7mmmountaineer
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Time to face it I am a workaholic............
Posts: 521 
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Post by 7mmmountaineer on Sept 9, 2014 8:06:50 GMT -5
Ok fellas I have a very weird situation. Since I am home and have some time on my hands I got up at the but crack to spend a few early morning hours at the bench. Took my 280 and my 308 out to tweak them this early am. I have a load worked up for both the 280 is shooting 150gr Sie Gk's with IMR7828 and the first three shot @100yds you could cover with a dime so I put it away and called it good. Broke out my 700 SPS Varmint in 308 and the first shot locked up my bolt. This was an established load of 45gr Varget and 165gr Sie GK's I have sent hundreds of these down range in the last year without a problem. Same lots on powder, primers, bullets and it is the 4th loading on this brass for this gun. Conditions were near perfect 65 degrees, no wind, humidity was in the 40% range, Barometric pressure was in the 29's and my bench sits at 3000ft above sea level. So this makes me wonder what could have caused this to happen? Why did it happen now out of the blue? I weighed and measured everything twice yet hear I am gun in the freezer for a few while I post rubber mallet ready to tap the bolt open. Guns were both cleaned yesterday so I can check that one off I am stumped looking for some reason this happened.
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dangun
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I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Sept 9, 2014 10:03:08 GMT -5
Chuck,
I would use a block of wood or a big dowel rod and whap the back of the bolt Like your driving it toward the chamber rather than on the bolt handle. Then try to open the action by hand. Those locking lugs can gawld the locking face of the receiver pretty bad if your not careful.
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on Sept 9, 2014 12:20:27 GMT -5
Dan the bolt came open easily with just a couple taps on the back of the bolt and a couple taps on the bolt handle after about 15 minutes in the freezer. Just because I was wondering I took the rifle back to the bench with the same loads from that batch and had no other issues fired 10 rounds once the rifle came back to room temp. I inspected the brass and measured it and it seem to be in spec. I haven't the slightest idea were to look as far as cause. I have used this load off and on for the last couple years in a couple different rifles including this one. The data is from Hodgdon's site I shot them an email asking if they had ever heard of this happening before. Their max charge is 46gr Varget under a 165gr bullet which I have also used in this gun but 45gr is the more accurate load.
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Sept 9, 2014 13:53:37 GMT -5
Chuck,
I'm glad all is well with your rifle. It could have been something as simple a a thread from a patch or a grain of powder stuck to the outside of the case or anything for that matter.
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bob
Member
I'm too old to be nice but never too old to learn!
Posts: 1,457
Location: Northern California
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Post by bob on Sept 9, 2014 14:40:27 GMT -5
This is interesting Chuck, I assume there are no marks on the case that would give it away. No noticable increaase in recoil or report either? Dan,that is a good tip driving the bolt foward instead of rearward as would seem propper. I do understand the reasoning. Thanks for posting this Chuck.
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on Sept 9, 2014 14:58:43 GMT -5
Case neck has a very small dimple on it just forward of the shoulder. HMMMMMMM I checked the barrel with my bore scope I didn't really look at the chamber.
Bob no nothing that I noticed at all and the rest fired just fine. |
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gws
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Posts: 969
Location: NW New Mexico
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Post by gws on Sept 9, 2014 21:43:49 GMT -5
Chuck, if that happened to me, and I was that sure of the powder charge and the primer type, I would measure and compare the case volume of all the rounds shot that day. If the stuck round has less volume, that might have caused it, especially if the bullets also have a variance one to another in weight. Smaller case volume combined with a slightly heavier bullet, in other words. Also manufacturers of bullets aren't always perfect in their quality control. A heavy bullet or two isn't that uncommon in a factory box, don't care who made them.
It actually did happen to me once a bunch a years ago, still not sure why, but I didn't know to measure case volume or bullet weight.
You can bet Dangun weighs each and every bullet he sends down the range in a competition.....and those bullets are the best he can buy.
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Sept 10, 2014 7:16:46 GMT -5
Yep each and every powder charge and every bullet and hours and hours of case prep.
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on Sept 10, 2014 9:41:06 GMT -5
GWS I don't usually sort my bullets by weight because I am only using them to hunt but after seeing this earlier this morning I took to my scale. This is what I found with the 143 bullets I have left weight range is 164.1-165.7 high to low. 80 of these are between 164.8 and 165.1, 44 are between 164.1 and 164.7 with 19 between 165.2 and 165.7. As for case volume all 50 pieces of brass in this cycle have a case volume between 48.6 and 49.0gr filled to the top of the case neck with Varget and a long drop tube sampled half the lot.
The one and only thing I can thing of is the last time I shot this rifle it was loaded with W748 and 150gr bullets. I may have had some stay behind under burnt powder I missed cleaning the rifle. Like I said earlier I didn't really check the chamber (stupid I know) with my scope. I will have to be even more careful with my scope inspections. I loaded another batch last night including the offending case weighed and measured every thing twice and grouped my bullets by weight. Will see how it goes later today I have to run out for a bit. |
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Sept 10, 2014 16:28:56 GMT -5
Chuck, That weight spread is not too bad for a factory bullet. I have seen much worse. In competition bullets it's huge and unacceptable. The bullets I buy or swage myself are +.1gr -.0. Those are grouped in lots of 50 The ogive is also measured and has a tolerance of +/- .0005" and the metplat is trimmed and re-pointed on every competition bullet I shoot. How's that for being anal retentive?  |
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on Sept 10, 2014 18:26:16 GMT -5
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Sept 10, 2014 23:04:43 GMT -5
You're a funny man Chuck
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on Sept 11, 2014 13:59:12 GMT -5
Dan what can I say I was runner up for class clown and least likely to see 25 in my high school class. Oh and voted least likely to give a FLYING FUCK what others thought of me...... |
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dangun
Member
I love the smell of burnt gun powder.
Posts: 517
Location: SW Florida
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Post by dangun on Sept 11, 2014 21:38:45 GMT -5
Well we certainly have the latter in common.  |
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bob
Member
I'm too old to be nice but never too old to learn!
Posts: 1,457
Location: Northern California
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Post by bob on Sept 11, 2014 23:28:37 GMT -5
Actually I think there are a few of us here that have that trait!  |
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7mmmountaineer
Member
Time to face it I am a workaholic............
Posts: 521
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Post by 7mmmountaineer on Sept 13, 2014 19:23:02 GMT -5
Actually I think there are a few of us here that have that trait! Bob I was told years ago my give a dam was broken I told my mom she was right and I wasn't gonna fix it either LOL............. |
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...... I didn't think that was to bad of a spread either but I had to know if GWS might have been correct. I still think that mabey I had some unburt powder in the chamber or mabey a little build up. I got the bore scope for my barrels and skipped right on by my chamber. DUH BIG RED TRUCK and yes I licked the windows on the short bus 
My daughter came from Missouri, my son and grand son, my wife and I had a nice dinner of grilled "porter house" pork chops, corn on the cobb, my son, G'son and I share 10/5. G'son is 4 minutes early though @ 10/4.
Pooh I hope you find to right house . 
