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Old October 1, 2013, 12:50 AM   #1
Metal god
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Cleaned bore,chamber and throat to bare metal . Seating depth changed ALOT

I put this in my WCC brass thread but It's way off topic so I started a new thread for this issue .

Quick back story for those who do not know my bullet seating issues I was having . When I first started loading for this rifle ( 308 Savage ) if I loaded the round ( 175gr SMK or 178gr A-Max ) to an OAL of 2.800 I could not close the bolt and if I foced the bolt closed It was very hard to extract the round to the point of have to use a malet on the bolt . The SMK had to be 2.730 and the A-Max had to be 2.750 and that put them both right at the lands or so I thought .

Now that I cleaned my bore to bare metal . It now appears one or two things has happened . either the copper and fouling build up was so great . The fouling it self is what was giving me that short throat and causing all my seating problems or the 830rds I've put down the pipe has eroded the throat quite a bit .

Now that the bore is squeaky clean and I have the OAL gauge and comparators . I can get the exact measurement to my lands and a whole new seating depth

I gained .035 of throat with the 175gr SMK and that seems like that would be a reasonable number to gain . How ever gained almost a whole tenth of space with the 178gr A-MAX . My seating die was set at 20 thousandths before I cleaned the bore and that kept the bullet just off the lands . Any longer and I'd start to get the marks on the bullet where it was making contact with the bore . I now can chamber a 178gr A-Max that is seated at 110 thousandths on my seater die and it just barely makes contact with the lands . .

Here are the before cleaning the rifle marks on the bullet and the after cleaning the rifle marks on the bullet .
The first pic is before .


The next is after I just cleaned the bore to bare metal . I enhanced the scratch so it will show up in pic but that is where the mark is now . I don't no about you but that seems HUGE to me .


I'm not sure If I should be freaking out or not . Is my throat eroding away faster then it should be or was there really that much build up in my bore ?

It seems pretty clear I measured something wrong the first time but there is another part to this short throat bullet getting marks on it if not seated deep enough . The marks now go all the way around the bullet . The marks were only on one side of the bullet before and really the mark was only on 1/4 of the bullets circumference before cleaning . The first pic looks like it goes all the way around but thats just because I had chambered that round so many times it marked the bullet more then If I had just chambered it once .

If the the issue this whole time was copper , carbon fouling build up in the throat area ,why is there such a big difference with the A-Max then there is with the SMK . why is one 35 thou and the other 90 thou ? Is it as easy as the bullets have different shapes therefore they seat different and were touching different areas when the build up was in the throat ?

FWIW The rifle was still shooting very well before I cleaned it . I was shooting sub MOA out to 300yds no problem . (Then why did you clean it ? )
It was a issue I was having with velocity and I wanted to remove a possible factor . Now I may regret doing so .
http://thefiringline.com/forums/showthread.php?t=533482
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Old October 1, 2013, 04:29 AM   #2
Mike / Tx
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I have found that to be an issue with a couple of rifles. I now use just a touch of carbon cleaner added with a touch of kroil on a patch to swab out the throat area of my chambers when I clean. I picked up a used Sako Hunter in .243, that it literally took almost two full days to get a clean patch to come out of the barrel. The initial couple of passes I had to use a .223 jag just to get a wet patch down the tube at all. When I was done the thing shot the cheapest factory Win ammo into a one hole group.

The only thing I can add is that you might have to tweak your load a touch to regain the previous accuracy or not. Only range time will tell.

As for the differences in length on your bullets, yes the ogive from one bullet to the next can be significant. If you do an internet search for "types of bullet ogive" there will be several good reads brought up. It will also or should bring up a few pictures of the differences involved as well. In most cases I never try to figure my distances to the lands in my rifles. Since I hunt with them all, I simply use the magazine length and go from there. If anything I usually move away from them. In most cases there will be a couple of distances that will hit a good node as you seat away or closer to the lands. Similar to the effect you see while working up a powder charge and having one at the low end that groups well and another on the upper end.

As for the actual throat erosion, this can happen early depending on powder type and such, but is usually more of an issue with a cleaning rod and bore guide that does the most damage. While neither of these may be the case in your example, carbon and copper build up is also an issue that you might keep track of now that you have found it to be an issue. Even if you do not set your loaded rounds to touch the lands, you could make up a dummy round instead that is touching now, and if you check it say every 50 rounds you might find that after a certain number you need to clean the throat again. Depending on the powder and bullet jacket type your using a simple switch to something a bit different might make all the difference in how many rounds it takes to get to that point.

I switched from using Nosler bullets in my higher intensity rounds to Hornady, and got significantly less copper in my barrels. I personally figure that it is simply due to the differences in jacket material as the Noslers are quite a bit softer.

Hope this helps, and good luck with your groups, be sure to post back up after you get some range time in and present the differences if any from before and after. Who knows, you might just go out and shoot your best ever groups.
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Old October 1, 2013, 06:01 AM   #3
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As for the actual throat erosion, this can happen early depending on powder type and such, but is usually more of an issue with a cleaning rod and bore guide that does the most damage.
Please explain how a bore (rod) guide's use causes damage. I've never heard of that.
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Old October 1, 2013, 06:32 AM   #4
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I'm loading 155 AMAX and 155 Berger VLD.
The AMAX at Max OAL touching the lands are 2.845 while the Bergers are 2.890. Even bullets of the same weight will have a different shape from one manufacturer to another and from one lot to another.

I clean after each range trip, which so far doing load work ups, is only 50 rounds the first trip and 40 on the second. I know its a low round count but I haven't noticed any change in my Max OAL yet.
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Old October 1, 2013, 09:39 AM   #5
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Two different bullets, two different bullet shapes. Apples to Oranges comparison.

Jim
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Old October 1, 2013, 12:05 PM   #6
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OK I get the apple to oranges thing . My thought is , if you have different bullets touching the lands or what ever they were touching at two different lengths . Lets say one at 2.800 and the other one at 2.750 . You then open up the throat or free bore space by .050 . I would think the new OAL would match the new free bore space . the 2.800 would be 2.850 and the 2.750 would now be 2.800 . For me It seems I am comparing apples to apples . I 'm comparing the old measurement of the same bullet type and weight to the new measurement . The 175gr smk old OAL was 2.730 , It's now 2.765 the A-Max was 2.750 it's now 2.840 . Why is one .035 difference from last measurement and the other .090 . If I opened up the throat by .050 shouldn't the new OAL on both bullets reflect that same measurement ?

This is why I feel I must of had the original 178 A-Max measurement wrong to start with .
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Old October 1, 2013, 12:17 PM   #7
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the shape of different bullets, their roundedness, changes their touching the lands as you have a .045 difference.
now, because of the difference in roundedness, as you move one back relative to the other you are moving along a different curvature.
demonstrate this with a piece of paper and a French curve. at 2 different points on the curve, as you move the curve back you will see more (or less) difference at the t points.

hope this makes sense; easier to show on paper.

the lands touch the bullet as if a tangent line on a oval
change the ratio of the oval changes the touch/tangent point.

--re-loading, best to make only one change at a time
thus working with 2 different bullets requires die adjustments perhaps approaching the point where inherent error overlaps your ability to makr and keep settings.
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Old October 1, 2013, 12:30 PM   #8
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When a bullet company makes a new mill to make the pointing die used to close the lead cored jacket's front half shaping the ogive and closing the point, it ain't exactly the same shape as the old one. This is why earlier lots of a given bullet may need different setting on the seater die to have the same jump to lands distance as a newer lot. This assumes no erosion of the lead.
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Old October 1, 2013, 12:39 PM   #9
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Metal God-- I follow what you mean. I guess the real test would have been if you still have one round of the old load at 2.80 that was getting stuck. Would have been nice to see if that would chamber good now. I know lot to lot,bullets will change ,but that is a big change you are talking about. When you say it is squeeky clean now- How long did it take you to clean it?. Did your patches keep coming out dirty?. I used to use a bore rod when I first started cleaning also. Then I found out that with the bore Guide in the barrel the part of the barrel the bore Guide is in,Never gets cleaned. I do not use one any more. When I did stop using it I could not believe how many times cleaning it took me to get it clean. I ran the paste cleaner done the barrels first 5 inches and the patch just kept coming out like it was a Plastic patch.

Trash the Bore Guide and you will be better off
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Old October 1, 2013, 01:59 PM   #10
Bart B.
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4runnerman, properly made bore (cleaning rod) guides fit in the receiver and stop against the breech at the back end of the chamber. Never heard of a cleaning rod guide that fit into the chamber's throat and leade preventing any brush or patch from cleaning out that area. Longest ones I know of for centerfire rifles have their front end stopping about mid point in the chamber.

The hole in them's about bore diameter for the barrel. They keep the cleaning rod's outside from rubbing against the origin of the rifling and only let brushes and patches touch the barrel in front of the chamber mouth. While solid stainless steel rods may bend a bit and rub against the rifling, that's never caused an accuracy problem when the right size rod guide's used.
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Old October 1, 2013, 02:20 PM   #11
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Bart you could be right, But The very end of the Bore Guide does sit In the Barrel maybe 1/4 inch or less. Maybe I was using the wrong size end?.
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Old October 1, 2013, 04:33 PM   #12
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Your cleaning rod is made from a much softer material than your barrel is. Unless you are wrapping it up with sandpaper and chucking it up in a drill to clean your barrel, any wear from a cleaning rod is minimal - and that is the worst case scenario.

Concerning the erosion - you also need to factor in that throat erosion is not uniform across the entire circumference of the barrel's interior. You may have more erosion on one area than another, and depending on the ogive of your projectile, that can lead to the fact there are different erosion numbers for different shapes of rounds.
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Old October 1, 2013, 06:40 PM   #13
Mike / Tx
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Please explain how a bore (rod) guide's use causes damage. I've never heard of that.
The idea is to use a "proper fitting" guide when using a bore guide, and as you have mentioned above, some guides may or may not fit properly, but none reach the end of the chamber where the lead and lands are. As such the rod will flex to some degree, and can in practice also damage the throat or lands. How much or how fast can be a combination of several things, but the fact remains if you shove the rod through enough using the wrong tools, it can damage things.

The following link points this out as well.
Bore Brushing

I am not nearly as knowledgeable as most who were asked about cleaing in that link, but I figure if they have seen it I can try and avoid it using what they recommend.

Personally I don't know how new or old Metal god's rifle is, and was simply offering some suggestions and possible advice. Nothing is etched in stone and it is worth what it cost, nothing more or less.

Having built only a couple of custom rifles and putting into them more than I have half of my safe full, I am VERY careful about how I shove the cleaning rods and attached items down the barrel. Again it is simply advice nothing more.

As for not ever hearing of it, well I don't hold that against you. You seem to have a lot of experience with firearms, and you also don't seem like the sort of fellow who has a closed mind either.
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Old October 1, 2013, 07:56 PM   #14
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Mike, synthetic coated steel rods are the safest thing to use if one's concerned about rubbing the rifling too much. Dewey, for example.
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Old October 1, 2013, 09:21 PM   #15
Metal god
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The rifle is new-ish I bought It new in Feb of this year and have shot 840rds through it .

I have a one piece carbon fiber cleaning rod and I do not use a bore guide . No bore guide because I never really used the cleaning rod until a couple days ago .I did not clean the bore much and when I did I used a bore snake . After running the brushes and patches down the bore as many times as I did to get it clean I can see why a bore guide is a good idea . I made at least 100 passes with the cleaning rod . I will add I do know you should be very careful when not using a bore guide and I'd like to think I was . I will be getting a guide before the next big cleaning and that will be much sooner then 800rds .
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Old October 2, 2013, 04:30 AM   #16
Mike / Tx
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Mike, synthetic coated steel rods are the safest thing to use if one's concerned about rubbing the rifling too much. Dewey, for example.
I wholeheartedly agree, and have three or four of them hanging in a rack in the closet. One would usually be sufficient, but I have a couple of rifles with 28 - 30" barrels so the normal length comes up a bit short.

I use several different bore guides and one I built a modified tip for, so as to allow it to reach a bit further into the chamber and help avoid the bend as much. Of course if I could find the stupid thing I might even drag that long barreled thing out a bit more. I just hate to try and shove that long rod down the bore without it.
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Old October 2, 2013, 10:44 AM   #17
Metal god
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synthetic coated steel rods are the safest thing to use
why would any steel rod regardless of coating be safest . I would think any material softer then the barrel material would be safest . that is why I went with the carbon fiber . I have to assume it has to do with the stiffness of the steel rod compared to other materials . less flex makes it less likely it will flex and touch the bore .
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Old October 2, 2013, 04:32 PM   #18
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Carbon isn't a bad thing. Aluminum would be much worse.

Thing is anything which is soft enough for carbon or copper to get embedded in is something to look out for. If it ever gets embedded it is akin to making a rasp which you will shove through your bore time and time again.

I use the Dewey coated rods myself, and I also check them once in a while with a old knee high stocking the wife has gotten tired of. If there is anything that they hang on as they slide down, I immediately find out what it is and remove it. So far out of 4 rods, I have only had one pick up a piece of junk from somewhere. I also wipe them off with a clean cotton towel as I pull them out of the bore to remove anything that might be clinging on them as well.

There are many ways to go about things in life, one simply needs to do a little research and decide how they want to go about it personally. There are untold numbers of rifles out there which have lasted who knows how long with little to no formal cleaning. I picked one up for a song. Thee are also many out there that the best part about them is the stock or the action.
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Old October 2, 2013, 09:54 PM   #19
Metal god
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went to the range and shot the clean bore today . I did not notice any real difference in the rifle and accuracy seem as good as it ever was . I took some loads I knew shot well before and changed the seating depths to match the new distance to the lands and the loads just off the lands just like the others were before . ( well just off of what ever they were hitting before .)I ran 2 different 10rd strings one right at the lands and the other .015 off . all appears to be good I didn't shoot better or worse but the loads that were closer to the lands did shoot just a bit better .
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