Borescope Surprise

[Oso]

Howa sent me a surprisingly nice one for $450.

This fall several Howa Mini's joined the family circle (6ARC & 6.5 Grendel). I hadn't even thought to look with the Borescope... Just the thought of it gives me heart palpitations. With exception of an issue that I can't identify, I'm leaning heavily toward "Ignorance in Bliss"

 

[Kracken McGraw]

This fall several Howa Mini's joined the family circle (6ARC & 6.5 Grendel). I hadn't even thought to look with the Borescope... Just the thought of it gives me heart palpitations. With exception of an issue that I can't identify, I'm leaning heavily toward "Ignorance in Bliss"

You will be pleasantly surprised when you do look.

 

[ebb]

Borescope Surprise??? A factory rifle with a poor barrel is hardly a surprise Although it should be. I feel your pain and long for the day when you buy a rifle and it produces that level of accuracy that the maker claimed.

 

[Oso]

Borescope Surprise??? A factory rifle with a poor barrel is hardly a surprise Although it should be. I feel your pain and long for the day when you buy a rifle and it produces that level of accuracy that the maker claimed.

I'm not surprised that a factory barrel is marginal quality / performance. I just have never put eyeballs on how bad it looked inside. My experience is the amount of work it takes to try to turn a pig's ear (factory barrel) into a silk purse (1/2 moa or better) is usually a loosing proposition. Nothing against factory rifles...

 

[ebb]

Kreiger and Bartlein make new barrels every day. I agree with you that trying to find a load to make a pigs ear into a silk purse is not as common or easy as most tend to believe. I wish that that looking at the bore could tell you one way or another, but way more knowledgeable barrel experts say looking is does not always tell the tale. I messed with a 223 for a year and could not get it to shoot, put 2 scopes on it with a hood scope checker and found out in 3 shots. My shooting buddy told me months ago it was the scope, and I told him it was brand new it had to be something else. I have something against factory rifles! Most need better barrels and scopes.

 

[William Vogel]

This gun was "like-new" with minimal round count. The "barely there" Remington factory finish had no wear marks from cycling the action or handling marks on the exterior of the rifle. The Yankee Hill Phantom QD mount (circa 2010-2015) didn't even have any carbon buildup from use with a suppressor.

The only mark on the bolt is result of the rear action screw being proud by 1/32". When inserting the bolt back into the receiver the front edge of the bolt face can make light contact with the top of the screw if the bolt rides up the the receiver tang before it is inserted into the action. Tomorrow, I plan to lightly touch/kiss the rear action screw against a diamond wheel.

The Speer 125gr TNT bullet is one of most accurate and reliable performers out of the 300BO. It is extremely easy and forgiving.... similar to 69gr SMK for 223. I will load up some 125gr SMK and see if this rifle likes them better.

I have an old Remington 700 Police 308 rifle that has terrible rust pits in the barrel that I found after I got the borescope. The rifle shoots 2.5 inch groups at 700 yards and through the same hole at 100 yards with 45.6 grains of IMR 4895 Lapua brass Hornady 168ELD and Federal 205 primers. I think you should give your barrel more load development time before throwing in the towel. My barrel looks horrible. I have a new Bartlein to replace it but I’m not touching the rifle because it’s that good now.

 

[ebb]

^^^^^^ They will all die if you shoot them enough. Having one waiting is the best way to make it last forever. Well maybe not, a good 30BR could outlive me at this point.

 

[Oso]

Range Update:
Loaded 2 sets of ammo using 1x fired cases thru rifle (only neck resized): 125gr TNT and 125gr SMK.
H110 charge weights from 19.0gr to 21.0gr in 0.5gr increments. 5 shot groups.

I was shooting off Bald Eagle Rest and rear bag. Weather was sunny, 60F and minimal wind.
100 yard groups (5-shot) tighten as velocity increased... went from 2.5" to 1.7"
Within several of the groups there were bullets touching and even through same hole...
Average velocity started at 2,252fps (19.0gr H110) to 2,401fps (21.0gr H110)

Time to spend some money for trigger upgrade. Maybe a Rise Armament Flat Blade (#1.5-#4 adjustable)
I am going to try this rifle on a bipod.

 

[M-61]

and through the same hole at 100 yards

That’s really impressive. A .000 group.

 

[Bill K]

So OSO, that new rifle just needed or needs a different load or two, from what worked in your others.
Not surprising really. And it does show, I would say, that even tho the new barrel looks rough, it will shoot nice groups. Keep us posted on further results and your enjoyment of this new toy.

 

[Oso]

That’s really impressive. A .000 group.

That is a couple of the shots within a 5 shot group... Not a "Zero"... just a couple of close buddies living within a 2" group. Good enough to kill a pig but not enough to satisfy my OCD

 

[M-61]

That is a couple of the shots within a 5 shot group... Not a "Zero"... just a couple of close buddies living within a 2" group. Good enough to kill a pig but not enough to satisfy my OCD

I thought you meant better than this:

 

[Oso]

Very nice. A couple of my other rifles shoot .1-.2, but none of those are sporting a 16" factory barrel.

 

[SS GO DEVIL]

H110 or Lil Gun under a nosler 125 ballistic tip has been excellent for me. Use the military cci primers. Work up load and I bet it shoots closer to expectations. Also remember that’s a fast twist for such a light bullet.

 

[SS GO DEVIL]

Another off chance would be firing pin spring. I always start there when diagnosing a rifle that won’t group.

 

[Oso]

Another off chance would be firing pin spring. I always start there when diagnosing a rifle that won’t group.

I have a soft spot for the 300BO, and lifetime supply of brass cases so hard to let it go. My approach to this rifle is "fun toy" that is mostly stock. I've been trying to avoid making major investments into this rifle that I may not keep.

As far as the ignition system, the factory firing pin hole is mass-production / oversized. As expected this is causing cratering around the edge of the firing pin indention (not the worst thing). The bigger issue is that the primer strikes are shifting between center and off-center. If I decide to keep this rifle then I may want to bush the firing pin. Changing the firing pin spring is an inexpensive upgrade.

 

[Oso]

Update:

The HS Precision stock is fully bedded including pillars. After upgrading the trigger with a TImney Hit, I tightened the action back in the stock to 65 lbs/inch. Everything is tight and fits well together. No obvious culprits.

I prepped a group of Gemtech cases (new) and trimmed to uniform length. Based on the powder charge (19.0gr - 21.0gr H110), I adjusted the bullet seating depth to approximate a +95% case fill. The TNT's canalure was outside of the case mouth. small sample groups (5 rounds) with SD ranging from mid 20's to 40 fps, ES was dismal approaching 75-100fps.

Rifle doesn't like shooting off a rest. Did better off the Green Caldwell bag and rear squeeze bag. Bringing out a bipod on the next range trip. See how SD/ES shrinks with 1x fired cases.

Before I started burning up better bullets, I wanted to get a baseline and sort out any obvious issues. I think we are there.