Nature Boy, that's a really good setup you have there. I like the FN actions. My gf has a 6.5x47 Lapua built on an FN action and it's a tack driver ... literally a one hole gun at 100 yards. I like the safeties on the FN, Kimber, Winchester and AI rifles that control the firing pin.
FN SPR A3 First Impressions
- Thread starter Nature Boy
- Start date
- Status
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
Thanks MCMXI, anytime you want to trade for one of your AI's give me a shout.
PB,
If you have a Dremel it's pretty easy to cut the slots in the case. That's how I did it using these little cut off wheels
PB,
If you have a Dremel it's pretty easy to cut the slots in the case. That's how I did it using these little cut off wheels
Gtscotty
Member
- Joined
- Jul 2, 2007
- Messages
- 3,635
I really think it would be easier to use something like Hornady's O.A.L Gauge than to cut cases and hope the bullet doesn't move from it's actual oal when you withdraw it from the chamber. I use Hornady's O.A.L Gauge for all my rifles, and I find it to be very simple and effective.
These threads are really re-igniting my SPR lust, I'm seriously considering plunking down on an A1. I don't think I've read a review from an SPR owner that doesn't mention excellent accuracy. I am curious about how the rifles are twisted though. My current .308's have 11 and 10 twist, but from reading a bit, it seems like 12 works fine for the standard 168gr-175gr HPBTs and even 190gr HPBT's.
Are any folks who shoot a 12 twist .308 having bullets of those weights/types lose stability out to say 700 yds? I ask because I see how a 10 twist might be mandatory if you're trying to get out to 1k, but my local range stops at 700 and it seems like standard match bullets and a 12 twist would get you there under most circumstances.
Natureboy,
Very nice setup! Does the SPR's magazine restrict your OAL, or are you able to approach the lands?
These threads are really re-igniting my SPR lust, I'm seriously considering plunking down on an A1. I don't think I've read a review from an SPR owner that doesn't mention excellent accuracy. I am curious about how the rifles are twisted though. My current .308's have 11 and 10 twist, but from reading a bit, it seems like 12 works fine for the standard 168gr-175gr HPBTs and even 190gr HPBT's.
Are any folks who shoot a 12 twist .308 having bullets of those weights/types lose stability out to say 700 yds? I ask because I see how a 10 twist might be mandatory if you're trying to get out to 1k, but my local range stops at 700 and it seems like standard match bullets and a 12 twist would get you there under most circumstances.
Natureboy,
Very nice setup! Does the SPR's magazine restrict your OAL, or are you able to approach the lands?
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
Scotty, it depends on the bullet. The 168 AMAX and 168 SMKs just fit. 168 Bergers do not.
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
I loaded up 100 rounds last night and couldn't help myself. Stopped at the range on the way to work and shot all of them. I think I need an intervention
Gtscotty
Member
- Joined
- Jul 2, 2007
- Messages
- 3,635
It's good to hear that 168gr Amax's and HPBT's work with the SPR DBM. I wonder how the same style 178's do? It looks like the A1 is offered with a floor plate or DBM, just trying to see if there is any down side to the DBM.
I'm still curious if anyone has actually had problems with a 12 twist .308 stabilizing normal weight projectiles, or if it's mostly a theoretical problem.
Gotta say, I'm jealous, I wish I could start my work days that way...
I'm still curious if anyone has actually had problems with a 12 twist .308 stabilizing normal weight projectiles, or if it's mostly a theoretical problem.
Gotta say, I'm jealous, I wish I could start my work days that way...
The Miller Bullet Stability Calculator shows that a Hornady 178gr A-MAX with a length of 1.318" is on the bubble at the muzzle with a 1:12 twist and a MV of 2,600 fps. Ideally the SG should be over 1.4 to be gyroscopically stable.
1:12 twist, 178gr @ 2,600 fps
SG = 1.46
SG (vel. corr) = 1.42
SG (atm. corr, 50F, 28.5 in.Hg) = 1.47
1:10 twist, 178gr A-MAX @ 2,600 fps
SG = 2.10
SG (vel. corr) = 2.05
SG (atm. corr, 50F, 28.5 in.Hg) = 2.11
The bottom line is that you won't have stability issues with 150gr, 155gr, 165gr or 168gr bullets with a 1:12 twist at typical muzzle velocities. 168gr SMK bullets (L=1.215") are in the 1.7 range at the muzzle with a 1:12 twist and MV = 2,600 fps.
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
Scotty, I'm loading some 178 AMAXs to the lands next so I'll let you know if they fit. And I think either DMB or floorplate is more preference than any practical concern. With the DMB, I leave the mag in, set the round on top and let the bolt chamber it in normal operating fashion.
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
MCMXI, what does your calculator say about 180g Nosler BTs in a 1:12? The reason I ask is you can see how the shoot on page 1 of this thread. As the picture shows, I can cover 5 shots with a dime and my MV was in the 2550 range
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
The length is 1.360 nominal.
(I won't tell it that it's not supposed to be stable
)
(I won't tell it that it's not supposed to be stable
)Nature Boy,
Here are the results for a 180gr Nosler BT @ 2,550 fps. It's a bit below 1.40 but your results indicate that the SG value can be less than 1.40 and the bullet still shoot well. It would be interesting to see how much below 1.40 you have to go before problems show up.
Here are the results for a 180gr Nosler BT @ 2,550 fps. It's a bit below 1.40 but your results indicate that the SG value can be less than 1.40 and the bullet still shoot well. It would be interesting to see how much below 1.40 you have to go before problems show up.
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
I just did the one scotty references above (JBM) and it asks for the ballistic tip length. That seems to make the difference. Without it I get the same 1.3 SG you do. When I add the tip it brings it up to over 1.6 SG. That may be the missing variable
Flatbush Harry
Member
It's not a FNH SPR but rather a FNH (SC) Win M70 in .30-06. That said, a 5-shot 100 yard group:
[/URL]
Win 70 actions by FNH are good shooters.
Harry
[/URL]Win 70 actions by FNH are good shooters.
Harry
dubbleA
Member
With all this talk about FN's SPR I guess I'll knock the dust off of mine and shoot it on my next trip to the ranch. Haven't fired it in several years, I'll have to find its log book and load a few rounds up.
Mine wears a 8.5x25x50 Leupold Mark IV in Badger rings atop a Near 20 moa base.
Mine wears a 8.5x25x50 Leupold Mark IV in Badger rings atop a Near 20 moa base.
USSR
Member
My 1st Gen. FN SPR loves to launch 190SMK's to 2700fps. No stability problem with it's 1-12" twist.
Don
Don
P.B.Walsh
Member
That is very impressive, I would have thought 190 grain projectiles would have been out of reach for the 1-12" twist. Do you know the length of the bullet?
It seems the myth of "you need a 1-10" for anything above 168 grains might could be challenged.
My 155 TMKs are about 1.275" in length. Just to note.
It seems the myth of "you need a 1-10" for anything above 168 grains might could be challenged.
My 155 TMKs are about 1.275" in length. Just to note.
USSR
Member
I just measured one with my calipers, and I get 1.364". I believe I load to an OAL of 2.840". I believe the velocity I am able to achieve helps a lot.
Don
Don
OP
OP
Nature Boy
Member
- Joined
- Apr 21, 2015
- Messages
- 8,261
Getting 5 shots touching at 200 has been elusive, but I'm getting close
P.B.Walsh
Member
Dang I wish I could do that at 100 yards. I have much practice to undergo!
- Status