Advanced Marksmanship Barrel speed up?

[dzander]

I've been shooting 41.2 grains of reloader 16 in my 6.5 creedmoor lapua cases and Berger 140 g hybrids.
when I developed a load I was averaging 2772 FPS. I went and shot a group of 13 rounds over the Chrono and I've picked up 53 fps , 2825. The 26" Kreiger Barrel now has 474 rounds thru it. Groups oped up from .40" to about 1.1" roughly.
Should I decrease my powder charge to get back to the 2772 fps I had when it shot good? 41g to 41.4 g of reloader 16 only gave me a 6 fps spread when I developed the load so I settled at 41.2. any body see this before or have any ideas where to go from here?

 

[lash]

It is not uncommon at all for a barrel to speed up after it has done rounds on it. Typically this will happen somewhere more around 100 rounds though. A couple other things can affect velocity though and could also be contributing factors. A change in the lot or canister of powder being used or a change in the ambient temperature that you are shooting can speed up or slow down a load.

In your case, since you just noticed it, instead of backing off the charge, just do a short redevelopment around your current load and also test a couple different seating depths. Typically I would just do a simple seating depth test on the existing load.

 

[DellaDog]

picked up 53 fps

Just be careful, the first sign of a carbon ring is an unexplained, sudden increase in speed. Followed shortly by a pierced primer.
(Ask me how I know)

 

[lash]

Just be careful, the first sign of a carbon ring is an unexplained, sudden increase in speed.
(Ask me how I know)

True, true...

 

[dzander]

same 8# jug of reloader 16, temperature been within 10 degrees , same lot of bullets also.
I'll give it a good cleaning and repeat test see if its the same. Where does the carbon ring form?

 

[dimar1492]

same 8# jug of reloader 16, temperature been within 10 degrees , same lot of bullets also.
I'll give it a good cleaning and repeat test see if its the same. Where does the carbon ring form?

The carbon ring will form at the end of the neck in the chamber just before your freebore starts.

A few different ways to attack it, but I'll say that a light cleaning with most of the popular solvents usually doesn't do the job thoroughly.

 

[dzander]

How about a brush that would go in the neck area of the chamber with solvent rotate with a drill?

 

[Supersubes]

I shoot a 6 creed with a very mild load(115 at 2890 with RL16) Doing a bit of a test to see how long it lasts at that level. My barrel is still speeding up at 580 rounds, and Im continually backing off the charge to keep it there. That’s probably a drawback all by itself, but it been very linear. When it speeds up to 2925 or so, it opens up a bit. I could speed it up into the next node or back off, and I just choose to back it off because the throat shows zero wear.

 

[dimar1492]

Stick a CLR soaked patch in the neck and let it sit for 10 minutes or so. It will eat the carbon up pretty good and then a slightly oversized brush rotated in the neck should finish the job.

 

[Steel head]

Every one of my Shilen and Brux barrels has sped up.

 

[Scimitar]

How about a brush that would go in the neck area of the chamber with solvent rotate with a drill?

I would not do this sir. Very good way to damage your barrel. I would use solvent and bronze brush. if that doesn't get it, use the Kroil and JB Bore compound method.

 

[Shootnwrench]

Listen to the last everyday sniper podcast from the Berger No BS series. Powder moisture content is another variable to consider.

 

[Ledzep]

Typically, initial rounding of the sharp corners in the throat can account for some speed up (what most folks see in the first 100 rounds). Most of the time anything after that is related to fouling. I've done lots of long strings where I chrono every shot and see anywhere from 10 to 35 fps "walk" in the average MV over 50 rounds as the barrel fouls. It depends on the barrel/cartridge. The worst offender I've seen so far is a Savage 6.5 PRC that was not cleaned for ~150-200 rounds. It gained ~175fps and was blowing primers. Cleaned, it dropped back to sanity and pressure problems went away. It was .255/.262 land/groove diameter and pretty rough for bore finish. I've also seen barrels that are regularly cleaned every 5-20 rounds throughout their life with meticulous records kept that show almost no indication of MV speed up or slow down in their service life, which points more towards fouling being the primary driver for increases in velocity.

 

[morganlamprecht]

^^this

 

[Scimitar]

He's right. I had forgotten but I had a Savage barrel do this. They replaced it.

 

[MakeSawdust]

Typically, initial rounding of the sharp corners in the throat can account for some speed up (what most folks see in the first 100 rounds). Most of the time anything after that is related to fouling. I've done lots of long strings where I chrono every shot and see anywhere from 10 to 35 fps "walk" in the average MV over 50 rounds as the barrel fouls. It depends on the barrel/cartridge. The worst offender I've seen so far is a Savage 6.5 PRC that was not cleaned for ~150-200 rounds. It gained ~175fps and was blowing primers. Cleaned, it dropped back to sanity and pressure problems went away. It was .255/.262 land/groove diameter and pretty rough for bore finish. I've also seen barrels that are regularly cleaned every 5-20 rounds throughout their life with meticulous records kept that show almost no indication of MV speed up or slow down in their service life, which points more towards fouling being the primary driver for increases in velocity.

This bit me hard at the last 2 day match I shot. Fouling caused things to speed up about 40 fps. The close stuff lined up and the change was not noticeable. I had shot all the long stages on day one 1st thing and hit some targets I didn't think I would be able to hit. I finished with several closer positional stages. The first stage of day two was a troop line going to 1500ish yds. I hit the close target around 450 and the next target was around 880. I missed several shots over the top that I thought were likely wind errors. After finally seeing one go high I fixed it and hit my last shot before timing out. I used that shot to fix the velocity in the calculator and things started to hit again. I have noticed a couple of times that the velocity in the chrono was different with a bunch of rounds between cleaning, but I always thought it was some inconsistency in my reloading. You guys have confirmed what I was beginning to suspect.

Does either one of you have a good method of tracking and compensating for this? Just try to interpolate the best I can?

 

[dimar1492]

I usually considered ideal match condition of my bore to be something like this.

I would clean the barrel and make sure there was no carbon ring building up like mentioned above. Then, foul with 30 to 40 rounds while confirming a perfect Zero. I found this level of "seasoning" to be ideal.

While the gun would usually return to zero and start grouping well within the first few rounds. I saw that sometimes it would be another 20 or 30 before velocity SD went back down. Also noticed that the more you wear the barrel, the more "seasoning" they usually like.

This should get you through a match plus a practice session or two with consistent velocities before repeating the process.

I found this to be much more predictable than shooting "until groups open up". The whole time somebody is shooting and waiting for their groups to go to shit, there is still the possibility excessive fouling causing pressure spikes. Which can lead to velocity fluctuations and even zero shifts due to node changes.

 

[MakeSawdust]

This is very similar to what I do, and I still see things speeding up gradually. I clean every 120-250 rds. The carbon ring and throat are inspected with a borescope to insure there is no buildup of fouling there after cleaning. The only variation might be the number of rounds used to get a zero. I typically have 20-25 rds down a clean barrel before a match from confirming my 100 yd zero and shooting 10 over the magnetospeed.

 

[Ledzep]

What caliber are you shooting?

I've never tracked more than 100 rounds for velocity, so I don't have good data on velocity walk over something like a two-day match. I've noticed some slight changes and corrected for them by editing velocity in 4DoF.

 

[dimar1492]

That honestly sounds about ideal. And just to clarify, I'm not saying that I burn 40 rounds just to check zero. Just that once I have confirmed my SDs are where they need to be (20-30ish rounds depending), I'm using the last handful of rounds to confirm zero.

 

[morganlamprecht]

i dont have a method for tracking it as much as im fairly confident in keeping it where i want it

using a labradar makes it easy to track speeds and POI on every shot without any outside influence

i know on any of my barrels...if i wet patch after each range trip, until most of the "black" comes out...usually takes 4-6 patches for good barrels...then follow up with some dry patches...if i go shoot that barrel again, the first shot will be 40-50 fps slow, the 2nd will be close to normal, then from 3+ its back to same...POI is close enough that shooting anything over 1/2-3/4 moa sized targets, it doesnt matter much unless shooting far enough that speed difference will cause issues...with one of my hunting rifles i cleaned and fired a cold/clean bore 5 days in a row @ a 8" plate at 400 and was easily inside of it every day....the newer/less wear on the barrels, the more consistent the first shots and groups are after being patched ie; barrels with less than 500 rounds on them will shoot similar groups clean or fouled, high round count barrels usually take longer to settle in group sizes...not anything wild, like 3+ moa, but my last 6creed i cleaned/shot had north of 1500 rounds on it and the first 12-15 rounds shot 3/4-1moa-ish, then it was back to stacking shots

for my hunting rifles that dont get shot much, i patch them out after shooting similar to above, then run a couple patches of graphite fluid like lock ease down the bore...then patch out with a couple dry patches...this takes away the first shots being slower in every barrel ive tried it in (5 total i think)

the easiest way i dealt with any fouling issues when shooting a bunch of matches was good cleaning of the chamber and bore before any 2 day or major match, then just shoot 10-20 to foul it in on range day or prior to the match...id shoot 1 day/clubs however if i was feeling lazy, but always made sure it was cleaned and ready for a 2 day...id have no issue cleaning between days 1 and 2 since i know how my barrels behave, but i never did it because i didnt want to pack my cleaning kit stuff around

the last 2 day i shot and tracked my speed close...was NM last year...i went in with a recently cleaned/fouled barrel and my speeds were avg 2885 (w/ 130s)...after the range day + match approx 250 rounds later, i was avg 2910....after a good cleaning, things were back to 2880-2890 range

ive actually seen guys who didnt clean their barrel for 2000+ rounds lose something like 100 fps after a good cleaning

 

[MakeSawdust]

Seems reasonable. I clean really well every 200 rounds or so. After the first 15 or so, even on a worn barrel the sd will be around 10, but the velocity between shot 25 and shot 200 has been 20-40 fps faster. On day one I was probably around shots 75 or 80 after cleaning and was still hitting at 1100 on 1.5-2 moa targets (surprised me, I usually have issues). The next day, I had the long range stage where I was a couple tenths high at 880 or thereabouts and .4 or .5 high at 1350ish. I changed the calculator to put me where I needed to be on that 1350 target and everything lined up. I even hit some other targets that were out past 1300 yrds. It never really mattered at 500 and in and was definitely inside the targets at 600 and in. It took a 40 fps correction from my chronograph velocity before the match to get things to line up. I never confirmed with a chronograph after the match, but I can't figure out any other reason why my dope that was good one day was off the next. Especially when the closer positional stuff was still good. I even tried running a tenth low on a couple 400-500 yd stages because I thought maybe my zero was high and all my hits were at the bottom of the target. I suppose I just need to add 10 fps for every 50 shots or so after cleaning and play that way until I can get a labradar and track it.

 

[n00g7]

Shots 1-20 I ran up to 43.9gr H4350 on my 25 creedmoor, 2996fps.

Charge for same velocity dropped .5 gr from 1-20 to 21-40, then another .7 by 100.

Shots 101-110 ran 3010 @ 42.7.

2nd powder lot for shots 111-120 ran 2996 @ 42.7.

Hoping it’s done moving now.

 

[morganlamprecht]

Seems reasonable. I clean really well every 200 rounds or so. After the first 15 or so, even on a worn barrel the sd will be around 10, but the velocity between shot 25 and shot 200 has been 20-40 fps faster. On day one I was probably around shots 75 or 80 after cleaning and was still hitting at 1100 on 1.5-2 moa targets (surprised me, I usually have issues). The next day, I had the long range stage where I was a couple tenths high at 880 or thereabouts and .4 or .5 high at 1350ish. I changed the calculator to put me where I needed to be on that 1350 target and everything lined up. I even hit some other targets that were out past 1300 yrds. It never really mattered at 500 and in and was definitely inside the targets at 600 and in. It took a 40 fps correction from my chronograph velocity before the match to get things to line up. I never confirmed with a chronograph after the match, but I can't figure out any other reason why my dope that was good one day was off the next. Especially when the closer positional stuff was still good. I even tried running a tenth low on a couple 400-500 yd stages because I thought maybe my zero was high and all my hits were at the bottom of the target. I suppose I just need to add 10 fps for every 50 shots or so after cleaning and play that way until I can get a labradar and track it.

could be speed related, but dope also isnt a 100% on every time thing either...the local place i shoot depending on lighting/clouds/mirage on certain days, it can move your dope .2-.4 @ 800 yds...those things cant really be corrected for by the calculator

in a match, the for sure way to do it is adjust on the fly to get hits, but i always try to back track and re-verify post match if i have anything funky go on...sometimes you can compare with entire squads having similar misses, but you never really know whos zero/dope was spot on to begin with either so not always completely reliable

 

[morganlamprecht]

Shots 1-20 I ran up to 43.9gr H4350 on my 25 creedmoor, 2996fps.

Charge for same velocity dropped .5 gr from 1-20 to 21-40, then another .7 by 100.

Shots 101-110 ran 3010 @ 42.7.

2nd powder lot for shots 111-120 ran 2996 @ 42.7.

Hoping it’s done moving now.

the last barrel i checked pretty much 100% of the way, was a 6creed...i loaded the same load and shot it from shot 1 to 1200...rough #s from memory but theyre close...

1-25ish started ~2960 fps
25-100: 2975-3000 fps
by 125: 3020 fps

it stayed at 3020 until ~700-750 rounds

750-900 (in a match with high round count stages): post match it was ~2960 fps again

at 1200 rounds when i pulled it to set back it was 2940 fps

 

[dimar1492]

the last barrel i checked pretty much 100% of the way, was a 6creed...i loaded the same load and shot it from shot 1 to 1200...rough #s from memory but theyre close...

1-25ish started ~2960 fps
25-100: 2975-3000 fps
by 125: 3020 fps

it stayed at 3020 until ~700-750 rounds

750-900 (in a match with high round count stages): post match it was ~2960 fps again

at 1200 rounds when i pulled it to set back it was 2940 fps

The last few 6XC barrels I burned through followed a similar pattern. Except they lasted closer to 1500-1700 rounds before pulling them. Had one Hawk Hill pipe that started to crap out after 700 rounds. Was hemorrhaging speed. By 950 rounds I was 150 fps slower than original and this was after I had added nearly a full grain of powder.

 

[morganlamprecht]

yea that barrel was a really good one actually...when i pulled it at 1200 it was still shooting 1/2moa easily, but we wanted to do some stuff to it and use it as a "test" barrel for some things...it got set back 2" and has ~1600 rounds on it now, still shooting well...its had about 8 different powder/bullet load combos pumped thru it since the set back testing/comparing various things

 

[n00g7]

the last barrel i checked pretty much 100% of the way, was a 6creed...i loaded the same load and shot it from shot 1 to 1200...rough #s from memory but theyre close...

1-25ish started ~2960 fps
25-100: 2975-3000 fps
by 125: 3020 fps

it stayed at 3020 until ~700-750 rounds

750-900 (in a match with high round count stages): post match it was ~2960 fps again

at 1200 rounds when i pulled it to set back it was 2940 fps

If I do the same charge (rather than velocity) for this barrel (25 cal benchmark), it gained approx 100fps over the first 100 rounds.

1-16(#7,8): 2902 @ 42.7
(Cleaned)
17-32(#17,18): 2950 @ 43
(Cleaned)
33-50(#49,50): 2956 @ 42.6
(Cleaned)
51-70 (#63-66): 2972 @ 42.7
(Cleaned)
71-100 (#83-87): 3006 @ 42.7
(No Cleaning)
101-120: 3010 @ 42.7

 

[lash]

This is all very good info. Thanks for posting up your experiences for us!

 

[AnimalMother224]

How about a brush that would go in the neck area of the chamber with solvent rotate with a drill?

this was the only way I could get mine out. this was after 400rnds of AmericanGunner with simple light cleanings after every 100 with standard solvent.

IF this happens again im going to plug the muzzle and filter it up with CLR and let it soak .. that shit is AMAZING on carbon.

 

[StrayDog]

What's the clean up routine after letting a CLR soaked patch sit on the carbon ring? Dry patch it out, or do you neutralize it with something else first, etc.?
I'm about to step into my first Creedmoor rifle and this is all very much appreciated info!

 

[dimar1492]

What's the clean up routine after letting a CLR soaked patch sit on the carbon ring? Dry patch it out, or do you neutralize it with something else first, etc.?
I'm about to step into my first Creedmoor rifle and this is all very much appreciated info!

I usually run a couple patches soaked with Kroil and then dry patch it out. Isopropyl alcohol is fine too. I prefer the Kroil because it's also a penetrant and may help dislodge remaining residue.

 

[AnimalMother224]

What's the clean up routine after letting a CLR soaked patch sit on the carbon ring? Dry patch it out, or do you neutralize it with something else first, etc.?
I'm about to step into my first Creedmoor rifle and this is all very much appreciated info!

garden hose... lol.. im not kidding

 

[Perpetual Student]

I'm wondering the role ambient temperature changes might be playing when checking muzzle velocities, and over the course of a match?

Starting a match in the cool morning hours, then temps peaking in the afternoon, there might be a swing of 20 degrees or so. Seems that would account for some variation in muzzle velocity?

Recording ambient temperatures when you check muzzle velocity might be helpful. A 90 degree day will yield faster muzzle velocities than on a 50 degree day. This variation in ambient temperatures is also a good reason to not push chamber pressures too high. What's borderline at 50 degrees could be a problem at 90 degrees.

 

[AnimalMother224]

I'm wondering the role ambient temperature changes might be playing when checking muzzle velocities, and over the course of a match?

Starting a match in the cool morning hours, then temps peaking in the afternoon, there might be a swing of 20 degrees or so. Seems that would account for some variation in muzzle velocity?

Recording ambient temperatures when you check muzzle velocity might be helpful. A 90 degree day will yield faster muzzle velocities than on a 50 degree day. This variation in ambient temperatures is also a good reason to not push chamber pressures too high. What's borderline at 50 degrees could be a problem at 90 degrees.

Ive attempted to keep good track of MV and ambient temps and I haven't been able to see a linear line involved with that... the kestrel app has a nice section to record that information and its all over the place. including using the ever so amazing and near perfect H4350 /sarcasm

 

[dzander]

I did the CLR soak and cleaning .
At 182 rounds thru Barrel Velocity at 41.2 grains averaged 2778 FPS
Now at 547 rounds thru barrel is 2798 FPS at same charge,41.2 g
Now 40.5 g is giving me a average 2765 FPS. (5 shots)
my low was 2759 FPS and my high was 2775 FPS. 16 FPS total spread.
I didn't run the 40.5g when I tested at the 182 round mark.

 

[Brettdec]

I've experienced this with a few rifles and found carbon deposits and work hardening of the case neck to be the variables at fault. Ambient temperatures and powder sensitivity should also be considered if you haven't already.

The solution... A good bore scope and annealing method to keep things consistent. My experience has been that only the lead area needs much work on a high end barrel. Break free carbon cutter and a nylon brush rotated in the neck area with time for the solvent to work is the gentlest method I can come up with. Sometimes, if a stubborn spot appears and I'll resort to a little JB bore paste, which it very effective. The key is seeing what's going on in there.

I've done more damage with barrel soaking than brushing in my day.

At $50, a teslong bore scope is a no brainer.

While chasing accuracy, little mysteries can turn out to be quite expensive and time consuming. Bounce some photons off of it if you are interested in the actual status of your bore.

 

[dzander]

Or I could take it to my proctologist!
reloader 16 supposed to be very temperature stable. not that bid a difference in temperatures anyway.
all shot with new Lapua brass so that rules out the case necks I would think. Do you guys use a expanding mandrel to size your case neck I.D.'s? I'm not , just wondered as I notice different pressure sometimes when seating bullets.

 

[morganlamprecht]

the biggest difference in seating i can feel on a typical press comes from inside neck condition (dry, carbon'd up, stainless cleaned, polished, lubed, etc), regardless of size

ive compared it with a hydro seater as well

far as consistent seating pressure...if my brass is dirty (like mud/dirt), ill throw it in a the dry tumbler soon as i get home...then i size it, ive got both standard dies and bushing...the standard have the ball installed, the bushing do not...the bushing sized stuff i will run over an expander...then i wet tumble for 30-45 min and dry...chamfer the inside...run a nylon brush in the neck...its prepped to load

some of those steps can be cut out, but ive found that even changing the order can change things depending on the brass type used can cause issues...for example, i was wet tumbling after sizing, then drying and running the expander...with AMP annealed hornady brass, this worked fine, everything smooth...with AMP annealed Lapua brass, some of the brass seemed to want to stick/gall unless i put lube in the necks even with the expander being TiN coated...i could feel it seating bullets into this brass also...changing the order cleared up any issues and seating is butter smooth with any brass so i dont have to worry with it

ive done it as lazy as possible, from taking dirty fired brass, running thru a sizer and reloading it...to more in depth steps than above...i shoot mostly everything in field matches so my brass hits the dirt a lot...its easy to scratch up dies with sand and grit, ive put some gnarly grooves in dies before being lazy lol...above is an easy process for how i run it...its hassle free and the same over and over again

for new brass i always run it thru my normal sizing/loading steps like it was fired...especially lapua, since out of the box every lapua ive had had super tight necks and sticky from the annealing process

 

[Brettdec]

I did not use mandrels until having custom dies made recently. The guys at Forster made a good argument for the rationale.
I size down just enough that the mandrel expands the neck by only a few thousanths. My concerns of pulling the case out of concentricity and additional work hardening are (hopefully) lessened by this approach. The jury is still out. Not enough data yet.

Prior to that, I would turn my case necks just enough to true them. I would size without a mandrel, but would re-true after a few reloads to remove brass displaced from neck sizing.

It's a lot of work.

 

[AnimalMother224]

man. imagine all these troubles everyone is posting and then add them on to a MPA cut Xcal "match" chamber tighter than a bullfrogs asshole and try to load any respectable speed...

..welcome to my world. its almost made me quit the sport a few times. and its my first year!

 

[lash]

man. imagine all these troubles everyone is posting and then add them on to a MPA cut Xcal "match" chamber tighter than a bullfrogs asshole and try to load any respectable speed...

..welcome to my world. its almost made me quit the sport a few times. and its my first year!

I once had a smith cut my barrel with a match chamber without my direction. I shortly had him cut it as a more standard chamber. In field and PRs style shooting, I am looking for reliability and good mag feeding as much as accuracy. It might be different if I were shooting benchrest.