1680 they will only make your problem worse. it would be easier to get them to run on 1200r. the faster the powder the less gas so with a given port size if you go faster powder you need more port.  the mongoose uses the same basic powders as the 223 and that is what it is ported for.  if you want to get it to run with 1200r we can no problem open the port up then when you decide to use the slower powders then it will be over gassed and will need an adjustable gas block.

blc2 is the powder you have that should cycle the action. i need you to take a fresh case put a spent primer in and check your case capacity i can dial your load in better. but even 30.5 grains should be about enough to cycle it.

flat primers and flowing with fresh cases can also be a sign of excessive head space.

try and get me case capacity of water, and if you have some of the cases fired at 30.5 blc2 and the 55 a picture of the primer will help also.

you state you can't believe it is a gas problem but you can cycle them by hand number 1 number 2 they don't lock back on last round so the carrier isn't moving back far enough to lock back. you can also try a lighter buffer if you are using an h buffer go back to a standard.

this is why i said to totally rule out gas you need to load a known load and 28 grains of h335 with the 55 shots and fresh cases runs fine in many guns for fire form loads.



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wikster1983

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Reply with quote  #21 
Are these fire forming loads? I'm trying to duplicate your results with my 20" and that powder fills un-fired brass to almost top of case. (in my brass- Rem virgin)

Not being a smartass but are you sure your gb is opening up? not that there is something obstructing tube or port between tube and gb?

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wikster1983

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Reply with quote  #22 
Loaded up 3 with 30.5 blc-(2) 55gr. shots, rem un-fired brass, s&b primers- all ejected, fed, and showed zero pressure signs. fireformed nicely. Locked back on last round, as well.
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RedRaider

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Reply with quote  #23 
Going to see the man that is over the range this afternoon, he reloads and I will see if he has any powder I can buy/ use that will work. 335 322 benchmark maybe 8208. If I'm lucky. What I meant by gas problem is- with flat primers there should have been more than a enough gas to cycle. No pics of primers in cases b/c I resized them a few hours ago but have primers. Not the best pics but I think you can see enough.

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RedRaider

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Reply with quote  #24 
I was using blc2 bc it works w/ 6x45 and 223 so I knew it should work w/mongoose

Wikster. Have taken off 3 times now. Physical looked in the hole and opened all the way. While shooting it the other day I almost back it out too far was leaking gas around adjustment screw.
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wikster1983

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Reply with quote  #25 
Can you blow through the gas tube into the gb when off the barrel? You should have more than enough gas if its getting through gas block and tube.
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