Loose bore = Less Velocity?

[Shane Lindsey]

Would JB bore paste smoothe this out? Or would it need lapped?

 

[FEENIX]

Was actually trying to leave that out, but it's a 338 Sherman. Using Peterson 280AI brass.

I agree with Lance's post below; he will not stir you wrong.

I take Sherman data with a grain of salt...and I have a BUNCH of Shermans. And a lot of the info on their spreadsheet was supplied by me. I have tested a couple of the first ever chambers. But I do my own testing. And I think I am pretty good at reading pressure signs and have very realistic expectations of where velocities should be. I would be researching .338-06AI recipes.

I don't always go with the conventional powders. There are more commonly used powders like BL-C2, Varget, H4350, RL17, but I wouldn't discount RL23, N560, maybe even N565.

Ed

 

[VinceMule]

JB does little with rough barrels, but it will clean them extremely well, especially the JB Bore Bright(Red). Iosso will also do a good job.

There is an expensive learning curve in learning to "lap" with Brownells 600 and 800-grit silicone carbide paste as it cuts steel FAST..

 

[MagnumManiac]

Would JB bore paste smoothe this out? Or would it need lapped?

If you look closely between pic no.1 and pic no.2, you can see I have already lightly lapped that barrel, I will use JB on it every time I clean it for about a dozen times. I can't complain, it was a customer return warranty and I got it for less than half price, a Win Model 70 EW Portuguese made rifle. It had crooked scope mount holes, so I drilled them to 8-40 and later found the rough bore, it shoots sub MoA with 225g Accubonds.

Cheers.

 

[Barehandlineman11]

You can buy some tubbs bullets and fire lap it

 

[Shane Lindsey]

You can buy some tubbs bullets and fire lap it

Thought about that too. Just concerned it would potentially make it worse. Any one used these before? I have seen mixed reviews.

 

[Barehandlineman11]

Ive used them on a christensen it helped it.

 

[Barehandlineman11]

Ive used a lot of jb paste too it helps as well.

 

[Radman]

Greetings,

I have a rifle that is a wildcat. I am not getting the velocities without pressure that others have seemed to get listed on here. Not even close.
I am curious if a "loose" bore would cause the lack of velocity? Meaning, I am using more powder to get the same velocities, but the bore is so loose that it just doesn't get it moving??? I have had a tight bore on a Christensen barrel that pressured fast, usually around start loads.

When I push a patch through, it is kind of loose compared to my other 338 barrel.

Anyone else have this before?

Just like in an engine: A worn cylinder & piston = blowby.

 

[FullCurl8]

Ive used a lot of jb paste too it helps as well.

If a guy had nothing but time, a JB paste true review would be interesting. This bad fouling bore in this post, 10 strokes with x amount of paste, with a certain jag and method. Clean and shout 5 over chrono and at paper.
Then 15 strokes etc.
My guesstimate is it takes an awful lot of abrasive paste and the results are a lack of uniformity, a smooth looking bore, that is inconsistent in most ways. I've lapped many barrels, to make good barrels great.
But you can't lap a *** barrel into much more than minute of deer.

 

[Barehandlineman11]

I only use it on a gun with minor imperfections not something that cant be fixed

 

[WiscGunner]

Rarely will they get 40 rounds through them before I clean them back to steel.

First off, in my experience you are leaving velocity on the table. 22" barrel compared to user supplied data on Sherman site with a 24" barrel will obviously be slower. Also in my experience fouled barrels are faster than clean to steel barrels. At least in the cartridges I have experience with the barrels speed up after 100-200rounds and when I eventually have to strip the barrel back to steel it will need some fouling again to speed back up.

I loaded to the length advertised and nada. Just decided to try the Hammers as they were less sensitive to jump so I could load mag length.

Are you loading to "length advertised" like a shot in the dark or are you loading to your rifle specs. Maybe I have interpreted this incorrectly from your text but other peoples load data is irrelevant to me for the most parts. Loading "factory" ammo and expecting"custom" results is not a recipe for success.

Are you doing velocity/pressure testing with virgin brass or brass fired to your chamber? Loose brass can show fake/early pressure signs from being slammed back into the bolt face.

Have you measured your Base to Ogive in the actual chamber of your rifle? If so, based on that measurement, what amount of jump are you loading/trying?

213 Hammer Hunter 2677 FPS with Varget.
175 Hammer 3065 FPS with CFE 223.
These are the only ones that shoot at least MOA. Both line up with Hodgdon's 338-06 data, towards the top. My velocity is a little slower due to 22" barrel length, but thought I would be gaining a little with the increase in case capacity.

Everything else I only did one round per charge weight for velocity/pressure. All were low before I got ejector print where I wouldn't go further. Backed off and just no accuracy, so moved on to another bullet.

These are where I had pressure, no accuracy.
250gr Hornady BTHP 2617 FPS with Staball 6.5 and 2601 FPS with H4350 (I don't think they make this anymore).
200gr Nosler BT 2867 FPS with Staball 6.5 (no longer made).
225gr Speer BTSP 2701 FPS Rl17.
250 Bergers was able to get to 60.3gr Rl17, but never clocked it as accuracy wasn't there so moved onto the ones above.

Not available anymore? Bullet or powder?


Forgive me if I have read your posts incorrectly, just seems to me the basic are being skipped to jump to some random numbers others have published.

 

[Shane Lindsey]

First off, in my experience you are leaving velocity on the table. 22" barrel compared to user supplied data on Sherman site with a 24" barrel will obviously be slower. Also in my experience fouled barrels are faster than clean to steel barrels. At least in the cartridges I have experience with the barrels speed up after 100-200rounds and when I eventually have to strip the barrel back to steel it will need some fouling again to speed back up.

Are you loading to "length advertised" like a shot in the dark or are you loading to your rifle specs. Maybe I have interpreted this incorrectly from your text but other peoples load data is irrelevant to me for the most parts. Loading "factory" ammo and expecting"custom" results is not a recipe for success.

Are you doing velocity/pressure testing with virgin brass or brass fired to your chamber? Loose brass can show fake/early pressure signs from being slammed back into the bolt face.

Have you measured your Base to Ogive in the actual chamber of your rifle? If so, based on that measurement, what amount of jump are you loading/trying?


Not available anymore? Bullet or powder?


Forgive me if I have read your posts incorrectly, just seems to me the basic are being skipped to jump to some random numbers others have published.

Pressure signs are pressure signs. Ejector print ( ), ejector swipe, flat/flowing primers. All there before I get close to what others have posted.

Length advertised is from the Sherman data. COAL 3.57" with a 250 Berger. I understand it is for a certain chamber but it was .010" off with a 250 Berger. Yes, I found the lands in my chamber and then backed off.

250gr Hornady and Nosler 200gr Ballistic Tips are no longer manufactured. I picked them up to fireform and break in the barrel.

No basics were left out. I didn't just arbitrarily load and shoot. As this is a wildcat with little data, I used other folks data combined with other 338-06 and 338-06AI data, backed off and loaded conservatively. I found the lands wuth every pill tried and established my jump accordingly. I just didn't get the velocity others were seeing.

 

[Shane Lindsey]

Follow up. I ran some JB paste through it and ran out for a quick range session.

Wet the bore with Eliminator
50 passes of JB gray with a patch over a bore brush
1 wet patch with Eliminator
100 JB gray with patch over a bore brush
1 wet patch with Eliminator
60 passes of JB red over patch and bore brush
1 wet patch Eliminator
100 passes of JB red over patch and bore brush.
Cleaned with wet patches and nylon brush to remove all remnants of JB paste.

Apparently I do not know how to clean a rifle. I'll take this for accuracy. Didn't chrono as I thought I was just going to see if there were improvements. I am still walking right up to pressure signs, but they are faint.

I quit while I was ahead.