Load for new GM barrel

[kelvinator]

I've never been happy with the 1-48 twist of the factory barrel on my .50cal TC Rennegade so I recently purchased a drop in Green Mountain barrel.
It's a 32" 1-70 twist for patched round balls.
My question is where should I start with...
#1- patch thickness
#2- lube
#3- ball diameter
#4- powder charge

Anyone been down this road?
I'm thinking (and hoping) the GM barrel will be a HUGE improvment for patched round balls and will just need some fine tune on the powder charge.
If it matters, I'll be mostly hunting Texas whitetails within 125 yards.

Thanks, Kel

 

[ohio ramrod]

All rifles have a prefered load. But I suggest starting at .495 ball, .015 patch lubed with lard/beeswax or any nonpetroliumj oil, leather over powder wad, and 45 grain FFF . Work your powder charge up by five grain increments untill you find the best groups. (not exceding 90 grain). You may vary your ball size ,patch thickness, or lube as well but change only one variable at a time! :hmm: :hmm:

 

[necchi]

Good advise above.
Justa heads-up, mine didn't really start to get really nice groups till I had around 150 rounds down the tube.
Those 150 gave me plenty of time to experiment with the PRB variables.
There are many opinions about break in, but mine is that there is a break in period with these barrels, and my prefered method is to shoot'm in.

 

[kelvinator]

Thanks all. Ohio ramrod, just a question and please excuse my lack of knowledge. What is this "leather over powder wad" thing about ? Thats something I'm not familiar with, except for shotgun ? And FFF, the instructions that came with the barrel said use only FF or equiv. Guess I should be inquiring about break-in procedures as well.
Thanks again.

 

[ohio ramrod]

I use a leather wad between lubed patches and the powder to prevent the lube from soaking into the powder as well as to protect the patch. A folded over dry cloth patch will do the same thing. I prefer FFF because it burns cleaner ( for me at least ) and you can reduce your charge by approximately 10%. Thus saving on powder which is my number one expense when shooting. If you find your patches are shredded you can speed up the breakin process by using some rubbing coumpound ( not grinding coumpound which is courser ) on a cleaning patch or bore brush and giving the bore about ten good strokes. :hmm:

 

[ebiggs1]

I don’t’ use wads of any kind when I am just plinking or target shooting. I never noticed any improvement in accuracy and I shoot quickly enough the powder doesn’t get contaminated with lube. I do use a cardboard wad for hunting when the gun may be loaded for some length of time. I think it good insurance.
I shoot 70 grs of fffg GOEX with a .490 rb and a .018 pillow patch with either Bore Butter or olive oil. The GM 1:70 50 cal barrel is fantastic.

 

[roundball]

I've never been happy with the 1-48 twist of the factory barrel on my .50cal TC Rennegade so I recently purchased a drop in Green Mountain barrel.
It's a 32" 1-70 twist for patched round balls.
My question is where should I start with...
#1- patch thickness
#2- lube
#3- ball diameter
#4- powder charge

Anyone been down this road?
I'm thinking (and hoping) the GM barrel will be a HUGE improvment for patched round balls and will just need some fine tune on the powder charge.
If it matters, I'll be mostly hunting Texas whitetails within 125 yards.

Thanks, Kel

My loads are based on a .010" under bore size ball, using thick patches as they carry more lube, are more forgiving of variances in ball diameter because the material can compress, and more material is wedged into the gooves for improved gripping/rotation from the rifling.

PLINKING / TARGETS at 25-50 yards
50grns Goex 3F
.018" precut/prelubed pillow ticking
.490" ball (Hornady, Speer, or cast)

DEER HUNTING
90grns Goex 3f
Oxyoke .50cal prelubed wool wad
.018" precut/prelubed pillow ticking
.490" ball (Hornady, Speer, or cast)

I don't need an over powder wad to protect the powder from the lube I use, as Natural Lube 1000 doesn't affect powder.
I do use an over powder wad with large powder charge deer hunting rifle loads to provide better gas sealing and act as a firewall to protect the patch.

 

[Greenmtnboy]

Thanks all. Ohio ramrod, just a question and please excuse my lack of knowledge. What is this "leather over powder wad" thing about ? Thats something I'm not familiar with, except for shotgun ? And FFF, the instructions that came with the barrel said use only FF or equiv. Guess I should be inquiring about break-in procedures as well.
Thanks again.

Hey buddy,
I shoot several of Greenmtnbarrels from 36 cal to 54 and get MOA(one inch groups) at 100 yrds with all of them.
Here is how do it, you do it this way and your gun WILL! shoot MOA I promise.
First get Neco lapping compound(on line)
Lapp your barrel by putting lapping compound on a shooting patch .018(start with 220 grit).
start a ball and patch with compound on it and run it to the breach.
Put a ball puller on your 7/16 ranger rod start it into the ball and saw back and forth hitting the front of the barrel the most maby 40 times.Patch clean your barrel between Lapping with Hoppies # 9 to get all lapping residue out.
Do this three times for every grit, takes three hours.
Your barrel is now lapped in and ready to shoot.
Unless you got a rough barrel and if you did check now before you do all that work.
GMB have gone down hill in the last two years but I heard they are getting their crap back together.
If your barrel is very rough, SEND IT BACK!
OK now it's patch time.I don't give a hoot as to what every body else says After thousands of rounds through my competition rifles I have settled on two patches and ball combo's that will give you MOA.
Go to wall mart with your Calipers and get .030 and .028 canvas at the sewing dept.
The .030 is tan the .028 is white, it also comes in a couple different colors but mainly white.
Use this patch with a .010 under ball(what cal are you shooting?) and you will get great accuracy.
Wet lube
This is what you will use to get your gun most center at 50 yrds.
I use Lehigh lube when I can find it but I found six parts water one part Ballistol(from midway) and one part Murphy oil gets me as good accuracy.
For fine rifle tuning wile using a wet patch I swab between shots for consistency.
I wring most all moisture out of my wet patch before loading.
You can get MOA with a wet patch but for serious accuracy I use a Greased patch(elk tallow,Marmot oil) for hunting and a dry patch for bench rest work.
Dry patch.
Get Dutch Schultz's book on dry patch shooting.
It's the bible on dry patch(on line).
I can't go in to that much detail here.
Any way that will get you started.
Greenmtnbarrels are some of the most accurate I have ever shot including their fast twist conical barrels.
If you are shooting a 40 cal or 36 cal use fffG and a .020 canvas patch from Texas patching(on line) and a .005 thousands under size ball.

I use ffg for 45 cal and above.

NEVER use a over powder wad in you GMB your accuracy will go south.
I spent a whole winter trying to squeeze more accuracy out of my barrels and one thing I tried was a over powder wad, they don't work.

Here are a couple 100 yrd targest
one is a 40 cal, it was the last day I was siting it in.
first three were to the right, then I did a slight site ajustment and I setteled down to shoot two groups of five using the .020 texas patch.

The next is my standard 54 cal load for all three of my 54s with GMB

 

[Greenmtnboy]

If some ol fart had taught me this from the begining it would have saved me years of R.D. in partaining to Green mtn barrels.
hope it helps you out.
:hatsoff:

 

[paulvallandigham]

OP wads, and fillers serve as "Firewalls", to keep your patches from burning or tearing in the bore, from hot gases getting to them. It is sometimes necessary to use an OP wad with a given combination of ball diameter, and groove depth, because you can't use a thick enough patch fabric to reach down into and fill the grooves tightly with that given ball/bore combination. A Groove diameter( or slightly larger) Over Powder wad will fill the grooves, and will insure you don't get gas blow-by. ( Hot gases blowing through the deep grooves of the rifling, cutting and tearing, and burning the patch, and cutting or melting the lead ball in the barrel. )

Learn to recover and READ your spent patches after each shot- when developing your target and hunting loads. The patch tells you everything about what is going on in the barrel.

Most of us try using both 2Fg and 3Fg powder loads in our .50 caliber rifles, because the barrels often( not always) show a preference for one powder over the other. I used to believe that you could find a good powder load with both powders, if you worked at it.-- UNTIL my good friend Don- a long time gun builder, and gunsmith-- could simply NOT find a load that worked in his new .62 caliber rifle using 2Fg powder. Someone else( boy am I glad of that) suggested trying 3Fg, and after a lot of argument, he did. He found a very accurate load within a half hour.

He was dumbfounded, and so were the rest of us. I was there and I, along with half a dozen other members of the club, examined every one of his spent patches, discussed bore diameter( He had his calipers at the range) groove depth, ROT, ball diameters, patch thicknesses. The patches indicated that he was using the right diameter ball, the correct thickness of patch material, and the right lube on the patch. We all watched his cleaning procedure, and it was fine. We didn't have chronographs back then, so we lacked the benefit of using that diagnostic tool to find a load. Go figure.

If you have a chronograph, or can borrow one, it will help you immensely shorten the time it takes to find an accurate load with any brand of powder, or with any granular size. But, don't ever forget the importance of reading your spent patches. :thumbsup:

As for using or not using an OP wad to improve accuracy, my experience is different than that of Greenmountainboy. In my GM barrel, using an OP wad improved the burning of my 2Fg powder charge, reducing the amount of fouling in the bore after the shot. It also increases the velocity, raises the point of impact, GIVES tighter groups, and a lower Standard Deviation in Velocity( SDV).

But, this is ONE barrel, in one caliber( .50) with One Rate of Twist(ROT-1:48"). II won't attempt to speak for other barrels. With each new barrel, its my practice to test each with and without an OP wad, to see what happens. Its just something I do, just as I try both 2Fg and 3Fg powders.

In my shotguns, I am now going to add testing Fg powder along with 2Fg, and 3Fg powders, both with RB loads, and with shot, to see if I get better patterns.

I suspect that the lower pressure, and slower burn rate of Fg powder might deform the pellets less, and give me better patterns. But, for now that is just a working hypothesis. If I have to use substantially more Fg powder to achieve the same velocities as I get using 2Fg powders, without much gain in pattern density, or small size, I will end the experiment.

So, join the fun. If you learn something at the range, please share it with us. :v :thumbsup:

 

[kelvinator]

Whew...lots of great info to ponder. Thanks all.
I do have a chronograph and plan to use it. What is it I should be looking for with the velocities?
Least variation from round to round?
Thanks again

 

[OB OBrien]

First get Neco lapping compound(on line)
Lapp your barrel by putting lapping compound on a shooting patch .018(start with 220 grit).

Quote edited by OB.

Greenmtnboy; I recently got a 50 cal GM barreI with a 1 in 70 twist for PRBs. Have coned it and put about 50 rounds down the tube. Was in the process of finding the load as per the Dutch shultz method. Have some valve lapping compound. Its a grease mixed, silicone carbide with coarse and fine grit compounds.

Will this work as a substitute for the NECO lapping compound?

Thanks OB

 

[paulvallandigham]

Altho there is some disagreement about the correlation between a low SDV and small groups, I find in my experiments that there is a high degree of correlation between the two issues. So, yes, look for the lowest Standard deviation in velocity. Some chronographs will actually calculate that for you after a series of shots. My Chrony does not do so, so I have to do it on paper.

 

[Greenmtnboy]

First get Neco lapping compound(on line)
Lapp your barrel by putting lapping compound on a shooting patch .018(start with 220 grit).

Quote edited by OB.

Greenmtnboy; I recently got a 50 cal GM barreI with a 1 in 70 twist for PRBs. Have coned it and put about 50 rounds down the tube. Was in the process of finding the load as per the Dutch shultz method. Have some valve lapping compound. Its a grease mixed, silicone carbide with coarse and fine grit compounds.

Will this work as a substitute for the NECO lapping compound?

Thanks OB

Valve grinding compound may be to aggressive.
Neco compound starts at 220 grit.
I have used valve grinding compound in extream situations but you must lapp with a finer grit afterwards, even the fine valve grinding grit I have found to be very aggressive.

 

[Greenmtnboy]

This is correct with most production barrels with shallow grooves but not the 1 in 70, 12 thousand deep grooves of Greenmtnbarrels.
Thats why I use a thick patch, to fill grooves and to take heavy hunting loads without tearing.

[But, this is ONE barrel, in one caliber( .50) with One Rate of Twist(ROT-1:48").

Also you will find the 1 in 48 GMB to have shallow grooves to accomidate a conicle bullet. most 1 in 48 GMB seem to like a .018 patch which may be to thin with a heavy hunting load in a large cal.

:thumbsup:

 

[Greenmtnboy]

Whew...lots of great info to ponder. Thanks all.
I do have a chronograph and plan to use it. What is it I should be looking for with the velocities?
Least variation from round to round?
Thanks again

Here again you haven't told us what cal you are shooting.I take it you replaced you're old barrel with the same 50 cal slow twist barrel.
Using the patch and ball combo above in a 36 inch GMB of 54 cal with 100 grns of FFG Goex express I chrono 1800 fps with about 12 fps deviation.
My 50 with 90 grns FFG
My 45 with 80 grns FFG
Gives me about the same fps all tho my 45 is closer to 2,000 fps.
Same deviation

 

[kelvinator]

Yes, it's a .50cal.
I replaced the TC 26" 1-48 twist with the GM 32" 1-70 twist.

 

[Greenmtnboy]

There is absoulty no reason not to use 100 grns of FFG Goex to stoke that barrel up for hunting.
I do all my starting loads, to settle down and get used to the rifle and bench at a moderate load, 70 grns for my 50, it's also how many grns I shoot my 50 for off hand comps.
I use 90 grns of FFG Goex express and am flat at 100 yrds and 1.5 inches high at 50 yrds.
You will find that those GMB shoot quite well with many different FFG powder loads. Some of mine like hot loads like my 45 Leman I shoot comps with.
My groups really tightened up at 70 grns and I get One hole 50 yrd five shot groups with 80 grns.
If you get a nice smooth GMB with no cutting marks you will have a shooter!
Yrs ago I put a new GMB barrel on a Traditions production rifle in 50 cal and that gun was mirror bright diden't even lapp it.
Now my wife ownes it and has not lost a compitition with the boys in two yrs.I haven't beat her in three and usually post second or third.
I practice a bit but I lay it on having a dead shootin' gun.
Off hand you should be shooting center at 50 yrds will be the same at 25. If you shoot off hand at 100 yrds increase your charge by ten grains and that should put you on at 100 yrds.
I started doing that when I went to fix sites only shoots and works dead nuts with GMB.

 

[Pete Gaimari]

This is a very interesting thread to me, because i'm looking at a Renegade with the same GM barrel. It's been shot a lot, so I don't think the barrel needs to be broke in. I hope anyway.

I respect Greenmtnboy a lot, so i'll listen to what he says.

Hopefully, you will too.

 

[Greenmtnboy]

Morning capper :hatsoff:
Is that rifle for sale at American hunting and fishing?
Make sure you shine a bore light down the barrel.
Did ya get that 20 below weather we are over here.