+P Throating

[Dirtrax]

Larger bores realize a larger gain in velocity. As I understand it the material removed from the throat creates an improved heat sink. This extends throat life on some, but should not increase throat erosion on any cartridge. Fire cracking on my 7mm Practical has been minimal despite a 45 +/- fps gain. I also coat bullet and bore in hBN but had done so prior to Defensive Edge performing the work so it's apples and apples. This bbl is about done so Shawn will be getting a call soon!

 

[Nomosendero]

Good to know, thanks

 

[RUFFIAN R - NY]

AM READING PROS / CONS on this one ?????

 

[Tac-O]

Watched the video, but I'm not entirely sure what the modification is. Just increasing the land to land diameter in barrel where the bullet touches the lands?

 

[waveslayer]

This is a heated debate and has caused some very hurt feelings. PM if you really must know. But there is no pressure testing data from those guys making+P chamberings!!!! Show me the data...

The owner of Bartlien Barrels even chimed in and said, " stay away"

I wouldn't do it, yes you can get more velocity, but at what cost?

 

[jasent]

Watched the video, but I'm not entirely sure what the modification is. Just increasing the land to land diameter in barrel where the bullet touches the lands?

Slightly less slope where the lands start so engraving pressure is less spiked

 

[Dirtrax]

It is a patented process so I would not expect full disclosure. I'm guessing here but on the other end of the scale is the Hammer Bullets "Absolute" and CEB bore rider that accomplishes something similar with the exception of doing so with the bullet rather than the bore. The concept is to ease the transition resulting in lowered pressures. This requires increased powder charges resulting in increased velocity. I have no idea how this affects pressure nor do I care as long as my rifle and my face don't suffer the consequences. As with everything it remains incumbent upon the hand loader to read the signs and make wise (safe) choices.
As far as Bartlien Bbls opinions I cannot argue a vague reference. Truth is I couldn't argue anything barrel related with them, nor would I try. But given a propriety process they may not be in a position to promote it.

 

[cathead]

I have a 6.5 PRC plus p I'm shooting the 156 Berger's out of a 24 inch Bartlien carbon fiber barrel 61.5 grains H1000 at 3090 FPS accuracy is 1/4 to 3/8 MOA at 100 yards 1/2 MOA out to 1000

 

[Ucsdryder]

the 2 negatives I've heard are…

1. Accuracy
2. Barrel life

The problem is I don't think either are easily quantifiable due to all the factors that go into both. It would seem possible that accuracy COULD be negatively affected due to the bullet starting to spin slower, (less grooves at the start of the lands) and barrel life could be negatively affected for the same reasons. This is all assuming I understand it correctly.

 

[cathead]

I've had a 6.5 PRC and 7 WSM both have shot 1/2 out to 1000 yards speed in both increased about 100 FPS

 

[RUFFIAN R - NY]

all these new terms is a problem in itself ????????? Confusing YES

 

[Northkill]

Some seem to like it. I was about to try it but was counseled against it by a developer who played with the concept himself over the same time. From his perspective, guys were excited with the initial results - as was he. But accuracy life was short and they ended up giving up more than they gained in the end. I avoided the idea on that premise, so can't speak with personal authority. However, I've worked with Bartlein enough that I would give their take fair consideration at least. Barrels are expendable, so if you wanna give it a try, go for it. I'd love for someone to do a running post from start to finish (of barrel life) on this chambering/throat design with transparent reporting of effect and progress over time. Would need to have some pre+P data as a benchmark for comparison from the same rifle/barrel.

Edit:
Maybe the new 400 MOD harder barrels from Bartlein would be a better candidate for this..?

 

[RUFFIAN R - NY]

When Parker A built my AI 's he recut the throat made a little longer after first testing ( high psi ) came down and did pick up a few extra FPS .As for bbl life am still shooting but don't load hot and still holding zero along with all my Ackley AI. that he built.

 

[parshal]

I believe +P is some sort of bore rider throat where the throat diameter steps down by about .005" as it progresses. It's, basically, longer freebore but of two different diameters.

I had a bore rider throater made for 6.5. I ran it in a 6.5SS barrel I was getting ready to replace just to see what would happen. I lost about 70 fps, if I remember correctly, using ammo that was already loaded. I never did add powder to get it back up to speed and see how much further I could push it. But, it did as advertised which is reduce pressure.