Range Report 6.5 creedmor... After 575 rounds its slowing down. Normal??

[Aimsmall55]

Ok, I've got a ga Crusader 6.5 with a 27" 8.5 twist #7 bartlein. When I first was breaking it in I was picking up speed... A lot of speed. Started at 2760 and after 150 rounds I was at 2865-2880. Powder lot is the same , bullet lot .. Primer lot, case lot all the same. I've got a whole bucket of 1x fired brass because the new brass I think is comparable to Lapua as I don't have to prep at all and it just saves time not worrying with neck tension ect... Well I'm close to 600 rounds and the rifle is slowing down for some reason. All the loads are exactly the same. Load is 140 vld , fgm210m, 42.4 h4350, 2.140 to ogive. I shot threw my chrony today and average was 2796. It still shoots lights out but I'm merely curious, is this common??

 

[usafabrad]

Just spitballing, im thinking it might be several things:
1. Copper fouling buildup ( if you dont wipe copper out) could be tightening up your barrel.
2. Your scale might be drifting , causing you to measure out slightly lighter loads on average.
3. Shooting in colder conditions/seasonal variations. Colder powder/barrel can lead to a slight pressure difference (in theory)

Could be alot of things

 

[MTETM]

Chronograph...Hell... Are the come-ups the same?
I can't give you a straight answer, but I do know that over time, rounds fired, I increase the powder charge to maintain velocity...

Good Luck

 

[Aimsmall55]

Chronograph...Hell... Are the come-ups the same?
I can't give you a straight answer, but I do know that over time, rounds fired, I increase the powder charge to maintain velocity...

Good Luck

Come ups at 530 yards have changed + .5 moa

 

[Grand]

As throat erodes, pressure and velocity will drop. Have you adjusted your OAL?

 

[kurt]

different lot of powder?

 

[Aimsmall55]

As throat erodes, pressure and velocity will drop. Have you adjusted your OAL?

Yes, but in reverse. I actually found a sweet spot a little shorter than I was shooting. One would think this would give more velocity ?? It seems the more I jump em the better they shoot..... As to below. No powder is same lot. Bought 12 #'s when I got the rifle. I did check the throat erosion and it was not too terribly bad. I think I will just up my charge about .3 to .4 grains and I should be gtg

 

[OKbow87]

Moving the bullet away from the lands will decrease the spead.

 

[Aimsmall55]

Yeah. I just read a bit about distance to rifling and velocity. I just realized I got a lot to learn.... I've been loading 10 years.

 

[VKC]

If everything is consistent and you adjusted for velocity change with temperature, then it is likely your bullet seating length and how far you are from lands. Jammed, highest pressure and speed. Touching lands, high pressure and speed. Off lands, lower pressure and speed.

 

[Aimsmall55]

If everything is consistent and you adjusted for velocity change with temperature, then it is likely your bullet seating length and how far you are from lands. Jammed, highest pressure and speed. Touching lands, high pressure and speed. Off lands, lower pressure and speed.

I've thought about it and just decided that speed isn't everything. When you shoot groups like this who cares:

 

[turbo54]

That's some nice shooting right there! A testament to the rifle, ammunition and marksman alike.

I've certainly heard plenty about new barrels speeding up over the first 50-100 rounds, but never actually experienced it (that I know of).

I have, however, experienced them slowing down a bit as they age. My 284 gave up ~30-40 fps by about 700 rounds.

 

[Aimsmall55]

That's some nice shooting right there! A testament to the rifle, ammunition and marksman alike.

I've certainly heard plenty about new barrels speeding up over the first 50-100 rounds, but never actually experienced it (that I know of).

I have, however, experienced them slowing down a bit as they age. My 284 gave up ~30-40 fps by about 700 rounds.

Thanks turbo, it's truly an incredible rig. I've got the same rifle in a .308 ... It's VERY accurate , but nowhere near the same ballpark as the 6.5 at distance. Gotta love that 6.5 BC!

 

[Killswitch Engage]

I'm at 1000 rds on my creedmoor with no apparent throat erosion or velocity loss at all. If I had to guess its your chronograph. I didn't see whether you confirmed your dope or not?

 

[Aimsmall55]

I'm at 1000 rds on my creedmoor with no apparent throat erosion or velocity loss at all. If I had to guess its your chronograph. I didn't see whether you confirmed your dope or not?

I have. At 520 yards my dope was .5 to .75 moa more. Don't have it own me. But I have confirmed dope

 

[Dallas4rceMarine]

nice group! what app is that? looks to be pretty handy

 

[Aimsmall55]

nice group! what app is that? looks to be pretty handy

Thanks, it's Ballistic :AE. What you do is take a picture of your group, scale it and bam it calculates your group. It's pretty cool....

 

[Dallas4rceMarine]

much appreciated sir, I look forward to using this in the future!

 

[bohem]

Very nice shooting! My 6.5CM dropped avg 23fps from round 1080 to round 2687 when I re-chrono'd.

I didn't chrono anything for the first thousand or so rounds because I was being lazy, I just went out and shot on paper, tracked the drops and differences and built a JBM simulation that matched it.

Since you have all that 1x fired brass, are you interested in selling some of it? I'd be interested in potentially taking 200-300pcs off your hands.

 

[steve123]

I'm going to guess that part of the reason is you are using a Chrony brand chrono and the other is you are using a electronic scale. I'm done with both.

 

[Aimsmall55]

I'm going to guess that part of the reason is you are using a Chrony brand chrono and the other is you are using a electronic scale. I'm done with both.

No it's a ced mellinium 2. And yes , electronic scales but I double check powder weights with two charge master scales.