David Tubb Final Finish Bullets

[RDG]

Well, I shot my rifle for accuracy. Five shots 2" at 100 yds. a nice cluster no flyers...It also hurt my accuracy. It was shooing around an inch.
This gun shot 3200 fps. when it was new. And I clean my barrels reguarly.
I think the bullets ruined my barrel. I have used them before with good results.
I did exactly as the instructions "said to do". clean thoroughly after every ten shots. It looked to me as if the first 40 bullets were the same grit. I even looked at them under a magnifying glass, and couln't tell any difference. The other bullets I used you could tell the difference by simply looking at them.
I'm calling to company who made them and see what they say.
Thanks! For your guys input.

RDG

 

[keithcatfish]

I used only 25 (5 of each grit) in my .308 and they moved the throat forward .03". My accuracy is the same as before FF but I had to increase my OAL to compensate for the longer throat. Work up a new load and all should be well.

 

[Jeff In TX]

I used only 25 (5 of each grit) in my .308 and they moved the throat forward .03". My accuracy is the same as before FF but I had to increase my OAL to compensate for the longer throat. Work up a new load and all should be well.

Catfish,

You did mean .003 and not .03?

But I agree with you. Remeasure/reload and give it another shot. I still think you improved your barrel or the barrel was toast before you started.

Keep us up to date!

 

[keithcatfish]

I mean .03". OAL distance to the lands with a 168SMK went from 2.865 to 2.894.

 

[zupatun]

I used FF on my Tikka 308 Varmint. Went out and it is down about 75fps from the drops I'm seeing out at 300 yds compared to before. However, it is MUCH easier to clean and soooo smooth. Can't say I dislike the results.

Matt Roth

 

[goodgrouper]

I used FF on my Tikka 308 Varmint. Went out and it is down about 75fps from the drops I'm seeing out at 300 yds compared to before. However, it is MUCH easier to clean and soooo smooth. Can't say I dislike the results.

Matt Roth

I would venture to say that you lost more speed than that but your bc increased. Might be worth chronongraphing to make sure especially if your making charts for long range shooting.

 

[Jeff In TX]

I would venture to say that you lost more speed than that but your bc increased.

Goodgrouper,

I'm not busting your chops here, really I'm not but I've got understand your logic on this one.

By firelapping the barrel how much of a BC increase do you think he achived? Even an increase or decrease of 100 points on the BC isn't going to have any significant effect on his muzzel velocity. By removing a carbon build up in the throat any change in BC (if any) would be extremly minute, I doubt it would change less than a point.

Here's what I've seen through a bore scope when I'm looking at barrels when I visit speedy's shop. The barrels with the biggest carbon build up in the throat area are from folks who don't use brushes on a regular basis. The tell speedy they use solvents and patches to clean after shooting. Not saying this is wrong, just an observation.

More than likely Tubb's FF removed the carbon build up and polished his throat decreasing the pressure.

Now the decrease in accuracy. More than likely he pushed his OAL out especially if he used 50 rounds or more of FF. I'm sure that throat area and first few inches are as smooth as a baby's behind. He's going to have to re-measure his OAL and adjust for the longer OAL.

What we don't know is what kind of condition the barrel was in prior to him using the FF. How many rounds had the barrel seen? It there was a large carbon build up in the throat, it probably means a lot. Lots of unknown factors to consider.

Worst case, he could always have the barrel set back and re-chambered which would give him a fresh starting point. Wouldn't cost that much.

The best advice I can offer is for him to take it to someone who has a bore scope. Borescopes don't lie.

 

[goodgrouper]

Jeff,

I have fired the FF down three of my custom barrels that had severe throat erosion and were taking forever to clean. They also were so rough that they degraded the bc of my bullet (when checked across two chronos 300 feet apart) to a significant degree. After using the kit, I had to increase the powder charge by as much as 3 grains to get the speed back to normal levels where the gun liked it. Then I checked the bc of the bullet in the same manner and found that it was actually higher than the listed bc and higher than the bc I found when the barrel was new.

In other words, if I had kept using the chart from the original bc findings or from the degraded bc findings and pumped the speed back up to normal, the POI would have been high on every shot.

In chronographing many barrels after using FF, there USUALLY is more than a 75 fps loss. It's more along the lines of 150 fps or more. So, while the bc change is slight and the speed loss is not too big, they still must be factored in to achieve first round hits at long range.

My point in all this was that trying to figure out what happened with your external ballistics solely based on what drops you are seeing without chronographing or checking bc is not going to give you an accurate chart.


And one other thing I should point out here: Sometimes with some barrels, after you finish shooting the Tubb's kit, you might not get any marks on the bullet from the lands because it gets so smooth. So a guy might think he can no longer touch the riflings but he actually still is. Best way to check is the old magic marker on the bullet method.

 

[Rymart]

I've firelapped two rifles with the Tubbs FF bullets. I was happy with the results on both lappings. The first became much easier to clean and was much more predictable on the CCB shots. The other went from shooting 2-3 inch groups to shooting 0.75 to 1.0 inch groups, but was only slightly easier to clean. Following both lappings, I had to treat the rifle just like I had put a new barrel on it. That meant re-measuring OAL and working up/tuning a load from the beginning (tuning the powder charge weight and the 'jump-to-the-lands') as well as re-tuning the drop charts for the new load. To me that was a given, but well worth it.

 

[Jeff In TX]

Jeff,

I have fired the FF down three of my custom barrels that had severe throat erosion and were taking forever to clean. They also were so rough that they degraded the bc of my bullet (when checked across two chronos 300 feet apart) to a significant degree. After using the kit, I had to increase the powder charge by as much as 3 grains to get the speed back to normal levels where the gun liked it. Then I checked the bc of the bullet in the same manner and found that it was actually higher than the listed bc and higher than the bc I found when the barrel was new. .

Goodgrouper,

Most folks aren't as anal as you and I when it comes to figuring out the true BC. But having said that he was talking about a 200 fps drop in velocityat the muzzle. A change of 100+/- points in BC isn't going to effect muzzle velocity enough that you could measure it. Agreed, down range results would be off.

I'm curious to know how much improvement in BC you get with before/after FF. Unless the barrel was a total mess I still can't see the BC changing all that much, really not more than a point or two and I think that would be stretch... but I've learned in my job to never say never cause I see some strang things that shouldn't happen but do.

 

[zupatun]

I would venture to say that you lost more speed than that but your bc increased. Might be worth chronongraphing to make sure especially if your making charts for long range shooting.

Chrono is on my X-mas list and a must for getting my handloads tweaked in the future as well as increasing my accuracy. You may be right, I guess my main point is that it used to take me so long to get all the blue out of my barrel and now it takes about 1/3 of the work it did before. I like that tradeoff up front. I don't think it hurt my accuracy at all either.

Matt

 

[specweldtom]

Jeff; every time I log on to this site, I learn something. I'm one of those people who don't brush, mostly for fear of eroding the crown. I make a single point Winchester match gun type crown; straight across and then straight out. This leaves a very sharp, very true corner at the end of the bore, but I theorize that brushing might wallow it out. Shooting doesn't appear to hurt it.

Carbon buildup seems to me could be much more harmful than degrading the crown. I got to think about this.

Thanks for the heads-up, Tom

 

[Jeff In TX]

Jeff; every time I log on to this site, I learn something. I'm one of those people who don't brush, mostly for fear of eroding the crown. I make a single point Winchester match gun type crown; straight across and then straight out. This leaves a very sharp, very true corner at the end of the bore, but I theorize that brushing might wallow it out. Shooting doesn't appear to hurt it.

Carbon buildup seems to me could be much more harmful than degrading the crown. I got to think about this.

Thanks for the heads-up, Tom

Tom,

Like you, I'm concerned about my crown so I switched to nylon brushes and they seem to do a very good job for me. After shooting I use wipe out accelerator and patch the gunk out of the barrel followed by Wipeout foam bore cleaner and let it sit. Depending on the gun after a set time I'll scrub the barrel with a nylon bore brush for 15 or 20 passes and patch it out clean. A single patch with Kroil followed by 2 or 3 dry patches...Done! This works really well for me and when I do get a chance to look through a bore scope I'm usually very pleased.

Every once in a while, maybe once a year or so I use Isso bore paste with my nylon bore brush.

 

[old_heli_logger]

According to the FF instructions, you're supposed to use all 50 of these bullets...are some of you suggesting to use less? Maybe half that many? The instructions also say to clean every 5 shots...would you suggest to clean between each shot?

My Browning A-bolt LH Medalion 7mm RM is a copper factory. I also think I might have a carbon build-up problem...what's the best way to remove the carbon? Nylon brush w/ Isso paste? Brake-clean?

Thanks for everyone's help!!