Loading for AR, primer question

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Loading for AR, primer question

Postby Kiss of Death » Sun Feb 09, 2020 6:04 pm

The published load data for the 450 Bushmaster (from Hodgdon) uses Winchester small rifle primers. Would it be correct/advisable to switch to a CCI 41 for use in an AR-15? How much noticeable impact would this change have on the load (is it enough to require that I should start lower)?

(loading Barnes 275 TSX with Hodgdon H110)
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Re: Loading for AR, primer question

Postby Al in Mi » Mon Feb 17, 2020 6:53 am

Don't know where that #41 stacks up for "hotness", have heard/read the cup was a bit thicker or harder, but all I use anymore is the CCI 450 which has worked flawless in any loads I've tried over the years.
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Re: Loading for AR, primer question

Postby plant_one » Mon Feb 17, 2020 2:01 pm

anytime you change a component, you need to do at least a partial workup to make sure nothing changes for bad.

i believe the rule of thumb is back up 10% and work back up from there for basic testing on any unproven load in your firearm.

at the very least i'd want to back down 5-7 steps at 0.5gr intervals from your current load and reshoot the top part of the ladder to check for velocity and pressure changes
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Re: Loading for AR, primer question

Postby Hoot » Tue Feb 18, 2020 11:47 am

plant_one wrote:anytime you change a component, you need to do at least a partial workup to make sure nothing changes for bad.

i believe the rule of thumb is back up 10% and work back up from there for basic testing on any unproven load in your firearm.

at the very least i'd want to back down 5-7 steps at 0.5gr intervals from your current load and reshoot the top part of the ladder to check for velocity and pressure changes


+1

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Re: Loading for AR, primer question

Postby Kiss of Death » Sun Mar 01, 2020 9:46 pm

plant_one wrote:anytime you change a component, you need to do at least a partial workup to make sure nothing changes for bad.

i believe the rule of thumb is back up 10% and work back up from there for basic testing on any unproven load in your firearm.

at the very least i'd want to back down 5-7 steps at 0.5gr intervals from your current load and reshoot the top part of the ladder to check for velocity and pressure changes



Will do, thanks for the feedback.

As to the need for a hardened/military primer- is this the better choice to make in this case (AR)?
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Re: Loading for AR, primer question

Postby Al in Mi » Mon Mar 02, 2020 5:44 am

I use the CCI 450, Remmys 7 1/2 is also good.
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Re: Loading for AR, primer question

Postby Hoot » Mon Mar 02, 2020 9:00 am

I've used rem 7 1/2, WSR and Federal 205M, none of which are marketed specifically for being "hardened". Never had a slam-fire in over 2500) 450b loads in my AR platform. Recently, I purchased some CCI 450's to try but haven't gotten around to A/B'ing them against my favorite, the Rem 7 1/2. to see if there is any performance differences, either velocity or their impact upon accuracy.

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Re: Loading for AR, primer question

Postby 303hunter » Tue Mar 03, 2020 8:25 am

I also use CCI 450 in all .my 450 loads. Easier to find for me than Remington 7 1/2's.
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Re: Loading for AR, primer question

Postby plant_one » Tue Mar 03, 2020 1:42 pm

ive been using cci 400's in my ar's since i started reloading - several bricks of them to date. thats their standard cup small rifle (non magnum) primer. when i first started using it i did a bolt slam test (live round, gun pointed downrange at the berm) and while i got small dimpling, even after repeated full bolt drops - i gave up after around 10 attempts when nothing went bang. its been a long while since i tested it so i forget the actual count.. but it was somewhere about 10 attempts. i was also checking bullet movement - both setback or moving out - at the same time.

im sure there's a point where the cci 400 small rifle primer will slam fire, but i dont make a habit of chambering a round more than 4 or 5 times anyway (think hunting, where i'm loading/unloading a couple times a day during deer season) before i cycle it out and turn that round into a practice round anyway.

i think in this caliber - you're going to be more likely to get (excessive) bullet movement from repeated chambering than you will a slam fire with cci 400's.


i do use the rem 7½'s these days for my 450 loads, but thats because i have a bunch of them. i'm still using cci 400's in my 223 and 300 blackout loads since i have several bricks of them to burn thru and lots of load data with them from testing since 2011 when i first started using them as my initial reloading testing primer.

now... if you want to verify my results i would strongly encourage it - just take yourself to the range, point your gun in a safe direction and do a full bolt drop cycle. take your calipers to watch for bullet movement so you dont get into a dangerous thing there, and watch the primer hits as well as OAL changes. you might be surprised what you learn :)

HTH
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Re: Loading for AR, primer question

Postby plant_one » Tue Mar 03, 2020 1:44 pm

Hoot wrote: Recently, I purchased some CCI 450's to try but haven't gotten around to A/B'ing them against my favorite, the Rem 7 1/2. to see if there is any performance differences, either velocity or their impact upon accuracy.

Hoot


i did some testing with two uppers (both bushmaster 20") when we were load testing my buddy's upper. we had both 7½'s and 450's loaded with 38 grains of LG under both the 225 and 250 ftx.
velocity numbers were quite close, and no significant change in accuracy or point of impact with either. for our purposes we consider them essentially interchangeable. i look forward to your results too since i know you've got a much larger testing group of uppers to play with :)
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