She's running a little hot

KDX

KDX

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I took my 17FB out today with the Chrony to see what my loads were shooting at. I put about 10 rounds through it with the lowest at 4290FPS up to 4435fps. They seemed to speed up a bit as the barrel warmed up. This is with 19.9gr of Benchmark. The OAL on these loads is 1.830"-1.833" and the brass is brand new that has only been neck sized and chamfered. Winchester small rifle primers were used. Hodgdon's website lists the max at 20.0C for this powder, but the speed quite a bit lower. There's a pic of some primers that look like they might be beginning to crater. Ideas or suggestions would be appreciated. As far as it appearing that I'm shooting down the road, it just looks that way due to the angle I took the pic from. I was shooting downward into the ditch and there are no farms for miles.

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Nice speed, should blow gophers up real good!!!! R:d:

Primers look fine.

It's a Rem action (thats my guess by looking at those primers), they have a generous firing pin hole so I wouldn't judge by the cratering.

Your primers are still nicely rounded on the edges.
 
How was the bolt lift? stiff or easy. use your calibers to guage brass dimensions against book specs.as said above the primers appear to still have a nice round edge.
 
The bolt lift is a little stiff, but no more so than when the chamber is empty. The rifle has a 'tight' bolt.
 
It would help to know what grain bullet you are using as even with a 40 grain pill that is pretty fast. I am inclined to believe that your chrony is off. As I recall a 40 grain load should cap out on a 221 FB at around 3300 FPS but I remember I was able to achieve 35-3600 FPS which is smoking fast - that was with magical Lil'gun and 40 grain Nosler BT. Even with a 35 grain pill, I wouldn't think that you could gain another 800 FPS. I would replace the battery and take the sun cover off your chrony as something doesn't seem right. Your load looks alright from the primer but you really can't tell if it is too hot solely by primers - especially considering that you are loading in the winter/spring frame. When summer comes you may have an unpleasant surprise. With high end factory guns you can generally run hotter loads as their tolerances are tighter but it still wouldn't be nice to have a blown apart cooper as I doubt they would honor a warranty on a handload.

Nevermind I just read that it is a 17 FB.... Grr I hate misreading... If you are shooting 20 grain or 25 grain bullets that doesn't seem too far off.
 
I've been loading for a 17 Mach IV (the wildcat version of the 17 FB) since 2003 and a 17 Rem since the mid 90's. Your primers look fine other than a small amount of flow back. If that is a concern then switch to a Rem 7 1/2, Rem BR or CCI 450, they have thicker cups and will stop the flow back but based on the pictures it's not extreme in any way. I also found that when I went to one of the three primers listed my groups shrunk.
 
Thanks for all the replys. Any idea why there is so much velocity difference between Hodgdon's stated 4013fps with 20.0gr and my 4435fps with 19.9gr?
 
the bases of the case heads are marked up pretty good , that may indicate high pressure as the head is thrust into the bolt face .

remington brass can also be on the soft side too .

i can see some flattening of the primers , and you do have a bit of a lip around the edge where the firing pin hits the primer , again signs that your starting to get a bit hot .
 
Chuck McCann said:
I've been loading for a 17 Mach IV (the wildcat version of the 17 FB) since 2003 and a 17 Rem since the mid 90's. Your primers look fine other than a small amount of flow back. If that is a concern then switch to a Rem 7 1/2, Rem BR or CCI 450, they have thicker cups and will stop the flow back but based on the pictures it's not extreme in any way. I also found that when I went to one of the three primers listed my groups shrunk.
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There's nothing as entertaining as a wildcat of a wildcat. :D
 
I would guess the speed diff is probly from the alt and temp differances from the listed specs to what your chrony says and nothing saying the chrony aint out 100fps.I would back off a bit by the look of the primers.
 
your speed might be going up as you shoot because of fouling in the barrel. oddly enough the harder it is for the bullet to go down the barrel the faster it will go. (increases pressure so increases speed). the primers look fine on those. bolt guns are generaly quite good at holding up to high pressure.

the speed difference might be the length of barrel. if your barrel is about 4 inches longer it might account for the 400FPS difference.
 
Altitude won't make any difference to muzzle velocity.

With such a wide spread of measured velocities (145fps), I wonder if your Chrony is seeing the bullets erratically? Especially since your photo shows a blue sky - were you using the light diffusers? (I normally don't use them, but I will put them on when I get trouble or funny results - sometimes that fixes things).

Something you can do is to always bring a .22 rifle with you. Fire a shot or three over your Chrony when you set it up, and also when you are finished for the day. Can help answer niggling questions/doubts.
 
Thanks again. I didn't have the diffusers on and the barrel is 22" long. The readings were (in the order they were shot) 4290, 4341, 4359, 4331, 4392, 4435, 4416, 4383, 4411. I think I'm going to back them off a 1/2gr or so and try to find something that is accurate (while watching for signs of pressure) and then check the velocity.

edit to add....I called Cooper and the bolt lift issue was due to being under lubed by me. It's much better now.
 
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KDX said:
Thanks for all the replys. Any idea why there is so much velocity difference between Hodgdon's stated 4013fps with 20.0gr and my 4435fps with 19.9gr?
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Tighter chamber or barrel, different lot of powder. That's why they say to start 5% - 10% below and work up.

I experienced about the same thing with a 300 winmag, worked up a load to book max and everything looked ok until i put it over a chrony and found it was 220 fps faster than the Lyman book predicted. Be careful, higher velocity usually indicates higher pressure, everything being equal.

The primer outside edges are still rounded, extraction is unchanged, so it doesn't look like you are approaching catastrophic failure but being 400 fps higher than the reload data is definitiely cause for concern.

It is a good idea to buy a box of factory ammo so you can compare velocity and web expansion with your reloads. If you work up your load from a minimum, you'll be able to compare web expansion with different powder charges and see when it starts to climb past the baseline you measured on the 1f factory load. Comparing the measurement from an unfired case doesn't tell you anything useful.
 
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