Number of grooves?????

S

S.G

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What seems to be the best number of grooves for 6BR 600-1000yrd.
We are using a 1:8twist, 30 inch long barrel. Bullets will be 105-108gr berger , JLK , clinchrivers maybe sierra.Thanks
 
The number of grooves? To me the number of grooves has no real bearing on accuracy or barrel life! Some say if you want hard core accuracy go with conventional rifling vs. a 5R type barrel. Some say the 5R's copper foul less. I say B.S. I've seen 5R copper foul with the best of them. Some say the 5R barrels will seal the bullet better in the bore and you get more velocity out of it. Again I haven't seen this either. Some say the 5R barrels don't leave a burr on the bullet and will drift less in the wind. I haven't seen this either.

99% of the barrels we make for short range bench shooters are 4 groove conventional rifling.

Across the course high power shooters seems to be a 50/50 split.

Long range prone shooters seem to prefer the 5R.

Long range bench shooters I would say the preference is more towards conventional.

I've got a conventional 5 groove (not 5R) on my short range bench gun. Wanted to try it! The gun hammers!

I've shot 5R's and 4 groove in prone matches out to a thousand and even compared both in the same match (two man team) and saw no difference. Our team came in 3rd place in that match. Same chambers, same loads! Both guns we're chambered in 6mm Rem with a custom throat. Shoot mostly Berger 105's and Sierra 107's. Both are 1-8 twist. Velocity difference between the 2 is 30fps. The loads average 3155fps between the two. In the match where we shot both on the same relay at the same time. We didn't use anymore or any less windage on one gun vs. the other.

To me it is more of the quality of the barrel blank. The straighter, the more uniform your bore sizes and the more uniform the twist the more forgiving it is going to be.

Hope this helps!

Frank @ Bartlein
 
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One quick last thing I forgot and this one is open for debate also. Some will say that the odd number of groove barrel will help with jacket failure. This is because the odd number of grooves vs. an even groove barrel will distort or upset the bullet jacket less. This is because the lands don't directly oppose one another. I believe this has some merit but is hard to prove.

I compared a 6mm 5R and a 4 groove in the match mentioned above. The 4 groove was the second barrel in a row that would blow up one manufacturers bullets but not another. So for awhile I stopped using the one bullet. Got to scared to use them. So I wanted to see what would happen. Bought some more of those manf. bullets and guess what? No failures in either one. So in away that kinda blows the theory.

Both barrels we're made to the same bore and groove size and same twist. Same chamber reamer was made in both of them and the same loads shot thru them. Why didn't the one barrel blow up anymore of the one style of bullets. I chalk it up to being a different lot. Maybe the one lot I got had problems with the cores? Hard to say!

Frank
 
Check out the thread records fall at Sacramento shot at 600 yards.

Craig ST. Claire shot a 1-8 twist, 4 groove chambered in 6BR, Bartlein barrel, smithed by Stu Harvey.

Frank
 
Frank Green

Frank what are your thoughts on the 3 groove 6mm barrels lasting longer do to the cross section size of the land?

I was at that match in Sacramento and Craig StClaire was a very happy camper with your barrel.
Lynn
 
Frank, thanks for the great insight into 4 and 5 groove barrels. I also heard something similar to what lynn is asking about, your thoughts please.
 
Lynn, The match donation certificate will go out in the mail this week to you.

Your question about the 3 groove barrels?

Again I don't see a difference in the number of grooves effecting barrel life etc...One barrel maker who is making 3 groove barrels the last I heard was claiming they last longer. This might be true in a button barrel because of the wider lands. On average I don't see a button barrel lasting as long as a cut rifled barrel. Why?

Because the button rifling operation work hardens the bore. I'm not saying a button barrel will not go a long time or a cut barrel can burn out early as I've seen both. It's just what we see on average. Can I put a number on it. Not really but if I had to about 20% longer on cut barrels. Keep in mind there are alot of variables that effect barrel life. One guy shoots a powder that is more abrasive than another is an example. Not to mention the steel from one lot to another even if you are getting the steel from the same supplier can be a variable. The list doesn't stop almost.

When we we're at Krieger back around 1999 or 2000 Tracy made the tooling for 3 groove .30cal. palma barrels and we made a couple of tight bore .30cal. barrels that we're made for Mid Tompkins. Mid told me that accuracy wise out to 800 yards they shot just fine compared to the 4 grooves. The only problem was both barrels we're a flat 100-150fps. slower than his 4 grooves so they wouldn't cut it at 900 and a 1000 yds. due to the velocity loss. Why? Maybe because of the wider lands? Hard to say sometimes but that is my guess.

Also at Krieger before we we're gone we made a cut rifled barrel and a button rifled barrel in .224 cal. for John. He chambered them in .22-250 and put them on some prairie dog rifles and was taking them out west. They we're made out of the same lot of steel and got the same loads thru them. Accuracy wise both shot great but the button rifled barrel was exhibiting more wear with the same round count on both. Both barrels we're being shot in the same conditions and same loads we're being run thru them.

I've seen 2 groove, 3's, 4's, 5's and 6's all shoot excellent so again I say there is no difference in accuracy or barrel life. But when you compare one or the other you should be comparing/testing the barrels being made out of the same lot of steel and being made from the same maker and being shot in the same environment. This is the only way to get good results but who has got the time, money etc...to do this? That is the hard part.

Also it is funny you should ask about 3 groove 6mm's. Around Christmas time we we're talking about making some and getting them out in shooting community to get feed back on them. I will keep you posted on this.

Talk to you later, Frank
 
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Frank Green

Frank thanks for the 3 groove barrel info and a big Thank You on the barrel certificate!!!!!!

To those planning on making it to the NBRSA 600 Yard Nationals in Sacramento this April we have a Bartlein Barrel certificate as a prize!!!!!!!!! Come on out and shoot with us and maybe win a Barlein Barrel while having fun too.
Lynn
 
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