Opinion on Benchmark 2 grooves barrel

E

Evelio

Member
I have a new Turbo with a new 2 grooves Benchmark barrel, mounted on a Mc Millan edge stock, pillar bedded, with a Myers chamber, and toped with a Nightforce 12x42 benchrest scope.
Using Ely Match ammo. it will shoot a bug hole for about 5 to 6 rounds then it will throw a 7 using a USBR target, next shot would be an X tried it with several good lots of ammo. that shoots great on my Rachet, and Lilja barrels, but normally the Benchmark barrel will throw at least 2 shots on a card.
I also tried Lapua Midas Plus and have shot several 245, and 3 247/ 6 & 7 Xs and it shoots bug holes all day long. My question is: Does the two grooves barrels performed better with a round nose bullet versus the EPS bullet.
Anybody out there experienced the same problem ?
Evelio.
 
There is a 2g reverse taper on a used Hall I bought that shows a lot of 6 o'clock bore erosion. At the last match I loaned it to a shooter and she used some Center X her dad had. Her 50 yd scores were a 246-7 and a 250-13 { RBA target }. The 250 target only had 4 sighters and she says she shot them after the record rounds. Warps the mind. So they will definitely shoot round nosed bullets. I shot a 243 and a 245 with it back in Sept so it definitely likes her lot of Center X better than mine.

I haven't tried it with any Eley since I got the rifle.
 
Another thing. I borescoped the bbl when I first got it and the throat is noticeably offset to one side. If you think about it it would be almost impossible for the pilot of the reamer to keep the reamer perfectly centered. The way thing shoots makes a mockery of the levels we go to to have the chamber perfectly centered.
 
I have a Benchmark 2 groove 1-16.5 twist, reverse taper barrel, that Gene Davis installed on my 40X 4 years ago, and it is still shooting bug holes with selected Eley Match. I have had the barrel checked each winter with a bore scope and the barrel remains in excellent condition. I have had an occasional flyer with my 40X, but most of them I can contribute to either the ammo or to my fault.. I don't know if it is my cleaning procedure that is keeping this BM barrel shooting or if it is Gene's masterful installation job. I know that, if and when I do need a new barrel, I will let Gene put another BM 2 groove on my 40X..

Dave
 
Evelio said:
I have a new Turbo with a new 2 grooves Benchmark barrel, mounted on a Mc Millan edge stock, pillar bedded, with a Myers chamber, and toped with a Nightforce 12x42 benchrest scope.
Using Ely Match ammo. it will shoot a bug hole for about 5 to 6 rounds then it will throw a 7 using a USBR target, next shot would be an X tried it with several good lots of ammo. that shoots great on my Rachet, and Lilja barrels, but normally the Benchmark barrel will throw at least 2 shots on a card.
I also tried Lapua Midas Plus and have shot several 245, and 3 247/ 6 & 7 Xs and it shoots bug holes all day long. My question is: Does the two grooves barrels performed better with a round nose bullet versus the EPS bullet.
Anybody out there experienced the same problem ?
Evelio.
Click to expand...

Have shot 2 grooves for a few years now. On my current one, there is probably around 6-7 cases through it. Has shot great right from the start. For the first 4 - 5 cases we cleaned it with brush and patches. But of late we have switched to just a few wet patches in between cards and after 1/2 brick or so a stroke or 2 with the brush. If you are getting shots thrown, try a little flitz in the chamber area, and then clean it as usual.
 
Evelio said:
I have a new Turbo with a new 2 grooves Benchmark barrel, mounted on a Mc Millan edge stock, pillar bedded, with a Myers chamber, and toped with a Nightforce 12x42 benchrest scope.
Using Ely Match ammo. it will shoot a bug hole for about 5 to 6 rounds then it will throw a 7 using a USBR target, next shot would be an X tried it with several good lots of ammo. that shoots great on my Rachet, and Lilja barrels, but normally the Benchmark barrel will throw at least 2 shots on a card.
I also tried Lapua Midas Plus and have shot several 245, and 3 247/ 6 & 7 Xs and it shoots bug holes all day long. My question is: Does the two grooves barrels performed better with a round nose bullet versus the EPS bullet.
Anybody out there experienced the same problem ?
Evelio.
Click to expand...

Are you sure it's not your new turbo? The last time I had flipper shots it was an action problem that my smith fixed in about 15 min. About 2 hrs later, it produced a 2500 Ara. I have a couple of benchmarks too, one has over 130,000 threw it, and it still shoots great. Also a stock problem may cause that as well. Good luck with your new rifle.
 
Jerry W said:
Dave - would you care to share your cleaning procedure for that barrel?

Thanks,
Jerry
Click to expand...

Jerry....

I run two wet patches and three dry patches down the barrel after each card. After each match, I run one wet patch, followed by four or five strokes with a wet brass brush, followed by another wet patch and finish up with three dry patches. At the range, I use Boretech Rimfire Blend and after the match, at home, I used Mercury Power Tune Outboard Engine Cleaner on both the patches and the brush.

Dave
 
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The Benchmark barrel shoots the Lapua ammo. great, my problem is with the Ely EPS bullets, that's when it throws one out every 6 or 7 rounds. It does it with a clean or dirty bore, and not in the same area, very frustrating. I have several cases of Ely Black that's why I keep trying it.
RLB 40X, what did your gunsmith did to fix your Turbo action ?
The damm thing will shoot the Lapua great all day long, so I can't blame the action or the stock, so that leaves the chamber configuration or the 2 grooves as the culprit. Don't know what else to try.
Evelio.
 
Sell the Eley

Evello,
Have you considered selling the eley & buying the Lapua it likes. Seems like that would be thing to do. End of problems.
Keith
 
Linekin,
The Ely that I have shoots fantastic on my two 40x and even better on my Anschutz 54, no chance on getting rid of it.
Evelio.
 
Evelio said:
The Benchmark barrel shoots the Lapua ammo. great, my problem is with the Ely EPS bullets, that's when it throws one out every 6 or 7 rounds. It does it with a clean or dirty bore, and not in the same area, very frustrating. I have several cases of Ely Black that's why I keep trying it.
RLB 40X, what did your gunsmith did to fix your Turbo action ?
The damm thing will shoot the Lapua great all day long, so I can't blame the action or the stock, so that leaves the chamber configuration or the 2 grooves as the culprit. Don't know what else to try.
Evelio.
Click to expand...

Evelio,

I wouldn't blame the barrel, it shoots Lapua great. It's more likely the chamber. Just curious how much engraving the 2 bullets differ.

Regards,
Joe
 
Evelio said:
Linekin,
The Ely that I have shoots fantastic on my two 40x and even better on my Anschutz 54, no chance on getting rid of it.
Evelio.
Click to expand...

Evello
Glad you have rifles the eley shoots well in. That's alot to have for a gun that doesn't like it! A good luxury to have!
I'm curious as to the twist rate of your Benchmark as I was told to stay away from the slower twist barrels as I shoot in sometimes cool temps.( ME) It is often below 60 in the spring & fall in the mornings.
I also have a Benchmark & was seeing something similar. Turns out that my barrel although shot well occasionally would have fits as well. My barrel is just used up.
Another thing I noticed was that when I changed rows on a card sometimes the first shot was off. I started shooting a couple sighters before I shot for score & that helped quite a bit. So I have to work on my rest setup so this is less likely to happen.
Hope you figure it out.
Keith
 
Joe
The chamber engraves just past the first band on both type of bullets.
linekin.
The twist on the BM barrel is 16.5" The Turbo action is only 2 months old, the Ely ammo. was purchased before the Turbo was build, and really is all I shot on my other benchrest rifles. I won a brick of the Midas + and tried it on the Turbo out of desperation, and as I stated before, it shoots great in it, with no flyers.
 
Evilio

Evelio said:
The Benchmark barrel shoots the Lapua ammo. great, my problem is with the Ely EPS bullets, that's when it throws one out every 6 or 7 rounds. It does it with a clean or dirty bore, and not in the same area, very frustrating. I have several cases of Ely Black that's why I keep trying it.
RLB 40X, what did your gunsmith did to fix your Turbo action ?
The damm thing will shoot the Lapua great all day long, so I can't blame the action or the stock, so that leaves the chamber configuration or the 2 grooves as the culprit. Don't know what else to try.
Evelio.
Click to expand...

I think you are missing the most probable thing, the tuner settings, I suspect your tune is off and I would suggest trying the Purdy prescription, test every harmonic and you will find you are on a peak of the wrong harmonic in your tuner setting.I have had the opposite happen to me where Eley shot great and Lapua would shoot several great then throw one, I found the gun was out of tune.

Mike Cameron
 
Mike
My barrel is 24 1/2" and tried the PRX for the 9th harmonic at -0.187 and was within two clicks from shooting bug holes, I also tried the -.402 and it also shot great. I am talking 15 shots groups at 50 yds. all inside the 10 ring on a USBR target, the Ely would do the same except a fu______ 7 out of 14 inside the 10 ring. Perfect conditions, Pappas rest, and Nightforce scope.
The flyers occurred consistently, in each group fired with Eley. The reason I shoot 15 shot groups is because every time I shot a 5 shot bug hole, I figured OK I got it, then I shoot a card and an 8 or 7 will pop up out of nowhere.
Evelio.
 
Evelio said:
Mike
My barrel is 24 1/2" and tried the PRX for the 9th harmonic at -0.187 and was within two clicks from shooting bug holes, I also tried the -.402 and it also shot great. I am talking 15 shots groups at 50 yds. all inside the 10 ring on a USBR target, the Ely would do the same except a fu______ 7 out of 14 inside the 10 ring. Perfect conditions, Pappas rest, and Nightforce scope.
The flyers occurred consistently, in each group fired with Eley. The reason I shoot 15 shot groups is because every time I shot a 5 shot bug hole, I figured OK I got it, then I shoot a card and an 8 or 7 will pop up out of nowhere.
Evelio.
Click to expand...

The 9th harmonic would give you a tuner length of 2.87 inches, Not .187.The 7th would be 3.89 inches, the 11th would be 2.26 inches. 2.87 is somewhere near 450 on the tuner register. You may want to redo your PRX calculations.

Mike Cameron
 
Evelio:

I really like the 1.5 degree chambers for round nosed ammunition - I have several reamers with this throat profile.

IMHO, the 1.5 degree leade outperforms the 2 degree - especially for Lapua ammunition, but it has to be setup properly (the 2 degree also performs well, but I get slightly better overall performance with the 1.5 degree and Lapua ammunition). If I was planning to use / test both Eley / Lapua, I would definitely stick with the 2 degree leade angle.

The trick (in my opinion) using a 1.5 degree leade reamer is using a little less engraving length. The absolute maximum engraving dimension for Lapua ammunition is about .180" (if you remove the lubricant from a round, and place it in a fresh chamber - this dimension would be from the chamber face to the face of the rim), or about .220" from the datum to the bolt face. I just finished some testing this fall with similar large amounts of engraving (thinking more engraving was always better) - but it was not. The barrels would shoot well (very well) for a very short round count. As the barrel fouled, you would still see great accuracy, with the occasional erratic shot.

As I increased the chamber depth, the problem goes away - accuracy is still awesome, and the barrels seemed much more tolerant regarding cleaning intervals. My current setup is approx. .090" engraving (.130" from the datum barrel face to the back of the cartridge case). The results were consistent across multiple barrels / rifles.

In my opinion, the shallower leade (especially when heavy engraving is used) reduces the diameter around the juncture between bullet and case (where all / any buildup accumulates). Moving the leade forward allows some small amount of additional clearance at this juncture.

I really do like the 1.5 degree for round nosed bullets though!

All the best,

kev
 
Kevin
The PTG Myers reamer have a 1.5 degree leade as you stated, It has spiral flutes, and no build in stop, but I do have and adjustable stop on it, so I can change the amount of engraving. Right now the barrel in question shows .115" from the face of the cone to the inner face of the rim with the Lapua round nose, and .090" with the Eley EPS bullet. As I stated before, it shoots the Lapua great.
I also have two other reamers, PTG for the LILJA tight bore barrels with a 2 degree leade, they have a build in stop, and are the ones that I used for the Silhouette rifles that I have re-barreled with LILJA barrels, which by the way, are winning Nationals, and State championships. Must of them use SK Standard Plus ammo. but the Eley still shoots great on them.
Do you think that the 2 groove barrel is more sensitive to the amount of engraving in the bullet versus the 6 grooves ?
I also tried a Rock Creek barrel 4 grooves, and encounter the same problem with the EPS bullets, I went ahead and run the Lilja reamer with the 2 degree leade, and it started shooting bug holes.
I am tempted to either go another .030" deeper on the existing chamber, or take a chance, and run the Lilja reamer thru it with a .216" bushing. The flyers that I am getting now are driving me crazy, I do not thrust the gun as is for serious competition.
What do you recommend ?
I can always just shoot Lapua ammo. on it, but I still think that it should be able to handle both brands competitive.
Evelio
PS did you ever work for NOV.???
 
Kevin
I was just thinking about the previous posting, and remember that when slugging the 2 groove barrel it took a lot more pressure to push the slug than it did with a 6 groove barrel, and it makes sense, since there is a lot more lead being displaced in the 2 groove.
Even not being official, my understanding is that the average speed in the Lapua ammo. is around 1072 and I have been shooting the ELY anywhere from 1054 to 1061, maybe I should try something over 1070 which I think I do have some Tenex at 1078. I will try it next week.
Evelio.
 
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