100 fps MV increase on annealing?

[Alex Wheeler]

Bore scope died and I haven't replaced it yet. lands were a bit tight. I had to find a .2358 bushing. Cleaning it seems to have a routine amount of fouling. thanks.

I think I'll go back to .237 barrels.

--Jerry

Is it a Brux? Thats the bushing they usually take...

 

[carlsbad]

yep

 

[mikecr]

While partial neck down sizing only(and no expansion), annealing never increases neck tension, but reduces it.
If the necks were FL sized, especially if including a donut, then a big variance could have been brought into tension.
IMO, it would take a combination of things to cause 100fps change. Something else..

 

[lawrence97]

I've never experienced such a velocity increase from annealing by itself. If the barrel is newer with a low round count it's probably speeding up on you if it now has between 100-200 rds.

Or, you may have a carbon ring built up which will definitely give you an unpredictable boost in velocity. I have had weird velocity jumps like you mention due to a carbon ring and it took some elbow grease, lots of solvent, brushing, patching and polishing with jb or iosso.

 

[carlsbad]

Well, reduced load over a grain and got about 40 fps reduction in velocity. Still too fast. I just ordered a new borescope to look for a carbon ring.

Thanks everyone for your help.

--Jerry

 

[dminn1]

Well, reduced load over a grain and got about 40 fps reduction in velocity. Still too fast. I just ordered a new borescope to look for a carbon ring.

Thanks everyone for your help.

--Jerry

I had a similar experience with increased velocity this weekend in a GAP 6.5 4S shooting 61g of H-1000 under a 140g Berger Hybrid. Loads assembled one day before shooting this weekend started exhibiting signs of high pressure so we hooked up the Magnetospeed chrono, and sure enough velocity had jumped 35 fps from previous session. We had some of the same 61g loads that were loaded 1 month ago so shot them over the chronograph and they gave identical readings to what they did 1 month ago with no pressure signs. All components were the same in both sessions including brass, primers, and powder from the same lot. All case prep was identical. When we got back to the shop we pulled down a sample from each loading session and the charge weights were both spot on according to the Sartorius scale.

My question is could this be due to the moisture content of the H-1000 powder. It has been extremely dry in our area over the last few months and I seem to remember reading the moisture content of powders does have and effect on there burn rate. Just wanted to throw this out there to get some feedback from anyone who may have had a similar experience.

 

[MislMan]

I am fairly new to handloading (2 years) and very much a neophyte to the hands-on process of many of the case preparation operations. However, I was wondering if maybe using the AMP annealer (induction) vs. flame annealing could be a contributor in this instance. Maybe the process provides a differing level of consistency for neck tension and case/chamber sealing. Also, any chance temperature of ammo could be a player? Early morning cool/cold vs. afternoon heat or direct sunlight. Powder used maybe affected more by temperature differences between shooting periods.

 

[carlsbad]

MislMan,
Good suggestion about the temp of the ammo.

Coincidentally, I went back and reviewed the history of this barrel since I chambered it and found a detail that I had missed.

In early Oct, at 3000 fps, the barrel shot great. I shot 46/50 at our monthly varmint match, and the 4 I missed were poor wind reads.

The next time I shot it, it started at 3000 fps and crept up to 3060 at the end of the match. It was a horrible match. My target puller was incompetent and I was struggling to get a score. It was hot and sunny out and I attributed the increase in velocity to the powder heating up and planned to being shade to the next match at this location. I also shot a lot of rounds trying to get zeroed with bad feedback from the pits. Hope I didn't melt the throat....but I think I just started to build up carbon.

The next time I shot it was the post annealing session that I reported above where the velocity went to 3100. My normal range location is cool and shady so the ammo heat isn't a problem. In retrospect, I see that the velocity was already trending up indicating the likely buildup of a carbon ring.

Yesterday, I noted much more sooting of the outside of the neck than normal.

I will probably find the answer when my new borescope gets here.

--Jerry

 

[Nomad47]

MislMan,
Good suggestion about the temp of the ammo.

Coincidentally, I went back and reviewed the history of this barrel since I chambered it and found a detail that I had missed.

In early Oct, at 3000 fps, the barrel shot great. I shot 46/50 at our monthly varmint match, and the 4 I missed were poor wind reads.

The next time I shot it, it started at 3000 fps and crept up to 3060 at the end of the match. It was a horrible match. My target puller was incompetent and I was struggling to get a score. It was hot and sunny out and I attributed the increase in velocity to the powder heating up and planned to being shade to the next match at this location. I also shot a lot of rounds trying to get zeroed with bad feedback from the pits. Hope I didn't melt the throat....but I think I just started to build up carbon.

The next time I shot it was the post annealing session that I reported above where the velocity went to 3100. My normal range location is cool and shady so the ammo heat isn't a problem. In retrospect, I see that the velocity was already trending up indicating the likely buildup of a carbon ring.

Yesterday, I noted much more sooting of the outside of the neck than normal.

I will probably find the answer when my new borescope gets here.

--Jerry

Bet you find a carbon ring.

I shot a local competition a couple years and a had a Magnetospeed attached for the entire competition. Velocity went up over 50 fps over the course of 36 rounds. I was stumped. But Preacher told me to look for a carbon ring. He was right.

 

[carlsbad]

Well. Borecam came and found severe cracking in the throat. Some carbon in the neck area but no real ring. I guess I'll trace this back to the first relay of a 1000 yd match I shot when my pit man gave me bad dope and had me chasing ghosts. Probably shot 40-50 rounds in that 22 min...

Tomorrow I'll set it back, rechamber, drop 2-3 grains of powder and keep the MV below 3000. Gotta manage heat better.

--Jerry

 

[jlow]

Well. Borecam came and found severe cracking in the throat. Some carbon in the neck area but no real ring. I guess I'll trace this back to the first relay of a 1000 yd match I shot when my pit man gave me bad dope and had me chasing ghosts. Probably shot 40-50 rounds in that 22 min...

Tomorrow I'll set it back, rechamber, drop 2-3 grains of powder and keep the MV below 3000. Gotta manage heat better.

--Jerry

Glad you figured it out! This is the hard thing about reloading for precision, everything "looks the same" but the unfortunately truth is there are buckets that we cannot see or sometimes control that affects how the thing shoots.