Ground squirrel caliber thoughts, 308 bolt/ AI mag

[Kiba]

While I was sitting at my computer Sunday morning I had a bad idea... why not have a varmint barrel spun up for my new AIAE?

I already have a .223 R700 and 24" barrel AR that I currently use for long range squirrel blasting. Both guns are launching 53gr Vmax (.290 BC) at 3250 fps and do a fine job but I'm thinking I want to do a barrel for the AE with a little more power.

Whatever caliber I choose would have to be compatible with 308 case head dimensions and feed out of AICS magazines.

So far I've considered the following:

.220 swift
.22-250
.243
6mm Creedmoor

.22-250 is a known that I've had experience with. I already have .22-250 dies as I use them for reloading a friend's squirrel gun. We launch the 53gr Vmax out of his rifle at 3800fps; a good flat shooter and it really explodes the squirrels. Barrel life is an unknown; he's sitting at about 900 rounds after this season and it's still shooting great.

.220 swift would be similar to the .22-250, I'd probably stick with the 53gr Vmax I already have. I'd lean towards the .22-250 instead as I already have the dies.

For the .243 or 6mm Creedmoor I was thinking of using 58, 65, or 75gr Vmax. Unfortunately the 58gr (at .250BC) and 65gr 6mm Vmax (at .280BC) both have poorer BCs than my current .224 53 max at .290BC. Only when you get to the 75gr Vmax at .330BC does the bullet selection surpass my current .290 BC 53gr Vmax load. Looking at load data for .243 it looks like I could launch a 58gr Vmax at about 3800fps, a 65gr Vmax at about 3650, or a 75gr Vmax at about 3400fps, all of which should do a number on the squirrels and do so quite a ways out. I can't find much in the way of load data for the 6mm Creedmoor but I think it could achieve similar velocites compared to the .243.

Thoughts or suggestions would be appreciated...

 

[turbo54]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

While the 220 is the king of the 22s, its semi-rimmed design is strange, and out of date. It really doesn't do much more than what a 22-250 can.

So....22-250 would really be a top choice, though if it were me, I'd want to do a 22-250AI. What's another $50 for dies?

 

[Kiba]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

Any compelling reason for the .22-250AI over the regular variant? Any significant increases in case capacity or velocity or does the change in shoulder angle possibly help throat longevity of the barrel?

If it's just for reasons of trimming I already have a cutter head and case holder for my Giraud so trimming is quick and painless.

I'm totally open to any and all suggestions. I'm not opposed to a new caliber but a benefit of sticking with .22 caliber is I already have a healthy stockpile of 53gr Vmax.

 

[turbo54]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

Not really. AI cartridges look sexier, and the 22-250 version gives ~100-150 fps extra, but 3800 really oughtta do it just fine.

Don't count on better barrel life. In fact it'll most likely be worse.

 

[Kiba]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

I hear you on the .22-250AI but I don't see a real benefit for shooting Vmax bullets. The best BC of all the .22 Vmax bullets is the 53gr at .290 and I don't see where the added case capacity of the .22-250AI would gain much over the ~3800fps you can already achieve with a standard .22-250 case. If I wanted to shoot say heavier .22 bullets like the 75gr Amax in the 3500-3600fps range then I could see the added capacity of the AI being beneficial over the parent case but for the light 53gr Vmax it just seems like the added case capacity of the AI would require more powder to reach the same 3800fps velocity I can achieve with the regular case.

The 75gr Amax in a .22-250AI would be an interesting choice; if I could drive that to about 3500-3600fps the .435BC is quite good. Considering ballistics only it's a very good combo but I'm not sure how explosive the Amax would be on squirrels-- but my guess it that it will still do a great job.

I just ran comparison ballistics charts. The numbers are drop in inches followed by velocity and energy at 500Y.

.22-250 53gr Vmax @ 3800: -24" / 2180 fps / 560 ft/lb
6mm 58gr Vmax @ 3800: -27" / 1932 fps / 481 ft/lb
6mm 65gr Vmax @ 3650: -28" / 1994 fps / 575 ft/lb
6mm 75gr Vmax @ 3400: -30" / 2054 fps / 703 ft/lb

The .22-250 is the flattest shooter and the 6mm variants are all very close to each other within 500Y with those Vmax bullets. For 6mm I'd probably lean towards the heavier and slower 75gr Vmax just for reasons of retained energy and the higher .330 BC bucking the wind better. For reasons of "fun" I know that the smaller/faster .22-250 would have more of an interactive and explosive effect than the larger & slower 6mm round on squirrels-- but I'm wondering how barrel life between the two calibers would compare...

 

[BuzzBoss915]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

Okay, I'm not an expert on these things, but I have owned two 220 Swifts, a 22-250, two 22-250Ackleys, a 243, a 6mmRem and a 243Ackley and a couple 25'06AIs.

For your purpose, I would get the 22-250Ackley. It has higher velocities than the 220Swift, does not require neck trimming and as mentioned, is a very sexy round.

If you do it, forget about 53 grain bullets because you will be disappointed in the net gain over the standard 22-250. But, if you use 62/65 grain Bergers, that is where the advantage lies. I am pushing 65 grain bullets @ 3925 with 44.0 grains of H414. You will never beat that with a Swift.

And, my 22-243Middlested (with 4 more grains of powder) will only do 3810fps with the 62 Berger. So, the 22-250Ackley is a very efficient cartridge, very hard to beat when you consider case life. I own a Swift and can attest to the tedium of neck trimming to length. With the 22-250Ackley, I have never trimmed a single case, due to the 40 degree shoulder.

There are no flies on the 243Ackley, but for your purpose, I think you would be better served with the 22-250AI. You will never regret it. BB

 

[varmint slayer]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

I vote for just a plain 22-250. No case forming or anything special, just buy cases, load and shoot. Really not worth the extra hassle if you ask me.

 

[Kiba]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BuzzBoss915</div><div class="ubbcode-body">But, if you use 62/65 grain Bergers, that is where the advantage lies. I am pushing 65 grain bullets @ 3925 with 44.0 grains of H414. You will never beat that with a Swift.</div></div>

3925fps for a .224 64 gr Berger varmint bullet is flying. What twist is your barrel?

The 64gr Berger varmint bullet is .294BC while the 53gr Vmax is .290BC. I know I can drive a 53gr Vmax to 3800fps in a standard .22-250 without pressure issues. The Berger has the better BC and higher initial velocity, so looking at the numbers at 500Y:

53gr Vmax @ 3800: -24" / 2180 fps / 560 ft/lb
64gr Berger Varmint @ 3925: -21.5" / 2284 fps / 741.6 ft/lb

The Berger is clearly the winner for performance. However, they're about $31 a box where the Vmax are only $17 a box. I suppose I need to decide if the performance gain is worth the extra bullet cost. I typically burn about 1200 rounds a year out of my ground squirrel guns so the cost difference is only ~$170 plus the added effort of fireforming the AI brass.

I'm paralyzing myself with data again. I need to get a barrel ordered soon if I want it in hand by the end of March...

 

[BuzzBoss915]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

Well, first of all, my data was originally with the 65 Berger. The die broke and as I understand, the replacement came up 64 grains. I have some of both as well as a special run of the Starke 65 grain. That data is in a 12 turn 28.5" Hart barrel. The Middlested data is with the discontinued 62 Berger which I bought at closeout price of $15, proving very accurate and very deadly on coyotes.

I also have a 223Ackley on a 700VSSF which I use on squirrels with a 55 VMax, if you are concerned about cost. I don't remember how much, exactly but I buy them in the 250ct. box. A coyote gun needs a little more authority, like those mentioned above, but for moderate range prairie dogs, the 223AI is what I use.

The choices are vast, but if you want to know what I use mostly and what sits in the safe; you just can't beat a nice 22-250AI which is why I have two, the other has a very normal 26" barrel. I wouldn't make the mistake of getting a fast twist, as long as you can drive a bullet above 190,000RPM, it will stabilize in a 12 twist and last much longer. BB

 

[Kiba]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

Can't do a .223AI as the AE has a 308 bolt face only. I do hope that sometime in the future AI will do a run of AE's with a .223 boltface (as they did back for the limited AW-Varminter run back around 1999-2000.)

The .22-250AI launching either the 64gr Berger Varmint or the 75gr Amax is looking very appealing for ground squirrel shots beyond .223 range and also for coyotes where the extra energy of over my current .223 53gr Vmax load would be nice.

I'm not looking forward to fire forming .22-250AI brass(never done it before) although pistol powder + cream of wheat looks like a good way to go.

I'm still kicking around the idea of a 6mm Creedmoor launching some of the lighter bullets...

 

[DAVETOOLEY]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kiba</div><div class="ubbcode-body">I hear you on the .22-250AI but I don't see a real benefit for shooting Vmax bullets. The best BC of all the .22 Vmax bullets is the 53gr at .290 and I don't see where the added case capacity of the .22-250AI would gain much over the ~3800fps you can already achieve with a standard .22-250 case. If I wanted to shoot say heavier .22 bullets like the 75gr Amax in the 3500-3600fps range then I could see the added capacity of the AI being beneficial over the parent case but for the light 53gr Vmax it just seems like the added case capacity of the AI would require more powder to reach the same 3800fps velocity I can achieve with the regular case.

The 75gr Amax in a .22-250AI would be an interesting choice; if I could drive that to about 3500-3600fps the .435BC is quite good. Considering ballistics only it's a very good combo but I'm not sure how explosive the Amax would be on squirrels-- but my guess it that it will still do a great job.

I just ran comparison ballistics charts. The numbers are drop in inches followed by velocity and energy at 500Y.

.22-250 53gr Vmax @ 3800: -24" / 2180 fps / 560 ft/lb
6mm 58gr Vmax @ 3800: -27" / 1932 fps / 481 ft/lb
6mm 65gr Vmax @ 3650: -28" / 1994 fps / 575 ft/lb
6mm 75gr Vmax @ 3400: -30" / 2054 fps / 703 ft/lb

The .22-250 is the flattest shooter and the 6mm variants are all very close to each other within 500Y with those Vmax bullets. For 6mm I'd probably lean towards the heavier and slower 75gr Vmax just for reasons of retained energy and the higher .330 BC bucking the wind better. For reasons of "fun" I know that the smaller/faster .22-250 would have more of an interactive and explosive effect than the larger & slower 6mm round on squirrels-- but I'm wondering how barrel life between the two calibers would compare...


</div></div>

What about wind drift? The up and down is the easy part.

 

[BuzzBoss915]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

That's a valid consideration. But, speed is a solution for wind drift, or rather, one solution.

As far as the drudgery of fireforming. Have your gunsmith chamber a junk barrel using the same reamer and load any surplus bullets. I have fireformed 100 cases in less than an hour. Have him modify a Wilson seater with the same reamer as your chamber. A very smart solution. BB

 

[30SMK]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

I would say go with a regular old 22-250. You can pick up factory loaded ammo if you are in dire need and it will give you a little more barrel life over the AI variant. But any of the stuff listed will kill pretty well for blowing up dogs or chucks.

 

[Tier 1 Dogwalker]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Whatever caliber I choose would have to be compatible with 308 case head dimensions and feed out of AICS magazines.</div></div>

If you want something different that still has low 22 caliber bullet costs and that is inherently accurate maybe try a 22BR.

It is a 0.473" case head but I do not know if it will feed from your magazine. I know I've read somewhere (probably 6mmbr.com) that 6mmBR was magazine fed successfully but I cannot find the article right now. Googling turned up some hits but not the article of which I'm thinking. So that requirement is unresolved.

http://www.6mmbr.com/22BR.html

 

[twinky]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

+1 for the 22BR. Mine is on its second barrel, on a 700 Rem. action. I use a benchrest follower, to make it single shot, so can't say if it would feed them from magazine. Current load is a 50 gr. Speer TNT @3824 fps, running 30.2 gr. of Accurate 2015. Pretty efficient and very wicked on prairie dogs.

 

[Sudden Impact]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Varmint Slayer</div><div class="ubbcode-body">I vote for just a plain 22-250. No case forming or anything special, just buy cases, load and shoot. Really not worth the extra hassle if you ask me. </div></div>

+1...Why mess with something that works and is a proven cartridge? My .02 cents worth.

 

[BuzzBoss915]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

A plain vanilla 22-250 is fine but we are talking about a higher level. Besides, the Ackley IS A PROVEN CARTRIDGE. BB

 

[Kiba]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

The 22-250AI pushing a 75gr Amax is looking mighty tempting but I still haven't made up my mind on what to go with.

A 6mm variant launching one of the 85-105 weight bullets has the advantage in the wind, but an 85-105 grain 6mm sure seems like overkill on our little ground squirrels though...

 

[former naval person]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

The AI will give you a little bump in velocity, but a lot better case life. That standard .22-250 stretches quite a bit. In a properly chambered barrel you don't have to do the special sizing and firing techniques. Just fire regular .22-250 loads and you'll have good fitting cases.

 

[MTyotehunter]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

or... do a 6mmInternational(6mm-250), you could shoot light 6mm bullets with a relatively small charge and you would get much better barrel life than 22-250 or 220 swift.

Neaver had one but allways wanted to build one

 

[BuzzBoss915]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

I had one, a 6/250Ackley. I never liked it, efficient case and all that crap, personal opinion. I guess I'm more of a speed freak? Which takes so much of the guesswork out of holdover. BB

 

[300ATT]

Re: Ground squirrel caliber thoughts, 308 bolt/ AI mag

I have 17 rem 204 ruger 223 22-250 but the one that always gets the "standing ovations" from the spotters is the 6mm Cheetah (basically 243 imp). Launches 70gr blitz kings at 3800+ fps. That is my vote as you'll get the most "hang time".

The other thought is a 260 w/ 95 grain VMAX ... That one is impressive also.

Good shooting ...