Lands evaluation

[BBob]

I do understand that part of it, thats why its so hard to imagine how the reamer would leave only 2 lands behind...

If it's not headed or guided in some way down the center of the hole it's not going to cut everything evenly around the existing hole...it's going to cut everything offset the amount the reamer is off the center of the hole. In other words it cuts offset to one side cutting more off one side than the other leaving lands shorter on one side and longer on the other. It's as if you drilled a new hole slightly offset from the original hole. To add: If the reamer is offset by only a few thousands the throat would be obviously visibly offset with shorter and longer lands. It needs to be guided in a pretty precise manner.

When a land might only be .003" of an inch tall you can easily see how little the reamer can be off and cause concentric throat issues.

Typical 6mm bbl: .243" groove, .237" bore.
.243-.237=.006, .006/2= .003

 

[Koda_]

If it's not headed or guided in some way down the center of the hole it's not going to cut everything evenly around the existing hole...it's going to cut everything offset the amount the reamer is off the center of the hole. In other words it cuts offset to one side cutting more off one side than the other leaving lands shorter on one side and longer on the other. It's as if you drilled a new hole slightly offset from the original hole. To add: If the reamer is offset by only a few thousands the throat would be obviously visibly offset with shorter and longer lands. It needs to be guided in a pretty precise manner.

When a land might only be .003" of an inch tall you can easily see how little the reamer can be off and cause concentric throat issues.

Typical 6mm bbl: .243" groove, .237" bore.
.243-.237=.006, .006/2= .003

Its making more sense, appreciated the explanation. I felt the same way as the OP when I found mine this way, lucky for me it was just a range toy and not a nice hunting rifle like the OPs. I kept mine but should have sent it back....

I have had more than my fair share of warranty issues with guns though, and bad enough it can ruin the attachment to the gun purchase and use. All in the last few years alone too. Quality has gone downhill the last 4 years significantly.

 

[deer_hunter132]

Its making more sense, appreciated the explanation. I felt the same way as the OP when I found mine this way, lucky for me it was just a range toy and not a nice hunting rifle like the OPs. I kept mine but should have sent it back....

I have had more than my fair share of warranty issues with guns though, and bad enough it can ruin the attachment to the gun purchase and use. All in the last few years alone too. Quality has gone downhill the last 4 years significantly.

i have two BCA wylde rifles. im going to look at them soon. BTW, they have been great when there is an issue. Im sending back the .308 upper because 147gr nato ammo is 3moa. 180gr federal was much better but i didnt keep track. they replaced a 6.5cm barrel and bolt already. terrible accuracy and the bolt pin hole was too big which causes pierced primers, which is what happened.

 

[wind gypsy]

It's extremely difficult for lots of 223 chambers to not show some kind of land in the freebore because the freebore diameter is the same or very close to groove dimension.

223 freebore is 0.224", i think wylde is 0.2242". Groove depth is typically spec'd at 0.224". which means any tiny bit of being non-concentric results in one side of the freebore being shallower than the lands and thus lands would be visible through the freebore. I think 556 nato freebore is 0.226" and thus should be less common to see lands in the freebore.

 

[sdupontjr]

Yes it is a factory Browning A bolt with the boss. What's also weird, is he said that he put a friend's suppressor on it and it shot tighter than it ever had. But I wasn't there to see what the grouping was, he's okay with minute of deer as long as he's able to kill deer which somehow he's always able to pull it off.

I have the same rifle. When playing with a load with a BOSS on it, you have many variables to deal with and can deal with. The reason it shot tighter groups with the suppressor on it is because the weight of the suppressor was in the "best" location for the tuning weight on the end of the barrel. Mine is a early 1990's Browning Abolt II Medallion 7mag with BOSS, the 1st year browning introduced them. I would assume you have a 9.5 twist, as mine does.

Mine also never shot lower grain bullets worth a crap no matter what Boss setting. I always shot 150 - 162's. Being he has a Browning, he is not limited to Saami specs on the 7mag. Saami spec on COAL is 3.290", I run my 162 eld-m at 3.415". The maximum allowable COAL by modifying the Mag is 3.714", at least in my gun. So don't limit yourself to 120 grain bullets if they won't shoot. Take the mag apart and use a small chainsaw file to make grooves to allow the tip of the bullet to clear. The action on the Browning 7mag is slightly longer than the mag so even if you take off to much, it will still clear the action and cycle like butter.


There is a metal rivet that keeps the aluminum in place in the middle. Don't remove that rivet, nor file it down. I worked up a load using R-P brass, CCI-250, H-1000, 162 eld-m seated at 3.415" Boss setting on 2.0 and shoots .311 moa at 100 yards.

When dealing with the Boss, only mess with one variable at a time or you will chase your tail. So since you have the Boss, utilize it. Its nothing more than a tuning weight which is why the suppressor helped his load. So pick a bullet / powder combination, load up some charge weights and go to range. Shoot looking for pressure or velocity node. Thats it, don't worry about groups or any of that. once you have settled on a combo, load some up and go back to range.

-Put Boss on setting 2.0, shoot 3 for group
-Put on setting 3.0, shoot 3 for group. If group is getting tighter, go to setting 4.0. If group opens up, go backwards, to setting 1.0.
-Continue doing this until you get the desired groups you want.
-If group from 2.0 and 3.0 are the same, then work on 1/2 increments.
-Depending on how 1 hole group you want, work in 1/10ths, but bring lots of ammo.

Most who do load development, develop a load for their particular rifle. You have the ability to not worry about groups when load developing, but rather a velocity node, then tune that velocity node to your barrel.

So even if you lands are buggered up, you may still be able to get some life out of the barrel by tuning a load to it.

 

[deer_hunter132]

I have the same rifle. When playing with a load with a BOSS on it, you have many variables to deal with and can deal with. The reason it shot tighter groups with the suppressor on it is because the weight of the suppressor was in the "best" location for the tuning weight on the end of the barrel. Mine is a early 1990's Browning Abolt II Medallion 7mag with BOSS, the 1st year browning introduced them. I would assume you have a 9.5 twist, as mine does.

Mine also never shot lower grain bullets worth a crap no matter what Boss setting. I always shot 150 - 162's. Being he has a Browning, he is not limited to Saami specs on the 7mag. Saami spec on COAL is 3.290", I run my 162 eld-m at 3.415". The maximum allowable COAL by modifying the Mag is 3.714", at least in my gun. So don't limit yourself to 120 grain bullets if they won't shoot. Take the mag apart and use a small chainsaw file to make grooves to allow the tip of the bullet to clear. The action on the Browning 7mag is slightly longer than the mag so even if you take off to much, it will still clear the action and cycle like butter.
View attachment 704130View attachment 704129

There is a metal rivet that keeps the aluminum in place in the middle. Don't remove that rivet, nor file it down. I worked up a load using R-P brass, CCI-250, H-1000, 162 eld-m seated at 3.415" Boss setting on 2.0 and shoots .311 moa at 100 yards.

When dealing with the Boss, only mess with one variable at a time or you will chase your tail. So since you have the Boss, utilize it. Its nothing more than a tuning weight which is why the suppressor helped his load. So pick a bullet / powder combination, load up some charge weights and go to range. Shoot looking for pressure or velocity node. Thats it, don't worry about groups or any of that. once you have settled on a combo, load some up and go back to range.

-Put Boss on setting 2.0, shoot 3 for group
-Put on setting 3.0, shoot 3 for group. If group is getting tighter, go to setting 4.0. If group opens up, go backwards, to setting 1.0.
-Continue doing this until you get the desired groups you want.
-If group from 2.0 and 3.0 are the same, then work on 1/2 increments.
-Depending on how 1 hole group you want, work in 1/10ths, but bring lots of ammo.

Most who do load development, develop a load for their particular rifle. You have the ability to not worry about groups when load developing, but rather a velocity node, then tune that velocity node to your barrel.

So even if you lands are buggered up, you may still be able to get some life out of the barrel by tuning a load to it.

Good info. I did find jam and was able to load it i think .020 from jam and shot that, .030 from jam was mag length iirc.
He's messed with the boss before, and where he has it was the best he was able to do. I'm trying to remember but I believe another can we tried on it it shot worse. He's a bit discouraged. He's got a Remington 243 my sister used that he'll hunt with if Browning doesn't have the gun back in time for deer season.

 

[deer_hunter132]

@Koda_ here is my BCA wylde

 

[Wapiti1]

Why is there lands in the freebore at all though? It shouldnt be there at all according to Sammi spec.
Even if it was from cleaning, how would you get four land " rifling grooves" to wear evenly in distance from the chamber?

Lands in the freebore isn't uncommon. Min spec reamer, Max spec bore get you there pretty easily. I've seen a lot of throat areas where the lands didn't get cleaned out completely in a variety of chambers. And you assume they used a SAAMI spec for all of this. It was made in Japan. There is no requirement to use SAAMI anything.

It's pretty easy to get extremely even wear from cleaning. Typically, a person uses the same cleaning stand for the rifle, the same rod, and the same arm to drive the rod from the same standing or sitting position behind the rifle. They drive the rod the same every stroke and the wear ends up in one spot. I've see it many times, mostly, on very old rifles that just don't shoot well anymore. I've also seen it on benchrest guns where they didn't have a good fitting bore guide. Although benchrest guys are complaining about a 1/16" larger group. Most of the time the wear is at the 6 to 9 o'clock position because right handed shooters load the rod down and to the left during the stroke.

It could be a crooked chamber. A lathe chambered barrel can't produce such a chamber, but that isn't the only method used for chambering at the factory. A setup where the reamer is driven can, and many factories use non-piloted reamers.

I've looked at a lot of barrels. This one makes me want more information than the video shows.

Jeremy

 

[deer_hunter132]

Lands in the freebore isn't uncommon. Min spec reamer, Max spec bore get you there pretty easily. I've seen a lot of throat areas where the lands didn't get cleaned out completely in a variety of chambers. And you assume they used a SAAMI spec for all of this. It was made in Japan. There is no requirement to use SAAMI anything.

It's pretty easy to get extremely even wear from cleaning. Typically, a person uses the same cleaning stand for the rifle, the same rod, and the same arm to drive the rod from the same standing or sitting position behind the rifle. They drive the rod the same every stroke and the wear ends up in one spot. I've see it many times, mostly, on very old rifles that just don't shoot well anymore. I've also seen it on benchrest guns where they didn't have a good fitting bore guide. Although benchrest guys are complaining about a 1/16" larger group. Most of the time the wear is at the 6 to 9 o'clock position because right handed shooters load the rod down and to the left during the stroke.

It could be a crooked chamber. A lathe chambered barrel can't produce such a chamber, but that isn't the only method used for chambering at the factory. A setup where the reamer is driven can, and many factories use non-piloted reamers.

I've looked at a lot of barrels. This one makes me want more information than the video shows.

Jeremy

10-4. if i have this rifle back in my hands as is, i will get some more pics/video, just so everyone can learn.