6mmBR giving me fits

[FrankG]

Frank I am glad you commented here .

I just seen this post/thread.

I don’t check out every thread on every forum. Some I frequent more than others but just don’t have that kind of time.

As a tip to everyone....if you ever have a issue...doesn’t matter if it’s the barrel, action, stock, scope, bullets, powder etc....yes it’s cool to check out this or that forum and talk to buddies to try and find a quick fix/solution but at times you should contact the manufacturer first or even the gunsmith first.

Later, Frank

 

[STOMP442]

STOMP442, Give me a call bud! Let’s figure this thing out!

Or give me a phone number to try and call you at.

If you have the s/n of the barrel give it to me when you call. It’s nice to have for reference if anything. If you don’t have it....when and where did you get the blank from if not from us directly?

Later, Frank
Bartlein Barrels

Frank shooting you a PM now.

 

[FrankG]

I am also glad you chimed in, I’ve given thought to a 7.5 twist for a build and just wasn’t sure.
Thanks
J

I’m running a 1-7 twist on a 6BRA and it’s a laser beam. 105’s, 107smk and 110 Hornday’s have all been hammers.

Also had a 6x47 Lapua in a 7.5 twist and it shot fine. Gun would actually hold 1/3moa at a 1k.

Another thing to think about is the chamber reamer that was used and how the barrel was chambered.

Customer sent in a 6.5 caliber rifle that he had a gunsmith build for him. Only has a couple of hundred or so rounds on it and couldn’t get it to shoot. So he called us thinking it was the barrel. Sent it in along with his reamer that the gunsmith used. Reamer had all kind of build up on it and the shoulder and throat was all torn. Barrel never had a chance from day one.

Later, Frank

 

[BIG D]

It can be a lot of things...

Tried different scope....so lets rule that out.

Bedding?

Crown damage?

Cleaning damage?

Yes can be barrel.

Yes can be ammo/loads. Very good friend and shooter and customer of mine just a few months ago thru out over $2k worth of powder that was bad. It’s a long story. We also have some powder at the shop that Mark uses for his bench guns. Opened up a brand new jug (older lot) and used it one time. Went to use it a couple of months later and it’s junk and cannot be used.

Firing pin spring is a good one to check along with the sear pin etc...inside the bolt shroud. We’ve seen issues with the firing pin and that pin dragging inside the bolt shroud not to mention burrs inside the bolt body from when the bolt was made. That burr inside the body will cause the firing pin to drag as well and cause ignition issues. We’ve seen these issues not just with factory actions but with custom actions as well.

That’s just some food for thought.

Later, Frank

Excellent advice.

 

[cmillard]

Wow
Great information, quick question- is there anytime when a bullet is over stabilized ?


thanks again

I think “overstabilization” is a myth. However, I have had projectiles turn into a cloud of smoke upon exit from a barrel and never make it to a 25 yard target (52 Sierra out of a 7” twist M4). I couldn’t figure out why I was not hitting target until I had a coworker shoot it as I watched from the side

 

[FrankG]

Wow
Great information, quick question- is there anytime when a bullet is over stabilized ?


thanks again

I’ll say not really but over spinning can cause poor quality bullets to amplify accuracy issues. So it’s a combination of things and or poor quality components.

I just posted about this in another thread a couple of weeks ago so I’ll make a long story short.

.223 Colt AR15A2 with factory 1-7 twist barrel. During testing the 69gr SMK would shoot into 3/4” groups at 100 yards. Shot some USA 55gr ball ammo thru it during the same range session. 2 out of 5 would go thru the target sideways. Perfect keyholes. Went home and checked everything out. Cannot find anything wrong. Loaded up some more 69SMK as well as some Hornady 52gr HPBT match bullets. Back out shooting and started with the 69gr SMK and back to shooting 3/4” groups. Tried the 55gr ball ammo and yep bullets again go thru target sideways. Go to the 52 Hornady’s and they shot 3/4” groups as well with no bullets going thru the target sideways.

Those 52 and even the 55’s will stabilize in a 14 twist barrel. The difference was the quality of the bullets and also the ammo. The crappier the bullet and or if the ammo has a lot of loaded run out the really fast twist will amplify the premature wobble of the bullet.

So I think quality of the bullet and ammunition makes a huge difference.

Later, Frank

 

[FrankG]

I think “overstabilization” is a myth. However, I have had projectiles turn into a cloud of smoke upon exit from a barrel and never make it to a 25 yard target (52 Sierra out of a 7” twist M4). I couldn’t figure out why I was not hitting target until I had a coworker shoot it as I watched from the side

It could’ve been possibly a combination of (I’m kinda guessing here) that the 52 Sierra has a thinner jacket and possibly something wrong with the barrel. Damage from when it was made? Damage from cleaning or to the crown and or how many rounds on the barrel? A barrel with a lot of rounds on it the throat gets rougher over time and will beat the bullets up more and cause issues like this in conjunction with a faster twist rate it was tearing the bullet a part.

 

[TAJ45]

A.) Don’t start pounding slugs down it!
B.) Doubt it is larger at the muzzle the way we make the barrels. Possible yes. I’ll throw Murphy’s law in here.

Frank - glad to have your knowledgeable input. Kind of a welcomed straight from horses mouth.
Re blunderbuss bores, doesnt that occur during lapping, application of compound and amount of time spent at the section?
I have never lapped a bbl or anything long but have some shop time on a Sunnen. But that was "several" years back.

Re tho problem of OP, I'm at 'replace f p spring and check for obstruction. Have read here of a gun immediately being cured.

 

[FrankG]

Frank - glad to have your knowledgeable input. Kind of a welcomed straight from horses mouth.
Re blunderbuss bores, doesnt that occur during lapping, application of compound and amount of time spent at the section?
I have never lapped a bbl or anything long but have some shop time on a Sunnen. But that was "several" years back.

Re tho problem of OP, I'm at 'replace f p spring and check for obstruction. Have read here of a gun immediately being cured.

Bell mouthing either on the breech end and or the muzzle end. Yes it can be from lapping or what I will say is over lapping. Lapping is meant as final polish and even though you will typically remove about a .0001" out of the barrel it shouldn't be done to achieve proper bore size. When you do this you are over lapping the bore of the barrel and you start effecting bore uniformity.

Also if the barrel has a lot of residual stress in the blank either from the type of manufacturing process you can end up with bore uniformity problems and or a thing of just threading the muzzle can cause the bore of the barrel to go sour.

Us doing single point cut rifling we don't induce any stress into the blank so for the bore to go sour on us is virtually non existent. Murphy's law....anything can happen but odds are against it.

The way some shooters clean the barrels can wreck/bell mouth the bores of the barrels as well.

Had one guy just a short time ago wreck 3 barrels in like 6 months. He was using an abrasive cleaner and a brush and the last barrel only had 110 rounds on it and he polished a full .001" out of the bore and groove! Not to mention started creating gouges in the bore of the barrel.

 

[C. Nichols]

did you bed the barrel and the lug? if so remove the bedding under the barrel and free float. May want to remove off the front of the lug. In my experience small contour barrels dont like bedding. Some like to be touched at the front of the forend but not in the back. I have seen many guns go from shooting a pattern to a ragged hole by floating it from action out. Just my 2 cents.

Chris

 

[FrankG]

Talked to STOMP442. He has a couple of things he wants to try as of yet. I told him either way keep me posted and if not working to send it in so I can take a look at it.

 

[cmillard]

It could’ve been possibly a combination of (I’m kinda guessing here) that the 52 Sierra has a thinner jacket and possibly something wrong with the barrel. Damage from when it was made? Damage from cleaning or to the crown and or how many rounds on the barrel? A barrel with a lot of rounds on it the throat gets rougher over time and will beat the bullets up more and cause issues like this in conjunction with a faster twist rate it was tearing the bullet a part.

Sorry, I feel like I am hijacking. That m4 barrel had maybe less than a 1000 rounds down the tube. I think those 52 match bullets are thin skinned if I’m not mistaken which would lead to failure

 

[Drop Port]

I friend has the same problem with his Bartlein 6.5-4s - all custom Gradous. No matter what bullet, or depth, or powder combo it is a 3/4" rifle at best.

Mine has a Bartlein as well but it's sub half" at 100Y.

Friend is ordering a 7mm barrel and going 7SAUM.

Who diagnosed your friends problem and what was the outcome? You just threw out two very reputable names. I have a Gradous built 6.5 on a Bartlein barrel and it is one of the finest shooting rifle I've ever owned. I know if I could only get 3/4 MOA out of it after trying everything my first call would be to Robert and he would gladly trouble shoot it if need be. As in this thread a lot of the good suggestions are among a few of the many other things it could be.

 

[FrankG]

Sorry, I feel like I am hijacking. That m4 barrel had maybe less than a 1000 rounds down the tube. I think those 52 match bullets are thin skinned if I’m not mistaken which would lead to failure

No sweat on the hi jack!

 

[Ccrider]

or a thing of just threading the muzzle can cause the bore of the barrel to go sour.

As I was reading this thread, this came to mind. My smith told me the same thing a few weeks ago when he threaded a barrel for a tuner. He left a very small space in case he needed to recut. He also said that he has seen where very small restrictions at the muzzle could cause problems.

He is not a benchrest guy but seems to be pretty smart.

 

[TAJ45]

Iirc, I've read Bill Calfee saying threading the muzzle can blossom the bore by .0001"

 

[FrankG]

Iirc, I've read Bill Calfee saying threading the muzzle can blossom the bore by .0001"

This effects button rifled barrels. Not cut rifled barrels.

We’ve turned 2.250” od test barrels down to a 5/8 muzzle thread for suppressor testing and didn’t lose a single one.

 

[TAJ45]

That is one ten thousandth of an inch!

Blossom!

Most people can't even measure that small.

That it is.......targets may tell that tale.
Measuring tenths? Deltronic pin gages

 

[blvedere]

Haven't read all the posts, but I had a barrel that would not do what I thought it should and had the barrel crown redone and helped quit a bit.

 

[FrankG]

Haven't read all the posts, but I had a barrel that would not do what I thought it should and had the barrel crown redone and helped quit a bit.

Stomp442 and I talked about the crown. He is going to double check it the best he can.