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5.56 chrono data


survivalshop

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I had a chance to go over most of the data from my Marathon range session last week & found some interesting things about bullets.

First , the rifle , Pre ban AR 15 & I removed the original matched upper ( bought it as as a matched set from Olympic arms some where in 1979-80 ) put a Tactical Machine flat top upper on , which is a tighter fit than the org. ever was.( & I mean tight fit, the Org. was not loose at all )

Olympic Arms -24 " Ultra match , HB in 5.56 with 1-10 rifling.

Burris 3x9x40 Tac 30 scope (new )

All bullets were taper crimped , with the FMJ's as low on the crimp grove as I possibly could .

All charges were hand weighed , WC 846 powder. two different primers , CCI & Rem. bench rest.

Bullet -55 gr. FMJ made by Armsco ,I think, from Midway ,bulk bullets , (Avg. group @ 100 Yrds 2 1/2 " )

55FMJ, CCI, 23 gr. , 2.238" COL.

Avg. vol. 3043

ES- 217

SD- 95

55 FMJ, CCI , 24 gr. , 2.238" COL

Avg. vol. -3056

ES-66

SD-24

55 FMJ , RBR, 23gr. 2.238" COL.

Avg. vol. -3017

ES- 324

SD- 123

55 FMJ , 23.5 gr. , RBR , 2.238 " COL.

Avg. vol. - 3086

ES- 238

SD- 93

55 FMJ ,24 gr. RBR. 2.238" COL

Avg. vol.-3076

ES- 159

SD- 54

Following are Sierra Match King bullets

52 SMK, 24 gr. , RBR, 2.239 COL.  ( best group ,under 1/2 "@ 100 yrds )

Avg. vol. - 3122

ES- 134

SD- 47

55 SMK, 24 gr. , RBR , 2.262 " COL (? ) (about MOA )

ES- 70

SD- 23

69 SMK, 23 gr., RBR 2.245" COL. ( second best group , almost as good as the 52 gr. SNK 's )

ES- 27

SD- 9

So you can see the bullet makes the difference , of course price is up there on any match bullet . I think the un-uniformity of the non match bullets is what got the ES spread up on most of the 55FMJ's . Not sure on the 55 gr. SMK's , the bbl. may just not like 55gr. bullets of any sort or I have to do some tweaking of the charge & or COL.

I have some Hornady 55gr. FMJ's to try yet & I've been told they will work much better, we will see.

I am loading this rifle up for Predator hunting in Ohio , when I go up there for gun season , so I will not be using match bullets ,but am thinking of going to Barns bullets of some sort .

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I am loading this rifle up for Predator hunting in Ohio , when I go up there for gun season , so I will not be using match bullets ,but am thinking of going to Barns bullets of some sort .

Hogs, by chance?  Try out some 70gr TSX bullets.  <thumbsup>

post-71-136297278098_thumb.jpg

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Wow I'm really surprised by the es & sd numbers from the Armsco bullets the 55 FMJ, CCI , 24 gr. , 2.238" COL looked the best on the numbers. Are you going to try to develop that load to see if you can get tighter groups or is about the best its going to do from your rifle?

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I just loaded some Hornady 55 FMJ's & a bunch of the 52 gr. SMK's .

The 55 FMJ's I added 0.4 gr's. , to 24.4 gr's of powder & shortened the COL to 2.225 "( just a test , I like to keep COL as long as possible , for mag feed & this is going the wrong way ,but still in the crimp grove ) , why I went that way is just a hunch , but I should have no problem with the 55's in this 1-10 twist bbl. ,but ya never know.., it is 24 " long & 1-10.

It was the first time I chrono'ed a 5.56/.223 & the SMK 's didn't give me any surprises , even @ almost twenty years young . The 55 FMJ's did surprise me though , they were on the most part , all over the place velocity wise. & one thing I'm glad of & also surprised me , is the Vol. of a developed round with out the use of a Chrono .

98

I believe the 70 gr. is not recommended for my twist rate , but since its dogs I'm going to hunt ( no not the type you take home to momma ) , there 53 gr. TSX or TTSX is what I'm going to try out first .

I also may give some of the ammo to a guy's son at work for his first deer hunt & he's using a single shot .223 , with 1-12 twist ,for it. 

My shots , if any , will be under 200 yrds..

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Tried the Honady's out & I need a real trigger in this old war horse , this std trigger is $hit .

I gave the barrel a good cleaning with Hoppes copper solvent this weekend & it took for ever to get the patch clean . I didn't realize the bbl. had so much copper fouling .

I went to the range today to test fire a customers rifle & took some of the new hand loads for this 5.56 & a funny thing happened , for a rifle that was some what sighted in, at least an inch out of the bull , the rifle shot  5 1/2 " to the left . No dropping of the rifle or changing anything , except a good cleaning.

I think that copper fouling was doing things to this barrel & yes , this was the first time I used the Hoppes copper solvent on this barrel & glad I did , because after adj. the scope , rifle was very consistent , but my trigger is not .

The 52 gr. SMK's still shined ,but the Hornady 55 gr. FMJ's shot a lot better than the Armsco bullets & I will be going back to my org. COL..

No Chrono today , it was 97 degree's out there & I was all by my self at the range.

I'm not going to shoot this rifle till I get a real trigger in her .

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