Maximizing magazine COAL in FN SPR and loading

[QuietShootr]

In doing some load development for my FN SPR A3G, I found one using my bullet of choice (175SMK)that shoots unbelievably well (sub .3) and gives me the velocity I want. Trouble is, it's WAY too long for the magazine. My rifle measures 2.890 to the lands from the ogive of a 175SMK, and the bug-hole load is 2.893 COAL (2.880 to the ogive), which is WAY too long to feed.

It appears that the mag will allow 2.812 or so to feed but that's about it. Is it possible to mill or lengthen the magazine well to allow longer seating depths? Shorter loads shoot pretty dramatically worse.

Anyone have any suggestions, or am I stuck with a single-shot rifle?

 

[Tengo1]

Re: Maximizing magazine COAL in FN SPR and loading

Your only stuck if you decide that's the only bullet and load you want to use. Factory loaded Federal 175 Gold Medal Match and Southwest 175's shoot like a dream in my A3G. 155's shoot great to, and 168's shoot the best. I wouldn't get hung up on one load, especially if you have to modify the mag well (which will instantly void your warranty). Keep tinkering with rounds until you find one that can do what that load does but fit the mag. For what it's worth, in my A3G Hornady 168 grain Amax's are more accurate and consistent at 1,000 yards than 175 SMK's.

 

[greyson]

Re: Maximizing magazine COAL in FN SPR and loading

Agree on something here. What you see at 100 isn't guaranteed at 1000. I would recommend confirming out to range. I have followed your posts somewhat since I also run the same rifle. For a while it seems you had to have 1/4 MOA out of your loads or you were dumping the SPR. That 1/4 isn't guaranteed out to 1000.

So does this mean you are not selling your rifle now?

Regards,
Greyson

 

[JBomb]

Re: Maximizing magazine COAL in FN SPR and loading

I'm not really sure if it would work but maybe try to modify the wsm internal mag and floorplate. Again, I'm not sure if it would work, but my SPR wsm internal box mag measures about 3.030. I load my ammo to 2.995 COAL. If you need measurements let me know.

Kind regards,
Jared

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

I have an idea. I noticed the mag box has a spacer in the back that takes up about 2x what I'd need to get 2.900 loads in there. Why couldn't I just remove the spacer, or replace it with a somewhat thinner one?

And Greyson, no, I was talked out of it for the moment. If I can figure out a way to get this 2.885 bug-hole load in a magazine, you bet I'm keeping it.

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JBomb</div><div class="ubbcode-body">I'm not really sure if it would work but maybe try to modify the wsm internal mag and floorplate. Again, I'm not sure if it would work, but my SPR wsm internal box mag measures about 3.030. I load my ammo to 2.995 COAL. If you need measurements let me know.

Kind regards,
Jared </div></div>

That would be great. Maybe a pic of the internal box, and the presence or absence of a spacer in the rear of the box? I have mine apart and I can take a pic of that. But it sure looks like it wouldn't be that hard to pop a weld, take that spacer out, and replace it with one 1/2 the length.

 

[19Scout77]

Re: Maximizing magazine COAL in FN SPR and loading

CDI Bottom metal. AI mags with front spacer removed....2.900"+ mag capacity. Problem solved.

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 19Scout77</div><div class="ubbcode-body">CDI Bottom metal. AI mags with front spacer removed....2.900"+ mag capacity. Problem solved. </div></div>

SO fucking done. How hard is it to take out the spacer?

 

[greyson]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuietShootr</div><div class="ubbcode-body">

And Greyson, no, I was talked out of it for the moment. If I can figure out a way to get this 2.885 bug-hole load in a magazine, you bet I'm keeping it.

</div></div>

OK. I watch your posts with great interest. BTW...I can't imagine wanting to sell my A3g. It rocks.

Regards,
Greyson

 

[19Scout77]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuietShootr</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 19Scout77</div><div class="ubbcode-body">CDI Bottom metal. AI mags with front spacer removed....2.900"+ mag capacity. Problem solved. </div></div>

SO fucking done. How hard is it to take out the spacer? </div></div>

Drill out the two spot welds and its done...but you REALLY need to tig/mig the holes closed to avoid having a problem with the bullet tips hanging up. Another option is to buy the Alpha mag that is already set-up without the spacer. By the time you are done, you are going to drop $270 or so (including one mag), plus smithing costs to have it done, but you will now have a 10 rd drop mag and the space you need.

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

Oh, wow. Do you know if the FN action will require extra relief of the feed ramp to use the Alpha Type 2 magazines?

 

[19Scout77]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuietShootr</div><div class="ubbcode-body">Oh, wow. Do you know if the FN action will require extra relief of the feed ramp to use the Alpha Type 2 magazines? </div></div>

You must do a minor amount of machining to the action to permit the use of AI type mags. No big deal.

 

[turbo54]

Re: Maximizing magazine COAL in FN SPR and loading

When I measured my current SPR action, looked like my feedramp needed notching to clear the bullet tip at COAL > 2.900"

FYI: CDI has a special until tomorrow, DBM bottom metal for $169. Inletting is $60. Not sure how much to relieve the receiver, which only the FN requires.

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

I just sent the rifle off to CDI - hopefully he can get it squared away with the Alpha Type 2 magazine. That sounds exactly like what I need.

 

[turbo54]

Re: Maximizing magazine COAL in FN SPR and loading

Glad it's gonna work out for ya!

 

[19Scout77]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuietShootr</div><div class="ubbcode-body">I just sent the rifle off to CDI - hopefully he can get it squared away with the Alpha Type 2 magazine. That sounds exactly like what I need. </div></div>

Good move. Jeff is ACES! You will be happy with the change.

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 19Scout77</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: QuietShootr</div><div class="ubbcode-body">I just sent the rifle off to CDI - hopefully he can get it squared away with the Alpha Type 2 magazine. That sounds exactly like what I need. </div></div>

Good move. Jeff is ACES! You will be happy with the change. </div></div>

Excellent!! this is going to be a seriously nice stick if all this works right.

 

[19Scout77]

Re: Maximizing magazine COAL in FN SPR and loading

I have owned both factory sprs and customs built on spr actions (6 in total) all built with cdi bottom metal and they all worked and looked great.

 

[2Shots]

Re: Maximizing magazine COAL in FN SPR and loading

I sent my SPR to Jeff at CDI also, 3000 rounds on it and it feeds perfect every time, I use the AI mags. You could use the Alpha mags and load longer if you like but I stay with the AI's. I load for reliability at 2.820.

 

[Xtremegunnr]

Re: Maximizing magazine COAL in FN SPR and loading

Getting that extra .080 is not gonna really affect much. You could use a different powder to get the velocities and from what i have tested 2.815 always works just fine.

 

[QuietShootr]

Re: Maximizing magazine COAL in FN SPR and loading

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Xtremegunnr</div><div class="ubbcode-body">Getting that extra .080 is not gonna really affect much. You could use a different powder to get the velocities and from what i have tested 2.815 always works just fine. </div></div>

It isn't the velocity, it's the accuracy. Seating them 0.010 off the lands makes the 5-round groups shrink from 1.00" to 0.30". No amount of dicking with powder is going to give a better result than taking out 0.060" of jump.