Severely Overbore Chartidges and short barrel life myths...

[Elkslayer1]

Thanks Kirby,

If you get verticle stringing does that mean that you need more OAL adjustments or do you then start changing the powder charge to?

From 10 to 15 thous do you then start to go further in until you get a round consistent group?

Thanks, Elkslayer

 

[SHRTSHTR]

Kirby,

I think i actually started at 92 gr Retumbo when I was fireforming loads. I worked up from 92 gr and when I had fireformed cases took it up to 102 gr.

This rifle has a 30" Lilja #8 countour, 1-10 Twist. I have been loading .020 off the lands with Fed 215 mag primers. My ES is running 10fps over a 10 shot string.

Would really like to know if CCI-250's would work in this 338 LAI. I am happy with 2,940 fps. It is on the top end velocity wise for what I was hoping for. This rig seems to hit my AR steel a lot harder than my 338 Lapua did. It might be my exaggeration though.

 

[B23]

That 100-102gr of Retumbo and a 300SMK in these 338Lapua imp. must be the sweet spot or something.

One of my buddies has one of Kirby's 338AX and he loads 102.3 or 102.6 dont remember exactly but I know it's one or the other but with that load and his is a #5 27in Lilja we got 2935 for a low and 2946for a high on my CED M2 and it was well under 1/2MOA. I thought that was pretty **** good for a, w/NF scope, 11lb rifle.

 

[Michael Eichele]

If it was not for my problems with not one but two 300 RUM barrels, I would agree with you a lot more than I do. Please dont take this as that I dont agree with you, I just dont agree with you 100%. You make a very valid point about the care one takes with his barrel. I can testify that although the 338 Edge is a 'barrel burner', I let her cool for a MINIMUM of 2 minutes between shots. End of story. There have been 2 occasions where shots were fired back to back and they were both during the hunt. Now, after 250 rounds I bore scoped the barrel and guess what? The barrel, including the throat looks brand new. No heat cracks, no errosion canyons, nothing. Another thing (and this is a big one) I dont run high pressure loads through her. The 300 RUM's however I hot rodded. Even though I never fired more than 3 shots in a string, they still crapped out pretty fast. One was less than 100 rounds. The other settled down after a couple hundred and it shot well after that till the 1150 round mark.

Regards.

M

 

[Fiftydriver]

Elkslayer,

Generally, if I get vertical stringing, I will seat the bullets to the lands and see what happens. Most times it will tighten up but this is not written in stone. Other times you need to go the other way. This is mainly with factory rifles. With match barrels and tight throats, I have found that OAL has very little to do with velocity spreads or accuracy results but you must remember that my throats are no more then 1/2 thou over bullet diameter and its common to chamber a loaded round, eject it and see where the throat has rubbed around the bullet when chambered because the throat is this tightly matched to the bullet.

This does not allow the bullet to get out of alignment with the bore and as such, oal is not as critical nor does it seem to vary accuracy as much.

Now a factory barrel, 50 thou can make a HUGE difference in accuracy.

Important thing it to change one thing at a time so you know what makes a difference.

Remember back in my load development post, when I shoot 4-5 shots over the chrono, for the most part, that right there will tell me if I am going to see any vertical stringing and how much I can expect.

I have also learned that when LR shooting, if you get vertical stringing, one of the first things you should do is check your baring surface consistancy of your bullets. If needed sort them so they are all the same baring surface length. This can make a big difference.

 

[Fiftydriver]

SHRTSHRT,

In my experience, the CCI-250 needs one extra grain of powder to match the velocity of the Fed-215 primer. Other then that, with stick powder, they seem to do quite well but they are not as hot as the 215s so velocity will normally be a bit less.

That said, the Fed-215 MATCH primer also needs on average 1 grain more powder to reach same velocity as the standard 215. That is why I always use the standard 215, just hotter.

 

[Fiftydriver]

Michael,

Certainly you know me well enough by now to know that I fully realize nothing is set in stone so your comments do not suprise me at all. I have also seen certain barrels give up the ghost MUCH sooner then they should have even when cared for properly.

In my opinion, that has more to do with a certain barrels alloy make up because on average, if you do not overheat a quality barrel it will last a long time.

I have seen some factory SS barrels let go in a couple hundred rounds. To be honest, I feel alot of this has to do with the throat length and diameter. They are loose enough in the throat that it allows the hot gases to blow by the bullets sidewalls and this flame cuts the throat and the origins of the rifling MUCH more then if the throat is cut to precisely match the bullet diameter.

I personally believe that throat fit is one of the most important aspects to a good throat life.

NO problem at all not agreeing with me 100%. There are always experiences that others have had that we all learn from. Thats whats great about this site, all the telling and sharing that goes on. Offers huge amounts of education to all of us and I fully understand my experience is a small part of the vast experience on this site and I am glad to share my tests with whoever wants to read them and hope others chip in with all their experience as you have, I learn just as much from that as well.

Thanks for your reply and imput.

 

[LRHWAL]

Great thread.

I can confirm that the one shot per powder charge works great; even for factory rifles.

I first did it after buying expensive (like $2.50 ea) big game bullets for my 375H&H and having no idea of where to start. I've also sometimes set up a little stand for a cheap press and filled old 35mm film canisters with powder and loaded at the range. I took everything pre done except for seating. Not being set up for range loading I was surprised at how well I managed.

It saved me a bunch in load development.

I will test an unexpected result of one shot again if relevant. Once IO have the velocity I'm looking for I tinker a little around there.

 

[Hicks]

My US Model of 1917 Eddystone shoots .75moa, and it has a naked eye visibly eroded barrel.

Wait... What?!??! Tell me that's an '06! I have my grandpa's Eddystone, which I put a Vari-X III 6.5 - 20 x40 on and swapped to a Bell and Carlson synthetic. Factory bbl and a nice Canjar trigger. I haven't bedded the action, but it looks like it fits really tight in the stock and the bbl is floated up to about an inch infront of the lug. He was able to shoot little bitty groups, and the last elk he killed was out past 500 yards. I've played a little bit with the 168gr SMK, but the accuracy was poor. What is your load?

Hicks

 

[Hicks]

Kirby,

Quick question with a little background. I smoked a bbl on my 7RUM trying to get the 180 Bergers to shoot with anything more than about 2MOA accuracy at 100 yards. Before that I found the 160gr Accubonds would do about 1/2 MOA at 100 yards with 92gr of Retumbo at just about 3200fps. I killed a nice antelope buck at just about 500 yards in the Thunder Basin 2 years ago, as it ambled after a group of does. I have to say I was impressed with the shot, and the gun would do much better than I am capable of. However, the terminal performance was less than poor. First shot clipped the back of the lungs, and the buck stood, obviously dead but didn't know it, at a high quartering angle, what Elmer would have called a raking shot. I put another one in him as he stood still, and upon examination tha round entered just in front of the left hip and exited just in front of the right shoulder, while the first round hit a rib on the way in. BOTH rounds made little bitty holes going in and little bitty holes going out. In fact the second round brought some gut material with it through the front shoulder. My question to you, and whom ever else wants to chime in: What's been your experience with the Accubonds? The only conclusions I could make were that either the 7mmRUM couldn't push that bullet fast enough at that range to make it expand, or that those bullets are simply too tough and weren't designed for game that thin skinned.

That next summer I started on with the Bergers and simply couldn't get the accuracy with any powder I tried. I went back to the Accubonds and found that my groups had swelled to well over 2" and in frustration I ordered a bbl vise and wrench and pulled the bbl, earmarking that action for a 338 Edge build. I have to say that reading your posts has made me yearn again for my pet 7RUM!

 

[SHRTSHTR]

B23,

2946 fps out of a 27" barrel seems very good to me. 1/2 moa out of a 12lb big magnum is outstanding. I think it says a whole lot of something about the rifle and the shooter. gun)

 

[SHRTSHTR]

Kirby,

Thank you very much for the info. It seems I am on the right track with my rig.

Now the big question, what kinda of barrel life can I expect from my 338 LAI? I do baby this rifle. I have never shot more than 3 shots, 1-2 minutes apart. I let the barrel cool down comletely before shooting another string.

I am purely guessing but I am hoping for 1500-2000 rounds. How far am I off?

May not be able to reply until Monday, I leave for Antelope hunting in about an hour . This will be my biggest test this year. I shot a bear last week at 523 yards. one shot trap doored him. Hoping for a little further this weekend. We have 10 tags here in Colorado.

 

[Michael Eichele]

Kirby,

What in your opinion are some of the better steels out there? (As far as manufacturerers). I definatly noticed a big difference between one of my barrels in the same chambering as another as far as life was concerned. Some shooters are also of the opinion that button pulled barrels hold up better than cut rifled barrels. Do you have an opinion on that?

Interesting observations about throat lengths and demensions. I never thought of that.

M

 

[B23]

SHRTSHTR

LOL I can assure you the shooters had the LEAST to do with it. I'm going to give all the credit to the gun and the load.