Groove discussion

[FrankG]

Now that the groove vs velocity question has been answered, let's circle back to the original question, what is/are the reason(s) that one would choose a 4, 5R or 6 groove barrel rather than one of the others?

The one thing I do believe in with the 5R (and this doesn't apply to all odd groove barrels) is that the odd number of lands and grooves the lands don't directly oppose one another. This will distort/upset the bullet jacket less and this will help fight bullet failure. Bullet failure is higher in the smaller calibers like .224 and 6mm. Not much of a problem in 6.5's and bigger calibers.

Bullet failure is more of a problem for a long range shooter then a short range shooter. I've seen it personally with 6mm bullets and I did trace it back to the lot of bullets had a problem with them. Most shooters take the bullets for granted and as soon as they have a problem with accuracy or anything else they are quick to point the finger at something else and usually don't think of the bullet.

An even groove/land barrel the lands will directly oppose one another. Also in 3 groove barrels because the lands are much wider you still get part of one land opposing another so you don't get the true benefit of the 5 groove/5R type barrel.

For the most part the number of grooves has no bearing on accuracy either. The only exception to this rule is with 6mm with short jacket bullets like the 65-68gr. bullets with the 6ppc type guns. Those short jacket bullets don't like the 5R rifling. I tell guys they will shoot in the upper .2xx's to flat .3xx's but that's all you will get out of them. So I'm against making a 5R barrel for a PPC shooter because of this. My 6PPC has a conventional 5 groove barrel and it's a hammer. it's not a 5R.

Shooting bullets over say 85gr. in 6mm the longer bearing surface of the bullet has more for the rifling to bite on to and they don't seem to care.

I've shot barrels from everything from 2 groove up to 8 groove in calibers from .22rf up to .338cal. and for the most part I don't see a difference with the style or number of grooves with the exception of the short jacket 6mm's I described earlier.

I do lean towards the 5R cleaning easier from a carbon fouling stand point vs. conventional rifling. This is because the patch isnt' trying to get down into a 90 degree corner next to the land. As far as copper fouling goes I don't see a difference. Some say the copper fouling cleans easier in a 5R style barrel but I don't see a difference.

Some say if you want hard core accuracy you want conventional style rifling (not 5R, polygonal, ratchet etc...) but the question I put back to guys are these...What are you using the gun for? What are your accuracy requirements? Then I go from there.

Later, Frank

 

[FrankG]

Is the "R" (radial) designation mean similar to polygonal rifling?

5R and polygonal are totally different.

We made a polygonal test barrel just two months ago for a ammunition / bullet maker. Accuracy wise fine/o.k. but velocity was down compared to a 5R or a 4 groove barrel.

I don't see a polygonal rifled barrel (on a rifle) shooting as accurate as a 5R or a conventional style rifled barrel. To me rifle bullets are more temperamental then a pistol caliber/pistol bullets.

You have to keep in mind the lands do the driving to the bullet and not the grooves.

Later, Frank

 

[FrankG]

Another comment I've gotten on 5R style barrels besides accuracy and cleaning and velocity etc...is that they help the bullets drift less in the wind. When a shooter tells me this I ask them to explain they're reasoning behind it. They say the 5R rifling doesn't leave a burr on the o.d. of the bullet and with out the burr being there they don't catch the wind/air as much and there fore drift less in the wind. O.K........

but for the most part the air on the side of the bullet is dead air in my opinion as the bullet is typically going supersonic. So if the rifling is leaving a supposed burr on the side of the bullet it doesn't mean anything really.

I shot a 4 groove and a 5R barrel on two rifles. I chambered both of the barrels with the same reamer (6mm Rem.) and shot both guns in a 2 man team match with the same exact ammo loaded at the same time at a 1k yards. The velocity between the two guns was within 30fps. Same wind conditions etc....guess what? We didn't have any more windage on one gun vs. the other gun. So I don't see it.

Later, Frank

 

[RGRobinett]

5R and polygonal are totally different.

We made a polygonal test barrel just two months ago for a ammunition / bullet maker. Accuracy wise fine/o.k. but velocity was down compared to a 5R or a 4 groove barrel.

I don't see a polygonal rifled barrel (on a rifle) shooting as accurate as a 5R or a conventional style rifled barrel. To me rifle bullets are more temperamental then a pistol caliber/pistol bullets.

You have to keep in mind the lands do the driving to the bullet and not the grooves.

Later, Frank

Frank, the last thirty Cal., 1:18" 5R, you sent me was chambered for 30BR, and shot during the VfS stages, at the recent NBRSA Score Nationals.

Prior to leaving home for Lake Charles, LA, I went to the range & loaded six rounds with my, "cookie-cutter", formula: those first 6ix shots [out the barrel] made a nice .195" 100 Yd. group! That concluded the , "load development". ;-) The first shot out of the barrel "ruined" a nice ZERO group - it was about 1/2 a bullet high/left of the following five!

I pre-loaded, and the rifle continued to shoot extremely well, garnering a 3rd place finish (500-31x) in the 100/200 Grand Agg. I must confess, I was a little afraid of the 5R profile for the short/light bullets - this is one GREAT barrel. Oh, I clean only following a yardage aggregate (including the "warm-up match,40-45 shots), and upon doing so, there was ZERO copper on the patches. RG

 

[FrankG]

Nice shooting Randy!!!!!!!!!!!!!!

Thanks for the update! Haven't made many 5R .30's in the slow twist rates like yours.

Later, Frank

 

[mauser284]

Nice shooting Randy!!!!!!!!!!!!!!

Thanks for the update! Haven't made many 5R .30's in the slow twist rates like yours.

Later, Frank

My experience with polygonal rifle barrels is that while accuracy is just ok as in fine for F T/R , hunting, Silhouette etc... their strength is that often they will shoot many loads really well and clean up super easy. So for people that do not reload polygonal rifle barrels offers a large leap in acceptable accuracy with much more flexibility in load selection.

My sample size is rather small but I do get around in a lot of the small regional competition circles and with guys that do less formal tactical type competitions and such and this seems to hold true. A lot of polygonal rifle barrels on the global market are hammer forged which is a real turnoff to 99.9% of Americans building custom rifles.

I am a fan of CHF barrels for any rifle that is not a bench rest rifle that needs to have long barrel life and what I call acceptable accuracy. So military sniper rifles, anti-material rifles, DMR, machine guns, hunting rifles etc.... Just like not all button rifled barrels are BR level barrels CHF cover the gambit between fantastic barrels and OEM pond scum! LOL Cleanliness, maintenance on those mandrels, material selection and how many heat treat stabilization step are performance is key!

One of my favorite Silhouette rifles has a CHF barrel on it! It would never hold up to BR standards but on the Silhouette line she is a gem! I have no doubt a Bartlien(SP) barrel would perform better of that I am sure! I have never come across one at a great price in fact my Brux barrels have always been far cheaper and that is the only reason I have yet to try one! I have shot against some of your barrels and checked them out and they are definitely top notch barrels that is for sure! In fact Frank your barrels are some of the only ones I have not tried due only to price point!