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Posted: 12/5/2010 3:24:24 PM EDT
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Rifle and mag are new, about 200 rounds down the Tube.
This was my second range day, first time out no issues at all. Today this happened twice. Also three times on after the last round, the bolt did not lock all the way back. Locked about 1/2" short of all the way back 
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Need information on the rifle, but you have a short stroking problem, with the bolt not coming back far enough to allow the mag time to recover, and the bolt is driving the top round out of the mag via the middle of the case, and not from behind the rim.
To be brutal honest, unless something major happened the the rifle, this problem is screaming of a lack of proper cleaning and lubing. From just looking at the action, I can tell you that you are not CLP lubing the upper bearing areas enough for break in, and would dare to guess that you are using something like Hoppes to clean the barrel and leaving remnants of the Hoppes behind to mix with the lube that you may be using, which is causing a sticky mess, and causing the problem in itself. So visit the cleaning forum to get an idea how and what to use to both clean the rifle (including a chamber brush) and what/where to use to lube the rifle as well. If, once the rifle (and mags) are correctly cleaned and CLP lubed, you are still have problems, then we can go over the finer details. |
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Quoted:
Need information on the rifle, but you have a short stroking problem, with the bolt not coming back far enough to allow the mag time to recover, and the bolt is driving the top round out of the mag via the middle of the case, and not from behind the rim. To be brutal honest, unless something major happened the the rifle, this problem is screaming of a lack of proper cleaning and lubing. From just looking at the action, I can tell you that you are not CLP lubing the upper bearing areas enough for break in, and would dare to guess that you are using something like Hoppes to clean the barrel and leaving remnants of the Hoppes behind to mix with the lube that you may be using, which is causing a sticky mess, and causing the problem in itself. So visit the cleaning forum to get an idea how and what to use to both clean the rifle (including a chamber brush) and what/where to use to lube the rifle as well. If, once the rifle (and mags) are correctly cleaned and CLP lubed, you are still have problems, then we can go over the finer details. Thanks for the input. Rifle is brand new, Rifle has been cleaned properly and thoroughly lubed with CLP only, no Hoppes or the likes. Chamber has been polished with Flitz. First time out I did lube the bolt and Upper with Tetra gun grease and had zero issues. This time I only used CLP and cleaned after every 10 rounds including the Chamber, then relubed with CLP. However I did not lube the Chamber, only cleaned with Milspec Solvent and then wiped dry with a clean dry patch. Other than a dry Chamber, anything else that may cause Short stroking ? |
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Chamber brush the chamber with CLP by hand, the patch it dry.
On the B/C, CLP coat it heavy inside and out, then give it a flick to know off the excess CLP, put it into the upper, and empty charge the upper a few times to make sure that the CLP has migrated to the bearing surfaces. Now on the rifle, I can see that the upper at one time was ejecting fine by the marks on the defector, so what has changed besides just cleaning it? Has the key come loose from the carrier (bolt not longer at 37in lbs), did you get a round nose up jam, and now the gas tube is not longer aligned with the carrier key, or has the gas block come loose on the barrel, and it leaking there. Did you blow a primer, and have a piece of it wedged in the carrier key? Mags, could be a problem, but if you pulled them apart and cleaned them, then they should be as good as there where the first time out. Lastly ammo, Is this the same ammo as last time, or did you change ammo? We need details on the rifle (brand/type) and what has changed since the last time it was running fine. |
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Quoted:
Chamber brush the chamber with CLP by hand, the patch it dry. Done On the B/C, CLP coat it heavy inside and out, then give it a flick to know off the excess CLP, put it into the upper, and empty charge the upper a few times to make sure that the CLP has migrated to the bearing surfaces. Done Now on the rifle, I can see that the upper at one time was ejecting fine by the marks on the defector, so what has changed besides just cleaning it? Nothing Has the key come loose from the carrier (bolt not longer at 37in lbs), did you get a round nose up jam, and now the gas tube is not longer aligned with the carrier key, or has the gas block come loose on the barrel, and it leaking there. Did you blow a primer, and have a piece of it wedged in the carrier key? Key is tight Gas tube fine gas block and no leaks No blown primers or other obstructions Mags, could be a problem, but if you pulled them apart and cleaned them, then they should be as good as there where the first time out. Brand new CPoducts mag Lastly ammo, Is this the same ammo as last time, or did you change ammo? Both times my handloads, first time was using Varget, this time H-335, this time the rounds are stouter, not hot loads just stouter than with the Varget, Same bullets Hornady 55gr. SP probably running about 3100fps We need details on the rifle (brand/type) and what has changed since the last time it was running fine. RRA Predator Pursuit Upper with Chrome BCG Tactical Machine lower RRA NM 2 Stage LPK RRA A2 Butt stock assembly I just finished going through it, no visible defects anywhere. Got alot of powder residue out of the BCG, used brake cleaner to blow it out, then compressed air to dry it, then soaked it with CLP and blew off the excess, wiped the upper down with CLP Only thing different this time out, was the first time out I lubed the bearing surfaces with Tetra Gun Grease 
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Need to see the spent primers on the H-335 ammo.
The Varget is a slower burning powder, so it will create more gas port pressure (dwell time of the burn), and am trying to figure out if you are over the top of working pressure, or way under and the reason for the short stroke with that powder. Also, load a mag of Varget ammo as well for testing (but make sure that you have correctly trimmed the cases, and full sized them as well). It the H-335 is in the correct pressure range, could be that the barrel gas port is too small for standard burning powders. And, leave the B/C on the wetter side for rifle break in (again, a quick shake, not blowing all the CLP off it before it's put into the upper, so yes, you are going to be running the upper on the CLP wetter side). If the rig runs for a while, then starts to choke, pull the B/C and relube it again (again on the wetter side since CLP has a cleaner in it, and will start to clean the parts while you are shooting the rifle). |
I forgot I was shooting one other load, and now I am not sure which load it was Short Stroking on 
The other load: 55gr. SP 25.0 and 25.5 of TAC This load had very soft recoil. These are Pics of the spent cases from the H-335 loads. 55gr. SP 24.5gr. and 24.8gr. of H-335 GM205M Primer 
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On the H-335, the primers do not show signs of over pressure, but am seeing some strange marks on the side of the cases either screaming dirty chamber or over pressure pull marks from the chamber.
http://data.hodgdon.com/main_menu.asp 55 GR. SPR SP Hodgdon H335 .224" 2.200" 23.0 3018 40,800 CUP 25.3 3203 49,300 CUP So with that in mind, bump the charge with max still, and see if the problem gets worse, or better. ON the TAC, it shows a max charge of 26, so you could bump the charge a tad amount as well for testing. http://www.ramshot.com/powders/ TAC 55 SIE BK 23.4 2,966 26.0 3,295 54,881 2.240 And go back and retest the rifle with the varget loads again for good messure to confrim that something has not changed on the rifle, and you are chasing your tail with the loads). With all the above load, you should well in the hunt, and got a feeling that there is either some major binding going on, or the gas system has a leak that you have not found yet (read are you sure that the gas block passage in indexed on the barrel gas port, did not get semi clogged, and is still tight to the barrel? Same thing for the carrier key to the carrier as well) |
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Well I went to the range today.
No Feeding issues, Functioned 100%, but I could not get the rifle to shoot any consistant groups and grouping was always over 1" Ammo used: Federal 55 FMJ Varget, 55SP Varget, 55 V-Max Varget, 40 V-Max H-335, 55SP H-335, 40 V-Max TAC, 55SP These are all loads that shoot well under MOA in any rifle I have used them in, including two other RRA Uppers. |
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Guessing that the round count is now around the 500 mark, and if so, you can start backing off on the CLP (telfon in the barrel bore can reek havoc on groupings until it burns off).
On the barrel, go with something like sweets copper solvernt to make sure that you have removed all the copper gilding (read sweets will do the work for you, so you don't have to do a lot of scrubbing). On the barrel, need to figure out the jump with the rounds loaded from the mag, and even some sled rounds that you can long load as well. In regards to long throat jumps (+.010) your going to find that flat tail bullets will do better than bolt tail bullets, expecily when you are only printing out at say 100 yards. When you can long load and have a short jump (.003), the break out the boat tail bullets. Also, you need to play with the loads not only for then to sleep before reaching the target, but to find the sweet harmonic spot of the barrel exist. Hence, when a round is sent down a barrel, the muzzle is going to start to do a oblong circle movement, and it's at one either of the two end points that you want the bullet to exit since muzzle will be at it's stilliest. If you have the bullet exiting during the long stroke between the two, and throw in high devation of FPS per round, then it in it's self will open up the groupings. So clean the barrel, make sure that the barrel nut is tight, and start playing with loads. The barrel has just about seasoned, and should be able to come up with some tack driving loads. And no, what may work in one rifle, does not always mean that it will work in another. Jump to lands, barrel harmonic, and even if the rig is clean loading the round (bullet not bent in the case) come into play here. |
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