My gun has just started putting the first two rounds high after 1200 rounds on the tube. At 300 yards today the first two shots would touch then drop 1 moa and the rest of the shots would still group 1/4 moa directly beneath the first two. I had 3 strings of 8 loaded to practice and it did it each time. What could be the cause?
1st shots high
- Thread starter jsthntn247
- Start date
I'm not sure but one rifle and load I had started going crazy when I used the same powder but changed lot number and then about the same time found out the throat was getting longer. I changed to different powder and speed and now my rifle is shooting good again. Just a thought here as I am no expert. 
watercam said:
308, 4350 215 Bergers slightly compressed, f/tr, Bartlein, stainless.
Assuming this happens with a cold, fouled barrel it sounds like a similar issue I was having with carbon ring build up ahead of the throat. I thought the barrel was toast until I poked a bore scope in there and saw about 4" of hard carbon when I thought it should have been clean. Took some effort but got it out and the barrel came back to life.
Yes, it happens with a cold fouled barrel. I'll have to have it bores scoped and see. It's been doing it the last 150 rounds or so.
Joe R
Gold $$ Contributor
Finding a gunsmith with a bore scope was a challenge for me. I resorted to buying my own digital bore scope.
I bought one like this http://www.amazon.com/Removeable-Megapixels-interface-Inspection-Borescope/dp/B00FALVTRM/ref=sr_1_6?ie=UTF8&qid=1402868854&sr=8-6&keywords=5.5mm+digital+borescope and I feel it was money well spent. Like the old saying goes "seeing is believing" Once you start looking in there it will likely change your whole cleaning assumptions.
I bought one like this http://www.amazon.com/Removeable-Megapixels-interface-Inspection-Borescope/dp/B00FALVTRM/ref=sr_1_6?ie=UTF8&qid=1402868854&sr=8-6&keywords=5.5mm+digital+borescope and I feel it was money well spent. Like the old saying goes "seeing is believing" Once you start looking in there it will likely change your whole cleaning assumptions.
What did you have to use to get it out?
Joe R
Gold $$ Contributor
Right after I finish shooting, while the barrell is still hot I squirt brake cleaner down the neck. You can get a can at Walmart for $3 will last you months. I also use this brush, I dip it in bore cleaner rotate it several times in the throat, I let it soak while I run the wet bore brush. I let soak for about five minutes and then clean everything. The bore scope tells the tale. Every couple hundred rounds I use JB Bore paste remove all the copper while it polishes the bore. I also give a final coat of Kroil, that makes cleaning much easier next time around.
The kroil is a penetrating oil, it penetrates steel and skin, so use gloves unless you want to hurt you kidneys and liver. That way when you fire your first shot it's not going down a dry bore.
The kroil is a penetrating oil, it penetrates steel and skin, so use gloves unless you want to hurt you kidneys and liver. That way when you fire your first shot it's not going down a dry bore.
Attachments
Joe R
Gold $$ Contributor
That is a very good question. I don't know what "cracking" looks like and I haven't really looked for cracking in the lands, but since I have two new custom rifles and a well used Savage 308 I'm going to take a look in the next couple of days and see what I can see.
When you say "cracking" I assume you mean very tiny hairline cracks, right?
The reason I bought it, it was economical and not fragile like the Hawkeye. I just was looking for copper build up, carbon ring and such. It has worked really well for that. The cracking issue may be a challenge for it since it has a some magnification ability (4x I believe) but I don't know if that is sufficient. I know some of the digital microscope go to 80x. You can get one for around $30. When I have time, in the next couple of days I will check and report back.
Joe
watercam said:
I had no measurable throat erosion after until 750 rounds. After that point, my throat has been moving back .005-.010 each 100 shots. Should this have been a sign that the throat had begun to get pitted and powder fouled and therefore needed jb bore paste or somehting to smooth it out? It would seem a pitted, carbon laden thorat would erode more rapidly because the blast from the next shots would have more to act upon and blow away???
Joe R
Gold $$ Contributor
jsthntn247,
You're opening a can of worms regarding carbon, barrel life and throat erosion.
Joe Hendrick's paper on the 6CM thought me the importance of slow burning powder and barrel polishing routine to extend barrel life way beyond accepted norms. He talks to the 6CM (Competition Match) caliber, but clearly that methodology is applicable to any caliber or rifle. Some people that have been using the methodology report superb results, I believe them, but I haven't verified those claims. I'm just starting down that road with a new customs 308 and a 6CM rifles. Won't know the answer for a couple of years.
I've gone another step further by looking to remove as much carbon as possible from my brass and rifle to extend barrel life. My reasoning is that any carbon left inside the brass from the cleaning process gets blasted to the back of the bullet and the barrel. We all know that carbon is one of the hardest substances on the planet, with enough pressure it becomes diamonds. If sandblasting is harmful I reason that carbon blasting at 50,000 psi is not good for your barrel or the stability your bullet. Granted it is a very minute quantity.
So, in my search for cleaner inside brass I've ended up with a tumbler and stainless steel pins as a way to get the brass clean. After playing with my new tumbler for 3 weeks I've finally arrived at a process that turns my 4x fired brass into something that is indistinguishable from virgin brass. Getting the carbon out, I believe can only help accuracy and barrel life, it certainly doesn't hurt it.
jsthntn247, I don't know if I've answered your question, but I've given you my perspective, I'm not an engineer, so take what I'm saying with a grain of salt, YMMV. Read Joe Hendrick's paper below, its very interesting.
Kindest regards,
Joe
You're opening a can of worms regarding carbon, barrel life and throat erosion.
Joe Hendrick's paper on the 6CM thought me the importance of slow burning powder and barrel polishing routine to extend barrel life way beyond accepted norms. He talks to the 6CM (Competition Match) caliber, but clearly that methodology is applicable to any caliber or rifle. Some people that have been using the methodology report superb results, I believe them, but I haven't verified those claims. I'm just starting down that road with a new customs 308 and a 6CM rifles. Won't know the answer for a couple of years.
I've gone another step further by looking to remove as much carbon as possible from my brass and rifle to extend barrel life. My reasoning is that any carbon left inside the brass from the cleaning process gets blasted to the back of the bullet and the barrel. We all know that carbon is one of the hardest substances on the planet, with enough pressure it becomes diamonds. If sandblasting is harmful I reason that carbon blasting at 50,000 psi is not good for your barrel or the stability your bullet. Granted it is a very minute quantity.
So, in my search for cleaner inside brass I've ended up with a tumbler and stainless steel pins as a way to get the brass clean. After playing with my new tumbler for 3 weeks I've finally arrived at a process that turns my 4x fired brass into something that is indistinguishable from virgin brass. Getting the carbon out, I believe can only help accuracy and barrel life, it certainly doesn't hurt it.
jsthntn247, I don't know if I've answered your question, but I've given you my perspective, I'm not an engineer, so take what I'm saying with a grain of salt, YMMV. Read Joe Hendrick's paper below, its very interesting.
Kindest regards,
Joe
Well, I might have found the reason why it starting doing this all of a sudden. I removed the scope several weeks back to have some stock works done. While talking to the fella about pinned bases and their removal we popped the base off and put it back on. I forgot about that and never checked the screw torque before putting the scope back on when picking the gun up. None of the screws had any torque on them. Man let me tell you, that mistake has cost me allot of headache. I have no idea how it's even shot as well as it has been.
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