New 6x47 Lapua build issues

[jwcrabb]

Guys,
I just got my new 6x47 Lapua build finished. I started working on load testing and i'm having misfires. The first five shots were fine, but then it misfired 3 of the next five. The primers on the misfired rounds appear to be hit plenty hard, exactly the same as the fired rounds. I disassembled the bolt and checked and cleaned the firing pin assembly, no issues I could see. My next thought was maybe bad primers?? I'm using CCI 450's. I loaded up another set and used a different primer(Federal small rifle match). Still had a few misfires. My only guess now is maybe a bad batch of powder?? I'm loading Varget that I have had around for several years. I picked up a new can this morning and will try that. Any ideas??

 

[ShootDots]

I would bet that if you are using NEW (virgin) brass that you sized down to 6mm, that the shoulders are WAY back of "normal".. I had a batch of 6.5 x 47 brass I necked down to 6mm and put my competition load in it and went to a 600 yard match. I had enough misfires that I almost could not finish the match>> I got exactly 60 shots in.. At any rate, the shoulders on the "misfired" rounds were anywhere from 14-16K SHORTER than a fired round.. I took the misfired brass and reseated the bullets WAY out and jammed them in>> VOILA!! They all fired.. After fireforming, all such problems evaporated..

 

[jwcrabb]

This is new 6.5x47 Lapua brass that I resized to 6mm. If your theory is correct, would everything be ok after they are fired one time and then resized? On the cases that misfired, I just pulled the bullet, resized, reprimed and reloaded. Will these cases misfire again? I guess what i'm asking is if full length resizing does anything to fix the issue, or must they be fired to correct? What does seating the bullet way out into the lands do to make it fire? Thanks

 

[ShootDots]

Seat those bullets out to a hard jam>>>Then they will fire... After ALL are fired, your normal F/L sizing will be as it should.. have no worries... The reason you want to seat those bullets out is to HOLD THE CASE HEAD AGAINST THE BOLTFACE, thereby allowing the firing pin to really upset the primer, causing it to fire..

 

[jwcrabb]

Ok Guys, I think I get it now. If they misfire again i'll jam the bullets. I also remember that some of the loaded rounds chamber noticeably easier than the others. Could this be the ones with the shorter shoulders? I never paid attention before.

 

[ShootDots]

Can you pull the bullets out some and reseat long? If not, and they misfire again, there will be NO DOUBT that the theory we are working off of is correct. However, I hope that they ALL fire.. When the bolt closes like there is nothing in the chamber, it's because the bolt has NO resistance coming from the case>>>it is as if there is nothing in the chamber as far as the bolt is concerned. That is due to a really short case..

 

[Quickoz]

Jw, dont try again like normal. Just jam then about 30 thou with about 2 thou nk tension and fire them or it will probably misfire again.

 

[bheadboy]

Take the fired cases, compare to the unfired cases the case head to shoulder length. if it is shorter, use an impact bullet puller to ease the loaded bullets out .02-030" then jam and shoot.

Bob

 

[Changeling]

Did you contaminate the primers in some way?

 

[delivery_boy]

Just something else to think about, are the primers seated deep enough? I had a similar issue with my 6BR. I hadn't seated the primers deep enough to hit the base of the pocked. Struck primers were jumping forward upon the strike without if nightlong. I gave them 2-3 clicks in my 21st century timing tool and reseated them and they all fired second time around

Delivery_boy

 

[Southernfairy]

Guys,
I just got my new 6x47 Lapua build finished. I started working on load testing and i'm having misfires. The first five shots were fine, but then it misfired 3 of the next five. The primers on the misfired rounds appear to be hit plenty hard, exactly the same as the fired rounds. I disassembled the bolt and checked and cleaned the firing pin assembly, no issues I could see. My next thought was maybe bad primers?? I'm using CCI 450's. I loaded up another set and used a different primer(Federal small rifle match). Still had a few misfires. My only guess now is maybe a bad batch of powder?? I'm loading Varget that I have had around for several years. I picked up a new can this morning and will try that. Any ideas??

I had this exact issue with my 6x47 build over here in the UK. My issue was due to my firing pin spring being of the wrong spec. Lovely light bolt lift but it turned out it didn't have the oomph to reliably ignite the primers every time. I had a similar frequency of misfires to you so if you don't resolve this issue by jamming might be worth looking at your spring?

 

[basshusker]

+1 on what shoot dots said. Had exact same issue. Wish I had that info when I started because I was going nuts.

 

[Erik Cortina]

Another note on what ShootDots said. Too much headspace will give you misfires, but excessive headspace will pierce primers.

Reduce powder charge, jam bullets hard into the lands, and shoot the problem cases. After the first firing, bump the shoulders a minimum amount (if needed) and they will no longer be an issue.

 

[lpreddick]

a headspace gauge will tell you which cases aren't going to contact the end of the chamber. i will fireform these with pistol powder and cow, then load.