The new AR.....

[62chevy]

In an interesting note even the 36 cal 1858 Rem cap & ball dinged the plate making visible/feelable dents from 25 yd ....... 159 yrs and still a lot of authority.

20150906_140339.jpg

Weld 'em shut and try again, should be fun. LOL just kidding RBHarter.

[RBHarter]

I have some 1/2 inch but I'm beginning to question that already . I've poked holes in stuff and even knocked chunks off chanel steel but this is a first to punch solid steel . I think the holes are about 30-31 in the plate .

[RBHarter]

I got out this morning for some much needed recoil therapy.

Somewhat mixed results
By the end there was enough data to determine a cause.
1 brass FC, 1 primer CCI SRP, 3 powders, 1 bullet NOE 279-124 RNFP.

10x
21.0. error 2 no readings
21.5. 2048. 2020. 1958
22.0. 2060. 2082. 2088
22.5. 2104. 2057. 2086
3-4 eye inches

H4198
20.0. 1905 1937. 1932
20.5. 1951. 1995. 1983
21.0. 2009. 2026. 1990 these 5 3". Plus 2 @20.5

H322
23.0. 1959 2045. 2050. 2 touching
23.5. 1973. 2090. 2095 2 under an inch
24.0. 2077. 2103. 2049

There are 2 possibilities for having such a wide swing in this set and the last,
A. I have another very touchy case sensitive rifle or,
B. The SRP is that different from the #41.

All the brass would have ejected into a 15 gal wash tub with 20 of the 30 in a 5gallon bucket.
10x has a book Max of 25.5 with a Speer 130 SP. It showed some flattening of the primer but they still have round shoulders.
Hogdon only lists data for 4198 and 322 up to 115 gr bullets so these 2 are no man's land for data here. 4198 is slow/low pressure enough to be able to sneak up on it. There is a link above to a spread sheet from a reloading program that gave me a guide to go by, thanks to RD. It also is held to 42kpsi for the SAMMI chamber. These showed no hint of high pressures ejecting at 2:00 and locking open on the empty mag. Where the velocity is close the hits were very close but the low or high went wide. All 30 rounds did manage to stay inside 9" at 100 m.
I moved out to 110 yd in hopes of saving the plate some I was mistaken..... I wish I had the fortitude or financial well being to check the impact speeds.........

These 30 will get decapped, annealed, 80% sized and weigh lotted. Then the lots will move on up with 4198 and 322.

[akuser47]

Good info, though the results aren't in your wanted range yet. Another option you can test is to use these as fire formed only neck size and see if they provide a more consistent group. Function can be touchy in some with fire formed. Who knows I look forward to your findings

[RBHarter]

Funny thing happened when I started weighing cases ........
They were heavy and light and really light, I have a set of matching brass now so I'll run the necks and whatever the die hits of the shoulder OD . With this bullet there is a lot of case space left as the base is at the bottom of the neck I may break down and try a compressed load of 4350 like they did with the 4831 surplus in the 06' clan in the 60s and 70s.

[RBHarter]

Ive found some other things to tinker with.

2015-09-19 19.03.43.jpg

A member elsewhere wants to shoot some subsonic loads in a 1-11 twist which limits weight or more practically bullet length.
So for practical demonstration I thought some examples for direct comparison.

RCBS 7mm-168 , 1.154 inside the case .597 to feed and chamber .
SST 120 1.123 inside .532
NOE 279-124 .908. Inside .310
RCBS 27-130 .948 inside. 502
The last 3 are subject to magazine length .

In my tinkering I found that the case with with a NOE Bullet will accommodate 29 gr of IMR 4350 , that is considerably more than the 25.1 gr at 105% of the loading program . By straight math it comes out at 126% . No complaints here I greatly appreciate having the numbers . Nope not going there straight out , but there is room with the low pressures to move up to fill the the case .

I'm thinking that the 168 might be too long I do have a 150 that will be shorter but much lower BC.

[Maximumbob54]

My guess is "RCBS 27-130 .948 inside. 502" will choose the best accuracy. But it's just a guess.

[RBHarter]

It's a great bullet , I just can't get it where needs to be to be legal out here for big game. It really shines in a paper patch in the 7x6.8 and will make the cut with good groups . I'm beginning to think maybe this AR is just a 3" rifle...... it is what it is and I can live with that .

[RBHarter]

I've done some more tinkering with the rifle and dropped back to a known load . It appears that 1 of the top stepping loads (I got into the 2300s) failed at the gas port. It's not a big surprise that failure however derailed all efforts, apparently a gap between the crown and flash hider 30 cal shoulder trapped otherwise harmless fouling making a rather ugly crown and poor release.

I changed the hand guard from the A2/A3/M4 to a free float with rails and a low profile gas block . This was where I found the fouled crown . So with the bird cage left off I shot loads known to ,well at break in ,shoot a given group . The loads actually shot smaller groups by a fair margin . The original 1st 10 round 3" groups have closed to under 2" so bagged they could be as small 1.5 maybe even less with a more familiar shooter .

I currently have just $475 in this rifle which in terms of ARs is pretty inexpensive and I've learned volumes about the load tolerance.

[DaveInGA]

RB,

How you doing on this rifle, any updates?