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Joined: Mar 2002
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Campfire Outfitter
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Campfire Outfitter
Joined: Mar 2002
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Mr. Burns,
Have you found the 3 grove lacking with the 168's around 3000 fps? I was under the impression you favored the 180's. I may try those someday, but will not be near aproaching the 3200fps window, more likely the 2800fps area. You input is appreciated. Bradley, I have only worked with 2 3 groove barrels. One was a 264 Win Mag and we run 140gr VLDs at 3250fps. This barrel shot OK (sub 1/2 MOA) but was not really a great gun and then it started missing paper at 100yds at the 150 rnd point. I actually got a full profile bullet hole (Keyhole) at 100yds with this barrel. I also have messed with a 3 groove 243 Win and it would not shoot VLDs after 200rnd it would still shoot other 105s and 107s but not the VLDs with the J4 jackets. I am personally done working with the 3 grooves because there seems to be no advantage and there is a very distinct disadvantage if you want to shoot the best LR bullets available. I don�t think there is any barrel maker that will guarantee their 3 groove will actually out shoot their 5 or 6 groove so for me why keep messing with something that has never worked as well as the 5 or 6 groove. I am not recommending a particular manufacturer as I think everyone who offers 3s will also do a 6 so why not choose the one that always works with all bullets? John Exactly!
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Joined: Jun 2006
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Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2006
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What would it be that would cause a rifle to start puking bullets at the 150- or 200-round mark, and not right off the bat?
Just curious.
A wise man is frequently humbled.
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Joined: Aug 2002
Posts: 7,445
Campfire Tracker
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Campfire Tracker
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What would it be that would cause a rifle to start puking bullets at the 150- or 200-round mark, and not right off the bat?
Just curious. Heat checking.
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Joined: Jun 2006
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Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2006
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Heat checking causes more friction in the bore?
A wise man is frequently humbled.
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Campfire Kahuna
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Campfire Kahuna
Joined: Jan 2005
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ITs like taking it from "smooth" asphalt to a gravel road more or less.
Its funny though, most of the time barrels finally start to shoot well at a couple hundred rounds down the tube.
And this is the time of the reported blowups.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Joined: Apr 2009
Posts: 1,200
Campfire Regular
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Campfire Regular
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Heat checking causes more friction in the bore? I think you are starting to pick up on it...... A 3 groove has wider lands as well as wider grooves, when the firecracking starts it is much more abrasive with the wider land than with a narrower land of a 4,5,or 6 groove. with a nonolithic bullet it is not much of a problem because at times they wont expand on anything (unless you are a myopic barnes user). The J4 jacket is softer (the Hornady V-Max and A-Max jacket is even softer still). As I stated on the first page the faster the twist and the bigger the case capacity the bigger the problem. 223Rem 1-6.5" twist 3groove 75-90gr VLD bullets will shoot fine, change that to a 22-284 1-6.5" twist 3groove and you will have a hard time getting one to target unless it is a solid. with a 5or 6 groove they will still shoot without blow-up
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Joined: Jun 2006
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Campfire 'Bwana
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Campfire 'Bwana
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Well, I won't be running any of those bullets at the speeds quoted, but I will be getting a 6.5-06 Improved back soon, and want to shoot the Bergers in it. I had considered a 3-groove, got a couple more weeks to make up my mind.
You'd think something like UBC would take care of heat checking, anybody tried that after 200 rounds?
A wise man is frequently humbled.
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Joined: Jan 2005
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Campfire Kahuna
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Campfire Kahuna
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I dont' think you could build up enough layers to fill in the checking, but OTOH any filling should help some.
If I were going a hot little round kinda like yours, I'd sure go 5 groove IMHO.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Campfire Tracker
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Campfire Tracker
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I don't have first hand experience with the issue but did research it before building a couple fast twists.
You have people that say it is no issue to people having issue any where from 300-800 rounds in that they experience the bullet coming apart before loss of accuracy where it previously wasn't a issue.
I have seen some talk of single base powders burning cooler coupled with a good throat short scrubbing with JB bore paste after shooting sessions as helping hold off such issues.
Obviously bullet choice is going to be a big part as to if it becomes a issue and really only in large for bore cartridges.
FWIW.
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Campfire Outfitter
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Campfire Outfitter
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I don't see any reason to take a chance, you don't hear any negative chatter on 4,5,6 groove barrels, if you want a little extra speed go 5R there supposed to be a little faster, and they clean easier too, 3 groove tubes have not proven to be anymore accurate than any of the other groove configurations, if it ain't broke don't fix it!
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Campfire 'Bwana
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Campfire 'Bwana
Joined: Jun 2006
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Talked to Casey form Pacnor a couple days ago, we didn't talk about 3- vs. 5-grooves but he persuaded me to go with a slower twist (9) than I originally thought I needed and I decided on the 5-groove.
He says he and some others were getting really good results with the 9-twist and 140's in a variety of 6.5s, up to the .264 magnum.
A wise man is frequently humbled.
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Campfire Tracker
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my 1-9" twist would not stabilize the 142 SMK but would shoot the less aerodynamic 140 SMK fine. that told me it was right on the edge, not where i like to be.
i've been hamstrung by slow twists enough that i don't budge. i'll never order another .224" or .264" barrel slower than 8". the 'that's what the benchrest boys like' or 'you'll loose velocity' arguments don't wash. i'm not shooting for aggs in the single digits in the second decimal place, and the velocity loss due to twist rate is lost in the background noise of other factors affecting velocity...
i don't have a 6.5-'06, but i'd guess you'll be near .264 speeds. at those speeds, you will not want to dick around trying a bunch of different bullets and looking for 'nodes', else you'll burn up a bunch of barrel life before ever settling on a load. my suggestion is to try a bullet you can easily get that also fills your needs seated to the lands over IMR 7828 (work up to pressure signs your comfey with), and if that load works run with it.
Guns don't kill people, drivers with cell phones kill people.
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Campfire Kahuna
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Campfire Kahuna
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And... what if ya get a good load at 80 and its -10 when you need it to work....
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Campfire 'Bwana
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Campfire 'Bwana
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Talked to Casey form Pacnor a couple days ago, we didn't talk about 3- vs. 5-grooves but he persuaded me to go with a slower twist (9) than I originally thought I needed and I decided on the 5-groove.
He says he and some others were getting really good results with the 9-twist and 140's in a variety of 6.5s, up to the .264 magnum. Smokepole, What's their thinking, favoring 9 over 8.5 or 8 twist? DF
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Joined: Jun 2006
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Campfire 'Bwana
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Campfire 'Bwana
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Well, I don't want to put words in his mouth, but basically they had very good results with 140 Bergers and a variety of .264s so a faster twist is not needed.
A wise man is frequently humbled.
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Campfire Kahuna
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Campfire Kahuna
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an inch faster twist has never hurt any firearm I've ever had built. Of course I have not demanded BR type accuracy in the zeros or ones... but I do demand .5 moa and prefer as close to .25 moa as I can get if possible.
The problem I just see is that its hard to overstabilize if thats even a word, but if you have almost enough, but not quite... you can't fix that easily or cheaply.
Per Toads report... I'd say it would be too close to the edge of stability for me too.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
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Campfire Regular
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Campfire Regular
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This is part of the problem, talk with other barrel maker's. for your combo of a 6.5-06 wanting to shoot 140gr VLD Berger's my minimum twist would be a 1- 8.5" with a minimum of 4 grooves.......in this senario my first choice would be a Krieger.
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Campfire Tracker
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and the velocity loss due to twist rate is lost in the background noise of other factors affecting velocity...
I not only agree with this statement but don't think a fast twist rate slows down possible velocity at all. Can't remember where but I once saw some pressure data that didn't show pressure spikes due to twist. Mainly the initial engraving regardless of twist.
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Campfire 'Bwana
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Campfire 'Bwana
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.......in this senario my first choice would be a Krieger. Then by all means, when you order your barrel, make it a Krieger.
A wise man is frequently humbled.
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Joined: Jun 2006
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Campfire 'Bwana
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Campfire 'Bwana
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my 1-9" twist would not stabilize the 142 SMK but would shoot the less aerodynamic 140 SMK fine. that told me it was right on the edge, not where i like to be. Well, hearing that some have not had 140s stabilize in a 9 twist does give me pause, and I still have a couple weeks before they get to my barrel, thanks for the input, always good to hear first-hand accounts like this.
A wise man is frequently humbled.
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