6X47 Lapua Question

[ultramagmed]

All,

Just bought me a Bartlein 1:8 twist .237 bore dia. X .243 4 groove barrel.

My current barrel is a Kreiger 1:8 twist .236 bore dia. X .243 4 groove that HAS shot in the mid .100's @ 100yds. (Getting up there in rounds now.)

My question is..............am I gonna see any difference in accuracy / pressure between the two regarding BORE DIAMETER, considering I do my part chambering, fitting, etc. Wide open question.....I Know!!

What are the advantages / disadvantages between the two bore diameters? I mainly shoot 1000 yd. for fun only, but would like to keep the accuracy I have with my current configuration.

Any and all opinions are welcome.

MED.

 

[alinwa]

The kneejerk reaction here is "tighter bores make higher pressure."

I HAVE NOT FOUND THIS TO BE TRUE......

I have no idea why some barrels are "faster" than others but I believe it to be a true phenomenon.

My latest go-round with this, I've recently fitted 6 barrels to two actions with all parts interchangeable..... you can put any one of the barrels on either of the two actions and use the brass from any of the other setups........ In-ter-changeable.

Shilen, Rock, Hart, Lilja and Krieger in SS and CM and the SS Hart makes 100fps LESS velocity with a given load. I also have a reject Rock that's a full .002 SMALLER than the others, so small as to be out of spec. I believe it to be a setup barrel...I'm using it only for fireforming but fully intend to bring it into the testing mix soon just because it does NOT just make loads of pressure.

All's I'm saying is that IMO there is no rule of thumb here. NOTHING predictable IME


opinionby




al

 

[Boyd Allen]

Back in the day, Jackie did a rail gun test of the 6BR with fast twist barrels and appropriate bullets. The test started with a .237 barrel and Lapua bullets did not do well, but others did. A second barrel that was a .236 remedied the problem. The short answer to your question is it depends. If the old dimension worked that well, why would you change?

 

[Dick Grosbier]

If one barrel shoots better than the other it is more likely just one is a better barrel than the other , not the supposed bore diameters.
Some barrels are simply better than others and we are not talking minuscule amounts, many are ok to good , a few are Great. Why are you using an 8 twist 6mm at 100yds? What cal are you shooting? For 100 yd shooting 13 or 14 twist with light bullets would be a better choice. If you are shooting 105-108 vld's in a BR or Dasher 100 yds is not even where you should tune the rifle, 200 or 300 is more suitable and 600 if available.
Dick

oops you did say 6x47L

 

[ultramagmed]

Just to answer some of the above question. The reason I switched bore diameters is simply it was the only barrel I could find without going on a waiting list. The gun is a tactical rifle so I shoot it at various ranges. Tuning was done at 1000 yds. I just used the 100 yd group size just to show how well it currently shoots. I'm not the best 1000 yard shooter so groups sizes at that range would misrepresent its accuracy.
I guess I'll chamber it up and see what I've got, I hope it shoots a good as the last one, I guess I'll find out.

I assume I can expect shorter barrel life with the .237 bore compared to the .236? Any thoughts regarding that or is it even an issue? And yes it is a 6x47 lapua.

Thanks for all the replies, very much appreciated.
MED

 

[SGS]

Just to answer some of the above question. The reason I switched bore diameters is simply it was the only barrel I could find without going on a waiting list. The gun is a tactical rifle so I shoot it at various ranges. Tuning was done at 1000 yds. I just used the 100 yd group size just to show how well it currently shoots. I'm not the best 1000 yard shooter so groups sizes at that range would misrepresent its accuracy.
I guess I'll chamber it up and see what I've got, I hope it shoots a good as the last one, I guess I'll find out.

I assume I can expect shorter barrel life with the .237 bore compared to the .236? Any thoughts regarding that or is it even an issue? And yes it is a 6x47 lapua.

Thanks for all the replies, very much appreciated.
MED

Shorter barrel life because of a .001 larger minor (Land) diameter? Um, no. As to your original question; if it shoots, great. If it doesn't, the .237 bore will NOT be the reason.

Scott Roeder